I read a good analysis of Artemis a while back that essentially calculated the cost per hour of time-on-moon and in that sense it was easy to see that the program was a significant upgrade over Apollo and the costs weren't that bad when calculated per hour. Achieving a 10x improvement over the previous generation usually can't be done without doing something new and different that hasn't been done before, and in-orbit refuelling fits right in. Gemini and Apollo had to work out and develop far more tech to do what they needed to do.
What's also fascinating is that they are going with, in VERY BROAD strokes, the concept that was Von Braun's preferred method to achieve this back in the day too, but it was abandoned in favor of the lunar orbit rendesvouz.
For a critique of the current method, I found the SmarterEveryDay lecture on it gave some good food for thought!
What were Von Braun's reasons for something akin to a Near Rectilinear Halo Orbit? Links anyone?
The SmarterEverDay concerns about the orbit seemed to be that while landing or taking off maneuvers were short & low energy (good), it meant the opportunity only came about every couple days (bad).
SED also stressed that Artemis is relying on crulyonic fuel transfer. SED repeatedly pointed out this is a tech that has never been tested, ever.
The more I've thought about that lecture the less I really agree with most of the things he raised, for the simple reason that Apollo is never, ever going to happen again. It's a lot of argument from increduality (e.g. it's easy to pretend starship launch's are "too many", without addressing that practical reusability has been a thing for years right now).
At it's peak, the Apollo project was funded to the tune of 1.1% total US federal outlays during the time period it ran. That's an enormous amount of money, which failed to produce a remotely sustainable result. You got what you got: moon landings done quick, and then never again.
The modern Apollo project is SLS which...is a big, expensive, absolutely cannot fail rocket (which is really a jobs program for preferred contractor districts, with technology choices decided by politicians not engineers).
Basically the SED lecture spends a lot of time gesturing at Apollo, but never addresses the actual problem which is NASA is funded the way it's funded: of course they know they're going to miss their launch dates, they're not funded to hit them, and they're probably going to wind up redesigning the mission once Starship is flying to orbit and actual performance numbers are realized off-paper. The SLS is the SLS for the same reason: at the time the program started there was no SpaceX, nor Space Shuttle and it was something of a national embarrassment the US didn't have a manned space capability but the Russians still did.
In short, for a lecture which opens talking about people worrying about disagreeing with their superiors, he stays well away from the actual live-wires of the issues.
Yeah Apollo was obviously incredibly impressive but was sort of a technological dead-end. There was no path from that program to a permanent human presence on the moon.
If they can really get Starship and orbital refueling working, it's a step function forward.
I tend to disagree. There was very much a evolutionary path forward.
There were already programs like NERVA in development for an advanced nuclear upper stage. Once you have that, making the Upper Stage refuel-able, makes it basically into a multi-use space tug for cis-lunar.
Then you could evolve Saturn 1B into a reusable Saturn 1C, just like Falcon 9. That gives you a reusable heavy lifter. And it would also safe a gigantic amount of money that was spend on Atlas/Titan/Delta in the next 40 years.
The Apollo capsule was not reusable but continuously evolving a capsule design in that direct was certainty possible. But its not the most important part of the system in terms of cost.
What really need more development is the lander itself. Making a large reusable lander would have been costly but not really out of reach.
You can use an occasional Saturn V for large things like Skylab and special deep space mission.
That was a much better path forward then Space Shuttle and ISS.
Yeah but there's still no precedent at all for re-ignition, stabilization, automatic landing, etc. It took SpaceX like 20 tries to do this using 2010's technology and computer automation, with a much smaller rocket.
No! Not at all! The Moon is harder to land on then Mars!
Aerodynamic drag is amazing. It means fins and parachutes work. It means you can slow yourself down without propellant and with passive systems.
Mars actually kind of sucks too because it has just enough atmosphere to interfere with rocket engine ignition but not enough to be able to land on chutes alone. But any amount of parachute and aerobraking is better then none.
But the Moon is terrible: no atmosphere, so you're under engine power the whole way down. The propellant and mass demands are thus much higher.
Thanks, good explanation. My thought on "no atmosphere" is that it eliminates the need for heat shielding to enter it, but I can see how that's not really an issue compared to all the benefits.
Nobody proposed landing a Saturn V. The Apollo lunar base proposal called for a shelter based on the existing Lunar Module[1], along with an extended CSM and LM Taxi hardware derived from the basic Apollo program.
OK, and then what? You can land the tiny capsule that you took back and forth to the moon and call it a permanent shelter, sure, but you're not going to be able to build any kind of substantial base at a rate of one giant rocket per tiny capsule.
Its hard to calculate because non of the costs are really all that clear. There are not even lander contracts for any mission after Artemis 3. It also depends on how long into to future you think this continue.
And I think what that kind of analysis misses is how many important multi-use technologies are developed. Starship will mostly not be used for moon, but financed with moon money.
> Achieving a 10x improvement over the previous generation usually can't be done without doing something new
It is definitely possible if the fixed cost(e.g. R and D, manufacturing capability, testing infrastructure etc) is majority of the cost and scaling up doesn't increase them linearly. Cost of raw materials like fuel or building material would be negligible for Apollo or SLS in comparison.
How does this work out? Instead of one rocket they will have to launch a dozen or so rockets for one visit to the moon. Why did they choose this option to begin with? And is cost per time on moon not a bit misleading, just stay longer and this cost goes down? You obviously have to bring more food and air and so on, but is that really a significant amount? Or are there other limiting factors that prevent you from staying say a month?
Because this will be the first time in history that the cost of a launch will be mostly the cost of the fuel. This is the first fully reusable rocket in history. If you had to throw away a dozen tankers it wouldn’t make any sense.
Also being able to bring 100 tonnes to the surface of the moon is a fantastic reason as well. Everyone can bring a set of golf clubs and balls. Heck we can setup a little driving range with the extra mass allowance.
Notably, we don't need to bring 100 tonnes to the surface of the moon. Or golf clubs. Stable hypergolic fuel would be useful, but there are no plans for that.
NASA has stated they want to maintain a long term presence on the moon. If we take them at their word then we absolutely do need to be able to bring 100 tons to the surface of the moon.
Water, food, air, parts, habitats, ..etc. All of that adds up. Super Heavy lift capability and refueling will be vital to making those plans feasible.
How many flights do they want to get out of each rocket? For Falcon 9 the current record seems to be 18 which would be about one moon mission. They will have to go far beyond that, otherwise it would essentially be an expendable system - one rocket, one mission, just with a couple of launches each costing time and money and probably increasing the risk. Then again, if one does the accounting in terms of mass delivered to the moon, it would probably look more favorable even if they could only get one mission out of each rocket.
It’s not just the goal it’s the whole point. I’m not saying it will be achieved but that is the reason it exists and every promised capability is predicated on full reusability.
Not just a dozen. Current estimates say closer to 20.
It makes the notion of ss cans supporting Mars colonization a bad joke. The cans might be just barely adequate to support a Lunar outpost. The "gateway" concept is another bad joke. It is in plans solely because that is the closest to the moon that SLS can get to. It isn't legitimately a gateway to anything: stopping there makes getting where you really want to go substantially harder. The only legitimate place for a gateway would be in high Earth orbit, because it wouldn't require extra fuel to stop at it and then get moving again.
Mars landing is actually less energy intensive the moon landing.
SpaceX is already launching 100 times a year. Starship is supposed to have even faster turn around, launching multiple 100 times per year doesn't seem crazy, specially as current launches require complex iteration, unlike pure fuel launches. Its likely closer to 16 then 20. And optimizing the process and efficiency it will be less then that.
You end up landing around 100 tons. So you can potentially do 1000+ tons a year, and that is before you even go to having many ocean launch pads.
Ok not enough for colonization, but its a damn good start.
Not even enough for a Mars outpost, never mind colonization. The story about ferrying 100 people to Mars in a can is 100% lying; they might fit a dozen. And there is literally nothing on Mars worth refining and exporting home, not even the engines on the cans that got them there; so those would pile up.
The "Mars colonization" story is purely to pump up stock price, just like the "full self driving" that was supposed to enable you to farm out your car during the day for taxi service. Musk hyped that one hard.
Landing a single Starship on Mars literally is already an output if we want to be exact about it.
The idea that the Starship architecture isn't enough to have a small base on Mars is just nonsense.
> The story about ferrying 100 people to Mars in a can is 100% lying; they might fit a dozen.
As with everything 100 was an inspirational goal, once you have good infrastructure on both sides and everything optimized for mass transport. And yes you might be right, 100 is to optimistic. He didn't sign any contracts based on those numbers, he promised nobody that number. Its literally an inspirational goal with a low chance of success.
> they might fit a dozen
Damn, a dozen is amazing.
> And there is literally nothing on Mars worth refining and exporting home
Nobody claimed their was ... but you are really good a fighting straw man.
> "Mars colonization" story is purely to pump up stock price
That just proves that you don't have the first clue what you are talking about. Musk literally admits that Mars colonization isn't gone make money. The reason they want Starlink is because they think that can actually make money and support large rockets so they can use it for Mars. Musk things he will spend his private money on Mars colonization. Pushing Mars is literally the opposite of stock price pumping.
"Inspirational goal" is a lot of syllables for "lie". Make no mistake, nobody who understands ever thought they could take 100 people in there without freezing them. Musk said it because he thought it sounded good, fully aware it is impossible.
He also knows there can be no colony. So, every falsehood promoting it is a lie.
Re-usability was once a 'lie' Starlink was also 'lie'. Their high launch rate was also consider a 'lie'.
100 people would mean about 10m3 per person. That sounds like more then some prisoners have had in isolation cells. Of course wouldn't be comfortable necessary, and in practice you likely wouldn't do that way.
Of course this talks about a situation where there is lots of infrastructure on both sides. No need to bring extra food or equipment. A pure crew ship. Near perfect system of water reuse and so on.It also presupposes some understanding of solar radiation or much better cancer treatment.
In addition you can think of a number of ways to expand volume.You can potentially stretch the ship, or widen the ship. You could have inflatable hubs to temporary create extra volume. The earlier version of the ship when that 100 number was first talked about was also much bigger then the current one, the ship designed has changed because they realized lower cost per stack and higher re-usability made more sense. Maybe it would require medically induce sleep (bear style).
100 is of course inspirational and might be off by a factor of 2-4x but to act like this statements are some unforgivable lie is ridiculous. Specially because there is are no contracts signed or promises made, its literally just 'this is our long term goal'. Complaining because a ship can 'only' transport 12 people to FUCKING MARS is just insane to me.
And in the end the cost per person is what actually matters, and that is what they are trying to reduce systematically. If you actually listen to Elon that's what he talks about most and what has always been the main driving goal. He talks far more about that in the interviews about this, the actual number he threw out are just estimation, and he makes that very clear. He even makes it clear that they don't know how to get there yet, they literally just working towards it as best as they can. 100 per ship is just one of many estimated numbers. A million people to self sufficiency. 1000 ships operational. Many others. All those numbers might be very wrong and Elon would admit as much. Its not the 'gatcha' you think it is.
And notice how you didn't defend your ridiculous 'pump-and-dump' nonsense.
Liars typically lie for reasons. Some are just pathological, but Musk has visible reasons. He lies a lot, so is seeing which stick and repeating those.
Nobody mentioned "dumping". Please do not make things up.
The problem with EVA on the moon is the reliability and endurance of the space suits. Even if HLS delivers, there could be delays simply because there are no suits. When you consider the near rectilinear orbit having a seven day period, then bad suits are a deal breaker for the entire mission.
Conversely if you have reliable payload to the lunar surface, delivering special-use lunar escape vehicles to keep on standby is a better option then having the entire mission pay an ongoing cost for what should be an exceptional and unlikely scenario.
The problem of "we need to get off the moon now" is "okay, but where are you going and what's going to be there that's more useful then where you are?"
It's not unreasonable to note that a medical emergency would be much better dealt with on the moon - where you have gravity - then in orbit, where you don't. Whereas if you need to bail out and get to Earth fast (which you can't) then you'd be better off just dropping a vehicle which can do that onto the surface.
It does seem like quite a leap from the FTS triggering before reaching orbit to refueling, doesn't it? My hunch is that whatever happens, we'll see scenes of SpaceX people clapping and cheering and SpaceX fans calling the flight a success. From what they tell me, no SpaceX launch has ever failed.
Test flights are a very different beast. Early tests can be expected to fail; some are supposed to fail ("destructive testing"). Explosions and other failures become much more concerning later in the process; for example, Boeing's Starliner's latest test flight was supposed to demonstrate everything was working correctly. It failed to do so.
In the two Starship launches so far, SpaceX was very clear with expectations in advance. Each likely has dozens of objectives. The second flight very clearly accomplished more than the first; a successful test of the launchpad mitigations, a successful test of all first-stage engines staying lit, a successful test of separation, a successful test of the second-stage engines all lighting, etc.
Because Saturn rockets cost 1.3 billion dollars EACH.
A test starship is nowhere near that, though we don't have exact numbers. Probably closer to $100 million.
Also SpaceX is trying to solve a much harder problem. If you would have asked that Saturn team "Also, land all the stages of the rocket", the likely answer you would have got is "Screw off, you're insane" or "Give me 100 billion dollars".
Also getting Raptor engines to work. The second Starship test was a massive achievement because the SuperHeavy Raptors all worked. That's an engine design with numerous advantages which wasn't practical when the Russians tried it, but might now be practical (certainly looks to be from the test) because control systems technology is small and powerful enough (i.e. similar to how modern fighter jets fly in aerodynamically unstable regimes requiring active computer control - we have them now because we have the computers which can do it).
https://en.wikipedia.org/wiki/Apollo_6 "The damaged third-stage engine failed to restart for trans-lunar injection... Despite the engine failures, the flight provided NASA with enough confidence to use the Saturn V for crewed launches..."
Here's a fun one: They tested the Saturn crew escape system. The booster was supposed to blow up, and demonstrate the crew would survive... but the test went wrong, and it blew up early, when it shouldn't have. The crew abort worked, so test failed successfully.
Apollo 1 was very much not production hardware. "The Vintage Space" channel on YT has a good rundown, "Duplicate Apollo Spacecraft". They didn't lose any crew on production hardware, although 13 was close.
The second version was already starting production when three people died. There was never any intention to build any more of the first one, or to send it beyond low Earth orbit.
Changes were made based on the fire. The capsule was “production” in the sense that it was going to carry people. It doesn’t need to be mass produced to be “prod”. It’s prod like “this instance matters”.
Apollo 1 should have been production like it mattered. But instead the first prototype was pressed into service because the real one wasn't ready yet. The fire was proof.
No Saturn V launch failed. The very first all-up test of the Saturn V, Apollo 4, was a complete success. Apollo 6 was mostly a success, aside from the failure of the S-IVB to restart, and no part of the vehicle was lost. Every crewed launch of the Saturn V was a success, the Apollo 13 failures were unrelated to the Saturn V. For the uncrewed launch of Skylab on SA-513 the booster's S-IC and S-II stages worked normally. The third stage was Skylab itself, a converted S-IVB. It reached orbit successfully despite sustaining severe damage resulting in the loss of the station's micrometeoroid shield/sun shade and one of its main solar panels.
The "accidental abort test" was launched on a Little Joe II, a simple single-stage solid rocket motor, not a Saturn of any variety. This booster was unrelated to any Saturn hardware.
So, if Starship killed a crew of three in a pre-launch rehearsal like Apollo 1 did, you’d be on here defending it as not a problem?
If the Starship second stage failed to restart causing it to fail to get to TLI, or tried to take out its manned crew like 13 did, you’d be claiming it’s still a sterling safety record?
You’d have considered this test a success if it reached orbit “despite sustaining severe damage” on the way up?
Come on.
> Every crewed launch of the Saturn V was a success
Fine. Same for Starship, so far.
“My hunch is that whatever happens, we'll see scenes of Apollo people clapping and cheering and Apollo fans calling the flight a success. From what they tell me, no Apollo launch has ever failed.”
a) Those people with sliding rulers and navigation computers also had 2.5 % of American GDP annually at their disposal, which is several orders of magnitude more than anyone now has. (Be it SpaceX or Boeing or whoever...)
b) The Apollo program actually cost not just money, but human lives = a much worse outcome than just losing a test rocket. And Apollo 13 crew was very lucky to have returned to Earth alive.
c) Losses of test hardware can only really be somewhat prevented by being extremely careful and pedantic during development, which takes time, and guess what? More time spent obsessing about every single detail = more money spent on development. It is entirely possible that the "hardware is expendable" approach is much cheaper than what you would like to have.
If a test flight doesn't achieve the testing objectives, that's a failure. No one would argue that failing to find a bug before putting software in production was a testing success just because all the tests executed without errors.
> If a test flight doesn't achieve the testing objectives, that's a failure.
Demonstrably incorrect.
Examples:
https://www.youtube.com/watch?v=AqeJzItldSQ is a Saturn launch abort test that failed. It failed in a way that they were able to determine that intended test would have worked, though. 1:20 for the meat of things.
https://en.wikipedia.org/wiki/Apollo_6 also failed to achieve its objectives; "Despite the engine failures, the flight provided NASA with enough confidence to use the Saturn V for crewed launches; a potential third uncrewed flight was cancelled."
All that aside, SpaceX was quite clear that the latest Starship test had multiple objectives, and that "successfully splashdown near Hawaii" was deemed quite unlikely. It successfully demonstrated a number of items, including fairly critically the launchpad changes. It wasn't one test; it was a bunch of tests in one flight.
There are multiple categories of objectives... Objectives that motivated the test flight. Objectives that are expected to succeed. Objectives that you threw on because "if the $xx million object is still intact it would be nice to get some useful data, and the FAA wants a complete flight plan anyways".
If that last category doesn't succeed that doesn't mean the test flight was a "failure" from the businesses perspective. They still got what they wanted, they just didn't get the icing on top.
The test flight that destroyed the pad is properly categorized as a failure. The flight termination system was expected to work. They expected not to cause that much damage to their infrastructure and surroundings, their relationship with the FAA, their ability to get licenses, etc. To argue that it wasn't a failure, you have to argue that the flight termination system was in the category of systems where a failure was considered acceptable. If that was the case, everyone involved in launching that flight ought to to go jail for recklessly endangering the public.
The most recent test flight though seems to have been a pretty resounding success. Everything that they said they really wanted to see happen, happened. Yes, both stages had failures in "we might not even get here" test objectives after that. That's ok.
If I remember correctly there has been a couple of falcon failures, it should be noted that the starship project is is still well in the development phase.
The success criteria for integrated launch test 1 was to clear the launch pad (which it nearly destroyed) test 2 was get past the stage seperation, which it did.
Spacex have a very fast cadence for tests and seem not to make the same error twice. The best test environment is really trying to fly the ship.
Launch one really was a comedy of errors in the launch platform.
In launch 2 the booster did exactly what every other booster by everyone else (except the falcon 9) does. Got it's payload to the target altitude before separation.
The second stage reached space.
The N1 platform didn't do any of that.
You have no idea what a testing platform looks like, and are too used to NASA one shot rockets that cost 3 billion each just to make sure nothing goes wrong.
> The booster exploded after separation, which is never a good sign. Normal boosters for modern rockets don't do that.
It exploded while attempting to test its landing maneuver. If it just turned off the engines and dropped itself into the ocean like a normal booster, it likely would not have exploded (for one thing, there wouldn't be any fuel left in it being saved for landing).
Well it's not a normal booster. It's a test booster. Also normal boosters don't do a flip while getting blasted with rocket exhaust.
SpaceX clearly has a winning method, as they have a success rate of 99.3% and hold the record for most consecutive successful launches at 253. Second place is Soyuz-U, which had 112 consecutive successful launches and an overall success rate of 97.3%. SpaceX has more consecutive successful booster landings (173) than any space program has had successful launches.
A few people have slosh modeled the booster flip around duplicating observed speeds and accelerations and surmise the following. The flip around was too rapid causing slosh to one size of the booster. In addition there was negative acceleration that would have allowed the remaining fuel to experience zero gees pulling it away from the bottom of the rocket. When the engines fired back up it would have hit the bottom of the rocket with something between 20 and 100 tons of force. Based on SpaceX description, the FTS was not used.
The second stage at least appears to be oxygen leakage. The graphs shown on flight day started showing a more rapid depletion of oxygen after second stage lighting. SpaceXs language was something like 'flight was unable to reach orbital insertion and was terminated, pointing to the FTS being used.
SpaceX is taking a very different approach from those of other launch companies, taking a far more rapid prototyping style approach to development, knowing that the first few iterations are going to have problems that they can fix in the later versions.
This sounds wasteful on paper, but in practice it is much much faster and amazingly enough cheaper. With traditional rockets you never make enough to enjoy economies of scale, but with SpaceX's approach they've dropped the cost of the engine by about an order of magnitude over just a few years, and it was already a very inexpensive engine. For the cost of a single RS-25 you can buy 400 Raptors.
Exactly. With traditional development it is very expensive if you find a core problem in late development. In rapid development you expect to catch it early.
Seems to me it's more the inverse - Elon bashers trying to find a way to paint everything he's ever done as a dumb failure because they hate some unrelated thing that he did. Not saying the guy is perfect, but if he is a fuckup, you should be able to make the case without disingenuous arguments like misunderstanding the purpose of test flights.
Multiple iterations of test flights that are expected to fail is a much faster way to develop impressive tech than spending 3x longer doing on the ground analysis of every detail of everything because you can't bear the PR hit of something that can be painted as a failure.
I think you're showing a lack of understanding of Spacex's fast development processes but as an aside the word cue (rather than queue) is used when we are referring to a sign or signal given by something or someone.
I know nothing about rockets but bits of project management: it's common to break down projects into smaller parts and derisk designs/implementations by testing each piece.
The refueling team might be ready to test, even though the "don't explode" team are still working on it.
This is roughly equivalent to watching a developer work and insulting them when their code doesn’t compile. Nobody who writes code cares, that’s just what writing code is like. You could spend a ton more time writing code trying to get it to compile without errors ever, but that would be a whole lot more pointless work.
There are costs and then there are trade-off costs. In the long run, the trade-off costs of slow-moving perfectionism are FAR higher than the cost of the ‘fail fast and early’ culture at SpaceX.
This is pretty interesting, but Id be surprised if it actually happens on the next flight. Depending on the cost of the tanks/fittings/machines, it could be a fairly expensive loss if Starship doesnt reach orbit, which seems fairly likely still. Their last launch was impressive, but Id be wary to put a payload worth more than a few pennies on the next launch
It's fantastic that the Super Heavy booster fully completed it's mission! Much bigger deal than the ship itself failing.
Before that last flight it seemed like engine reliability wouldn't get solved. But now they have a clear path to orbit.
I doubt the heat shields will hold up on the first several re-entry attempts but there's been recent sightings of a new heat shield that has tiles about half the size. Maybe smaller tiles will have less lever action and will have 4x the fasteners.
>Maybe smaller tiles will have less lever action and will have 4x the fasteners.
This is still the number one problem with Starship. There were all these wild claims of an exotic new liquid cooled reentry system at the beginning. But because physics they ended up going right back to using ablative. They'll suffer the same fate as the shuttle for it. Nothing has fundamentally changed in ceramic or adhesive technology since then, and the lack of aerodynamic control means they will have to survive even steeper descents with greater thermal load. I imagine the idea of Starship as an earth return vehicle in general will probably be abandoned, so they can optimize it for interplanetary transport and lunar operations.
Of course the problem with this post is that the Starship heat shield isn't ablative, nor does it share the problems with the Orbiter heat shield (Needing glue to attach every single unique tile to the body of the ship.)
Yes, it is. There is no such thing as a non-ablative reentry vehicle. The tiles are effectively no different than what was used on the shuttle.
>There are literally wings on the ship.
Starship has no meaningful aerodynamic control beyond what is required to perform the flip. It has no ailerons or elevators. It falls to the earth in a completely ballistic trajectory.
Insulating tiles are not an ablative heat shield, they are a thermal soak heat shield. Ablative heat shields are non-reusable as they work by slowly burning off material which creates a cooler boundary layer between the plasma and the heat shield. [1]
Sure, everything going through the atmosphere at supersonic speeds will lose at the very least a couple of atoms here and there, but that was not the point and that does not make thermal protection tiles an ablative heat shield.
Thermal soak heat protection: the protective material absorbs - soaks - the heat, becomes really hot, and after the process need to dissipate the heat. Also - which is important - the heat capacity of the material should be enough to absorb the whole heat flux going into it. Also - thermal conductivity of this protection should be such that the protected material behind it won't get too much heat. For this kind of protection to work you want small temperature differentials - less heat flux - and small time of heating - otherwise the material will become too hot. However - as materials have varying thermal conductivity - the thermal soak is always present to some degree.
Radiative protection: the protective material heats up so much it stops accepting more heat, because it radiates heat back with the same speed. After the process the surface of this material is really hot. Important requirement - low thermal conductivity, as the high temperature on the surface shouldn't get behind the protective layer. Also known as refractory protection. Space Shuttle thermal protection is an example.
Ablative protection: the surface of the protective material releases its material in the form of gases, and this gasification process cools down the material. The material gets consumed, that's the main problem with this cooling approach - neither big thermal capacity nor small thermal conductivity are needed. Early Merlin engines used ablative cooling.
"A second enhanced version of PICA—called PICA-3—was developed by SpaceX during the mid-2010s. It was first flight tested on the Crew Dragon spacecraft in 2019 during the flight demonstration mission, in April 2019, and put into regular service on that spacecraft in 2020." .
"Starship's heat shield, composed of eighteen thousand[131][132] hexagonal black tiles that can withstand temperatures of 1,400 °C (2,600 °F),[133][134] is designed to protect the vehicle during atmospheric entry and be used multiple times with minimal maintenance between flights.[135] The tiles are made of silica[136] and are attached with pins rather than glued,[134] with small gaps in between to allow for heat expansion.[2]"
which makes them a kind of radiative or refractory protection.
>Neither the space shuttle nor Starship use ablative heat shield tiles.
They are effectively ablative in the sense that neither vehicle has (or will) be able to complete successive missions without massive replacement of damaged and missing tiles. The fundamental approach is not suitable to reusability, as we learned with the shuttle.
First of all, that's not what ablative means. Tiles potentially falling of does not make the heat shield ablative. Because tiles falling off is not a the heat transfer mechanism, rather a mechanical failure.
The Dragon Capsule for example has an Ablative Heat-Shield. But that doesn't necessarily mean it can't do multiple missions in a row. It just depends on how the shield is designed. The Dragon could potentially do many earth missions without replacing the heat shield.
Second, you are wrong in that there is anything fundamental about Starship or Shuttle heat shield not being able to fly multiple missions. If the tiles are still attached and not damaged, then all that has to happen is for the tiles to cool down. After that they are ready for another flight, meaning the tiles are not ablative.
Now experience on Shuttle has shown that if you are not careful tiles could fall of or be damaged. Damage can be reduced in various was and Starship without an external tank is already much better by design.
Additionally Shuttle had to glue tiles to a fragile aluminum frame making the installation very hard and the tiles very fragile. Starship on the other hand uses welded studs on a steel frame. So even if a tile is lots, the steel should still hold up pretty well. In on case Shuttle was saved because there just so happened to be steel under a damaged tile.
So you are right, heat shield is one of the biggest issue that could cause problems with rapid reputability. You are wrong, the tiles are not ablative cooled. But Starship tiles are totally different then Shuttles, they have made many improvements in the heat shield and its construction and in the heat shield tiles themselves.
Starship can likely survive even with a number of missing tiles if required. In some position tile lose can certainty be fatal.
Starship has another advantage over Shuttle orbiters - orbiters were about 80 tons when landing, while Starship is about 120 tons empty, but has much bigger size - diameter and length, which makes it braking higher in the atmosphere where the heat flux is smaller.
> I imagine the idea of Starship as an earth return vehicle in general will probably be abandoned, so they can optimize it for interplanetary transport and lunar operations.
Starship will need several launches of methane+oxygen to travel beyond LEO. That model requires a reusable orbital tanker to make sense economically.
Most of the engines are on the booster. The upper stage is the cheapest part of the entire rocket. At a worst case of 2 million per engine you're talking about 66 million dollars for the booster.
I honestly don't understand this whole post chain. The booster needs to survive because it is the most valuable part of the rocket and yet we are supposed to praise it for exploding? The hot staging concept isn't viable over the long term because it goes counter to the goals of reusability.
I don't need people to rewrite history by claiming that if the booster of the SLS exploded, it would be considered a success since nobody intends to reuse it. Yeah, that is how you get a two billion dollar launch tag. You can't convince congress to drop the SLS if you keep losing boosters.
They attempted a novel hot staging sequence where the booster grid fins interact with the second stage exhaust to rotate the booster. The booster rotated too violently, and shook up the tanks like a can of beer before exploding. They need to improve the control systems so the rotation happens more smoothly.
I wouldn't praise the booster for exploding, but I would praise the engineers for getting it all the way to staging without engine failures. That's all most boosters are expected to do.
SLS isn't expected to explode because it's based on space shuttle parts that stopped exploding decades ago.
> There were all these wild claims of an exotic new liquid cooled reentry system at the beginning.
Its not that wild. That technology is likely used on certain military equipment.
I was certainty something not tested at that scale but it wasn't a crazy thing to think about.
> But because physics they ended up going right back to using ablative.
They are not ablative.
> Nothing has fundamentally changed in ceramic or
What's your evidence? Have you done lots of study on Space Heat shield? Please share your findings.
> adhesive technology since then
That just wrong. Starship uses mostly welded studs steel frame. Totally different from Shuttle.
> and the lack of aerodynamic control
They have sufficient aerodynamic control. What evidence do you have that they don't? They have shown simulation of this before. I'm gone go with SpaceX on this unless you show me some simulation that shows insufficient control.
That 'clear path to orbit' depends on what the performance of the raptor engines is, as flown. Getting the first stage to work on all engines was a big achievement, but how effectively those engines are working is another big part of the puzzle.
That's the whole philosophy of spaceX and explicitly starship though, right? I mean they literally lauched a water tank up 100 feet and hovered it back down as a demo, then immediately scrapped it and proceeded to build 27 Starships, when not a single one has reached orbit.
building the header tanks in the first place, and testing them is the interation style. If the starship blows up, the header tanks are the least of your worries.
Compared to the base cost of the next launch, putting a bunch of experimental tanks / pipes / valves / etc. in the upper stage's cargo bay would be dirt cheap.
And "time is money" - if you want to develop $ComplexTech fast, then you should start doing R&D work as soon as physically possible.
The “payload” is an experiment that is at most two tanks, a valve and monitoring equipment. However it is pretty clear they will use the existing LOX main and header tanks and valves already present in every Starship. This will meet the requirements of NASA’s 2020 $53 million challenge to “transfer 10 metric tons of cryogenic propellant, specifically liquid oxygen, between tanks on a Starship vehicle”[1] as the smaller header tank holds roughly 20 tons.
If you are already attempting to get into orbit it makes sense to include this experiment in case you succeed because you save the time and cost of an entire launch and might get a $53 million award while advancing a key requirement for HLS, a $2.9 billion dollar contract and the current core mission.
This experiment has been planned for years, Starship was designed to do it and it makes sense to do it now. SpaceX clearly knows what they are doing. Unfortunately HN is terrible on this subject.
Cryogenic fuel transfer requires a bit more than that.
The big issue is that unlike all fuel that has been moved between tanks in microgravity in the past, SpaceX isn't storing their fuel in a flexible tank. Instead, they have the fuel and the pressurant gas in the same tank. Under acceleration (gravity or otherwise), this is not a problem, because the fuel pools naturally "down", with the pressurant above it.
However, as soon as the acceleration stops, there is no more down. Instead of having a bunch of fuel on the bottom and pressurant above, the tank will contain a chaotic mixture of floating gas and liquid.
The minimum setup for fuel transfer is a maneuvering system capable of a very long, weak impulse (to provide down), and then some kind of pump that moves fuel, because the force provided by the weak impulse of a maneuvering thruster is not enough to do it on it's own.
Rotating the pair of (tank and vehicle) around a common center, and pumping "up" through the center, could work. But the pair would be very off-center most of the time, and unstable unless attached end to end.
Flexible couplings are hard to keep flexible at -200 C. But the real issue is keeping the fluid pooled around the pump intake, and not distributed in blobs throughout the tank, interspersed with gas.
Could you try to circularly pump a mixture between the two tanks and create some kind of filter in each tank?
The idea of circulating a mixture & taking one you need is for example how donating blood plasma platelets works. If we can separate fuel and pressurant without too much fuss, a similar non-propulsive technique for a cryonic fill might be possible?
Mixing fuel and oxidizer is a good way to get a dramatic explosion. Good if you wanted the explosion, not so good if you wanted vehicle and tank to still exist afterward.
I think the point is that the liquid/vapor mixture is still a fluid, just a weird one - you can pump it with the right type of pump it would just be more akin to ventilating a room to get dust out, for example (i.e. moving gas to move floating solids).
I haven't seen any plausible indication of how they will manage what is called "ullage".
Putting propellers on electric motors inside the tanks, to make fluid circulate axially around the center line, would propel it to intakes on the circumference, with a growing bubble running down the center. Then they would not need to accelerate the vehicle throughout the process, which alternative seems wholly impractical.
It would require clever design of the anti-slosh baffles (never shown in cutaway diagrams) to be compatible with such circulation. It might be tricky to keep the whole tank from switching to tumbling end-over-end.
It's as simple as using thrusters to keep the propellant settled. milli-gee thrust (or even lower) has been shown to be sufficient for settling cryo propellant in upper stages during long coasts. SpaceX has been experimenting/analyzing settling of cryo propellant (LOx) during hours-long coasts for years, now. It's a requirement for doing direct-GSO insertion for an upper stage (or even doing any relights or deorbit burns, for that matter), which they've already done.
"But wait, it's supposed to be more complicated than that!"
No, really, they've been doing this stuff for years, and settling propellant for upper stage coasts really is virtually the same thing as settling for propellant transfer (transferring to the engine(s) for relight vs transferring to another stage... in fact you have to be MORE careful to avoid bubbles when feeding propellant to an engine than you do when transferring propellant to another tank).
https://www.youtube.com/watch?v=mVAGoWJuDKk
They still need to do the whole launch-two-starships-then-dock-them bit, plus quick connect fittings, but they already have years of experience with autonomous rendezvous and docking from operating Dragon at ISS (Dragon 2 has that capability, and it has been used for the uncrewed Dragon 2 demo mission plus the recent cargo Dragon 2 missions, plus I think it's the nominal choice even for crewed missions).
The difference is that in preparation to fire a rocket, you only need to apply ullage acceleration for a short time because after the rocket lights, that provides the acceleration. When just transferring fluid, you need to accelerate during the entire period of the transfer, because pumping fuel to another tank provides no acceleration of its own. So, you need the acceleration to be small enough not to build up to an inconvenient delta-V over the time it takes to move the fluid.
In principle you could apply acceleration for a while in one direction; and then switch to accelerating in the other direction, wait for the fluid to settle at the other end, and pump from that end, alternating back and forth. But it still consumes reaction mass, and introduces delays while switching.
Docking vehicles massing hundreds of tons is a much bigger problem than docking Dragon. The Dragon experience might not apply very directly.
Presumably the engineers actually involved all understand this (literally rocket science) much better than we do.
You can do the settling thrust near perigee, so the delta-v from settling doesn’t go to waste but increases the apogee of the depot and increases the orbital energy of the propellant.
Docking dragon is obviously similar to docking starships (Dragon berthing sensors were tested on Shuttle, broadly similar to an empty Starship). You’re right, tho, that the actual SpaceX engineers (who proposed this and developed Dragon) understand this better than random online folk.
This is very well put. There's also a second issue, which is chilling down the receiving tank quickly and efficiently enough that the fuel being transferred doesn't just flash bil and vent off into space. Like rocket combustion, this is very hard to model and sensitive to nozzle geometry, how fast you spray, the phase of the moon etc.
> as soon as the acceleration stops... the tank will contain a chaotic mixture of floating gas and liquid
The traditional solution is to replace acceleration/gravity with surface tension, using various types of Propellant Management Devices (PMDs).[0][1]
When last we saw our heroes, the stated plan was to solve the problem with milli-g acceleration via small thrusters.[2] That was 2017, but so far there's been no indication this part of the plan has changed.
A smaller impulse to rotate the whole thing, so that tanks are on different sides relative to the center of rotation, may be easier. At least the system will have as much time as needed to do the pumping after the spin-up. Then another impulse would stop the rotation.
>If you are already attempting to get into orbit it makes sense to include this experiment in case you succeed because you save the time and cost of an entire launch and might get a $53 million award while advancing a key requirement for HLS, a $2.9 billion dollar contract and the current core mission.
Not sure what you mean. They have to have this stuff on each Starship anyways. And they need to learn how to build that stuff. Its already built into the next Starship. And that ship (in fact the next 4) have no other reason to exist other then testing these things.
The ship is the payload. The testing is inside of the tanks of the ship. Moving fuel around inside the ship. There is no extra expensive payload in addition to the ship.
SpaceX's Raptors cost about $250k each according to some leaked sources. Given there are 33 engines in the booster, you get 8,250,000 just in engine costs. I would say it's safe to assume around 30% of the cost of flight is in engines, so probably around another 5,775,000 for the rest of the craft bring it in at around $14M for just the booster hard costs. That's not accounting for the $100m crane they've built, labor, propellant, nor the Starship itself which has another 9 engines.
Keep in mind that the RS-25's cost $100m each. If it was atlas, the engines alone would cost $3.6B.
initially the merlin engines were $2m each, with raptor v2 coming in at under $1m, and they are pushing out 1 Raptor v3 a week now, so i'm sure they've come close to their goals. You might want to push that number up by 50% to get a more realistic estimate, and then by another 100% to include labor, propellant, etc.
$44m per booster starts to sound like a more reasonable number.
The number of iterations Raptor has seen is kind of insane. V3 seems like it’s a substantially different beast compared to the original.
I suppose that’s par for the course when bringing a previously lab-bound type of engine into practical use, but still. Did Merlin see iteration at such a pace prior to being fitted on Falcon 9’s? Raptor looks to be on track to be in a considerably more refined state when Starship goes into service than Merlin was at during the same point with Falcons.
There's a video that i can't find, where they show Raptor v1, next to raptor v2. The raptor v1 has all these wires, and tubes and looks crazy, next to it, the raptor 2 looks super sleek and not that complex. They ended up molding everything they needed straight into the block itself. Can only imagine what the v3 designs were since they are now all internal.
But what you get at the end with something like 3000 parts in it's BOM, to something like 20 parts in the BOM, because most of the parts were deleted and integrated directly into the mold.
Merlin saw much less major iteration, but with that it's worth considering that there is a lot more experience with Kerolox engine design out there (plus a much simpler combustion cycle). Plus it was based on a NASA reference design. I do recall from Eric Berger's Liftoff book, they struggled with the nozzle design though. Very early Merlin had an ablative nozzle.
I suppose the better way to put it might be that Merlin's iteration was more in getting the production sorted out, whereas Raptor is iterating everything based on lessons from Merlin and previous Raptor iterations.
It's hard to say from the outside because of all the optimism. They are targeting $250k per engine, and have thrown around numbers like $5-10m for the fuselage(?).
From what I understand, the engines are still >$1m each, but coming down as they ramp up production speed and have radically simplified the engines with V2. The body is probably also much higher than the target range, but bearing in mind that it's just stainless steel and relatively well known manufacturing techniques, and not aluminium going through complex and expensive manufacturing techniques, they're probably well under any other typical rocket. I'd assume even significantly less than a new Falcon 9, which is already the low end of the industry in terms of price.
Another thing I'd bear in mind is that many of these ships never got completed, on purpose. There have been explicit "pathfinder" builds, but even with the "real" ships most never flew and were pretty much about working through techniques, tools, materials, etc. These won't have needed a full fit-out and will have been cheaper.
If the plan is to scrap the rocket no matter whether it succeeds or fails, does it cost anything? All of these seem like data gathering missions to me.
Yes, of course it has a cost. Material has value. Even Elon doesn’t have unlimited capital. Even if raw material was “free” there’s still the opportunity cost of simply selling the material and pocketing the cash. The test may be worthwhile but that doesn’t make it free.
It's amusing that you posit the notion that instead of launching the rocket (its entire purpose to exist), they might disassemble it for scrap to save some cash.
They built the rocket out of raw material which they paid for. I’m not sure what’s hard to follow here. Rockets aren’t free. How is that controversial?
SpaceX has built and scrapped 17 Starships, 14 of them without even a static fire. They have scrapped four Super Heavy boosters, three of them without firing.
Test flights require fuel, planning, approval, and of course flight hardware. None of that is free.
For this type of operation I think asking about the material cost isn't very useful considering how vertically integrated they are. They're still paying the workforce whether the test happens or anything is built. The input raw material is pretty close to "free" as it comes in as giant rolls of sheet steel.
I think the issue you seem to be missing is that the marginal cost of materials that go into building a rocket is very low. The fuel cost is similarly a small percentage of the cost of building a rocket. The cost comes from the large workforce required and the low flight rate.
Approximately every stage of every rocket before spacex started landing them was “lost”. Test flights are part of development costs. Nobody at spacex is particularly concerned with test fights being test flights.
Don't know the cost but the rate of development is so fast they don't want to keep the old ones anyway. It's not like they would keep it and use it for anything except scrap metal. The technology is so out of date compared to the models waiting to go. Blowing it up or ditching it in the sea is basically an easy way to get it off the pad to make room for the next one.
The costs get kind of complicated since various bits get out of date and have different value.
For example, there is speculation that a finless "Starship" that had been seen at the site some time ago which now appears to be being scrapped without any use was thrown together in case S25 was not ready in time for the second flight. So while construction wise they spent money, is that money that was part of the test cost?
Similarly, they're moving to Starship V2 and Raptors are moving to V3, making the previous hardware obsolete. But since they can still gather data from launching the older hardware, they will launch and lose it since scrapping is supposed to happen anyway. So at that point losing the vehicle in flight hasn't cost them much more than just scrapping it.
However, since you probably mean actual construction cost, the boosters must clearly be expensive, thus their interest in getting those working even if it means sticking sacrificial Starships on top.
I'd guess each unit is probably around $40-50 million each. Still revolutionarily cheap per kg, but certainly not so cheap that they can keep endlessly throwing them away on incremental steps.
I've been on a bit of an Apollo kick lately, and reading some of the history of the American space program in the 1960s and 1970s was depressing. Those people were tapped into something bordering on divine.
It was depressing until I realized: SpaceX is absolutely carrying that spirit.
Remember when all the experts said it was impossible to ever land their first stage? And then that it was impossible to ever make that economical? And then remember when Elon teased Starship (back then it was called BFR) and all the naysaying that went along with that?
They've just kept going. Just an absolutely break-neck pace. Falcon heavy was barely supposed to even work, and now it's not even news when they launch one.
edit: ha! I think there's actually a falcon heavy launch tonight!
We won't know for sure unless SpaceX goes public, but leaks suggest the marginal cost of a reusable F9 launch is below $20M and the sticker price is $67M, and that goes up fast if you want vertical integration etc.
Not really. SpaceX survived before they raised a lot of money for Starship and Starlink. They didn't have a lot of money and at that point they couldn't really sell at a loss. Their programs, Commercial Cargo cost them more then expected. And Commercial Crew wasn't anywhere close to making money.
SpaceX sold launches at around 60-70 million $ and that made it profitable. Once the proved out reuse, they were able to get investors. My contention is that unless they could actually show reuse they could have never raised they amount of money they did, it wouldn't make sense.
Another way of thinking about it is, what based on basic principles is the cost of building these things. Various people have estimated this stuff. 20-30 million $ for the first stage with engines, 5-15 million $ for the second stage, 6 million $. Probably 20-30% overhead for operations and fixed cost.
Now things are different. The first stages are going on 20 reuses. The second stage is now being mass produced pretty significant volume, so price goes. Fairing are reused also. You have the same size operations team that is far more efficient. A team that used to do 10 launch now does 50 launches. Moving to automated range safety is one big such optimization. The launch pad utilization is far higher.
So most people who look at this come out for with a marginal cost of about 15-20 million $ per launch. You can be conservative and say 30 million but it hard to come up with reason why it should be so high. At the same time they are still selling launches at 65 million. And in addition to that, they have many special launches that are likely earn them more, DoD launches, NASA launches, Crew launches and Falcon Heavy launches.
So I think it really, really hard to argue that SpaceX core business isn't very profitable. You would basically have to claim that first stages get totally rebuilt from the ground up and all engines replaced. But we have very good evidence that this isn't the case.
Now of course that doesn't mean SpaceX is profitable, as thanks to the re-usability success, they invested heavily in Starship and Starlink. And those are of course unprofitable investments for now. Starlink is starting to turn around, but Starship is quite a bit away from that.
What can maybe be argued is that if you only had say 10 launches a year, re-usability wouldn't be worth it for various reason.
It is baffling how many HNers in this thread don't understand what "test flight" means.
Yeah, for SpaceX, experimental hardware is expendable. Yeah, it is not very typical in space industry. But it is a tried-and-tested approach, which gave them the Falcon 9, the most reliable and technologically advanced launcher of today.
I don't have any problem with them adopting a test flight heavy methodology, however it is extremely misleading to suggest that this is the methodology which gave them the Falcon 9.
The falcon 9 succeed on it's first launch, it was not a test flight heavy program.
The falcon 1, SpaceX's only orbital rocket prior to the falcon 9, did fail on it's first three flights, however it was never intended to and that nearly bankrupt the company. They destroyed third party payloads on flights 1 and 3, because these were intended to work, not be test flights.
Long after it was in production the falcon 9 did begin a "test-flight" heavy program, but that was for developing the ability to recover boosters after they had successfully delivered a customer payload in an operational flight, not for developing the rocket itself.
OK, I could have been more precise: the "hardware rich" program is what gave them the current reusable configuration of Falcon 9, Block Five. Which is what I would describe as the most reliable and technologically advanced launcher on the planet.
The series of failures when attempting to land for the first time was spectacular.
You also see dependencies early. Even if you never get to use the refuelling mechanism, you’ll gain data on how the reserved fuel sloshes and alters flight characteristics. This refines your models and may give clues as to efficiency gains that otherwise would have been an afterthought or, more likely, scrapped in the face of a deadline.
All of the Falcon 1 payloads were expendable (which includes low-priority). It was a test vehicle conducting test flights in all but name. Had they continued developing it instead of pivoting to Falcon 9, it would have been its own test vehicle.
Suppose that the eventual production vehicle has a fairly different design, a different name, and it succeeds on its first flight. Would it then have used the same methodology that resulted in Falcon 9?
I'm only asking rhetorically. The Ship of Theseus is an interesting philosophical question, but the way you define "methodology" shouldn't depend on your answer.
> It is baffling how many HNers in this thread don't understand what "test flight" means.
I've been seeing parallels to this growing at an odd rate. Where context is removed and HN only cares about results at TRL ~7.5+. Its often quite baffling to see systems/models designed in academic spaces with minimal compute resources to systems/models with billions of parameters and millions of dollars in funding. Or to see TRL 2/3 projects be dismissed because they are not >TRL 6. I wonder how people that make these types of responses think research and development happens if you must catapult one's self from a theory to usable product in a realistic environment before it becomes of any interest. It seems rather anti-scientific tbh. Not what I'd really expect from a crowd dominated by developers, engineers, researchers, and scientists.
As for rockets, well... exploding rockets are expected during testing phases. Obviously you want to reduce this, but catastrophic failures, or any failure, serve as great learning opportunities due to the inability to formulate a complete model (combustion instability is a notoriously difficult problem).
I think also many are interested in the subject and so do watch videos and read other sources but that these are at high level discussions and often not getting into the low level nuance that is actually necessary for solving these types of problems. But that as humans we often conflate excitement and time with a subject with expertise in that subject (all time is not equal). Personally I wonder if this is an accurate and general phenomena and exacerbated by our growing information age combined with the large number of armchair science communicators. I think all nerds, including myself, have been guilty of asserting things as facts (or with stronger confidence than they should be), often in an effort to help inform others or simply wishing to participate.
On a side note: anyone feel like it's a bit weird how low (aerospace) engineers are paid in comparison to us in software? Like not bad wages overall but there is a large gap (not looking to get my pay decreased, but the other way around)
>On a side note: anyone feel like it's a bit weird how low (aerospace) engineers are paid in comparison to us in software?
Software produces gobs of money, the likes of which the world has never seen. Aerospace as an industry may not ever be profitable. It's as easy as that.
It doesn't seem as simple as that considering revenues are above $700bn. Plus, it's not like the defense industry is considered small by any means. I'm willing to bet everyone you know (or nearly) has flown in an airplane. I'm definitely not an economist but googling around it doesn't seem like the difference in revenues is an order of magnitude. But I'm willing to believe I'm misinterpreting and/or didn't look hard enough (most certainly the latter is true).
I definitely agree that software is more profitable, but the gap is a bit surprising, especially considering the high skills and training required.
Software has almost zero overhead beyond base line business expenses. Anything that requires making real stuff depends on many more people to produce the product. They all need to be paid which means engineers and management need to take a smaller slice of the pie.
Sure but I always have a hard time comprehending these arguments tbh. Because I honestly can't tell the difference between someone who has a billion dollars and someone who has 200 billion dollars. There's essentially no difference other than a number.
But while writing this I decided to check instead of making what I thought was a reasonable assumption. Apparently the net worth of the CEOs of Boeing, Lockheed, and Raytheon are under $100m? That's a bit surprising if the numbers I googled are accurate. That would make the net worth of the two primary shareholders of BMW 1000x their counterparts. Each! I scrolled through Forbes billionaires and I didn't find aerospace anywhere but I did find pig breeding, shipping, and Chick-fil-A, candy, soy sauce, videogames, legos, in-n-out, dental implants, "Star Wars", "Billboards", and even "drones". Especially considering that there's a lot of shipping on there and a drone billionaire.
Really makes me think some of the other things are over priced tbh. Especially with how many crypto-bros are on that list.
Edit: Wait! "762 Charles Edelstenne" is listed as "aviation" but he cofounded Dassault...
Edit 2: "868 Neal Blue & family" is listed as "Defense" for General Atomics and "871 Eren Ozmen" as "Aerospace" for Sierra Nevada. "916 Fatih Ozmen" also for Sierra Nevada. So okay, maybe some are on this list but my intuition suggested defense and aerospace would have at least someone in the top 100. Surprised not even the top 500.
We can find countless examples of high paying jobs that are absolutely useless to our industrial civilisation. The answer is likely a mixture of both: salaries are not that much correlated to skill and value overall, and some industries have much lower margins than others.
Having to compete with the likes of Airbus and ULA for workers, SpaceX doesn't need to inflate the salaries that much to get top talents.
I think salaries aren't as crazy as software because the while there is high demand and limited supply, there is also a limited selection of places you can do that kind of work at, while computer people have a spot in basically everything.
For anybody else wondering, "TRL" is NASA's Technology Readiness Level, ranging from TRL 1 (pie in the sky) to TRL 9 (flight proven mission operations).
Yeah, but this is development of a brand new reusable superheavy launch system. Can't be cheap. We should keep that in mind and compare the comparable.
Looking at the Western space industry history, Starship development is only comparable to the Apollo or the Space Shuttle program - both of which would be insanely expensive in 2023 dollars, certainly exceeding 100 billion USD each, perhaps 300 billion USD in case of Apollo.
Got a citation on that $2 billion cost for each Starship launch? It's not clear what the exact cost is, but I haven't seen any estimates that are nearly that high.
Oh, they could? Let's hope they do! It seems that they're afraid to stake out the goal of these launches because if they keep it vague they can always claim a V. If they say their goal is to test refueling tech and it explodes before reaching orbit that's a failure. They were also supposed to test the heat shields last launch and they didn't make it that far. I have zero faith they'll deliver without bankrupting themselves. Musk has said they've spent about $2bn a year on Starship over two years.
And yet spacex was profitable this year.
So if it’s true that they are spending $2B per year on starship while being profitable it’s unbelievably good for them.
This is pretty cool. We need to be putting a lot more resources into space tech TBH. It should ideally be a single digit percentage of the budget/GDP as a starting point. The future of mankind really rest on it.
‘The future of mankind’ only rests on life beyond earth if everybody gives up on keeping earth livable. The biggest threat to humanity is humanity, and a colony on the moon or Mars isn’t going to fix that problem.
Not quite correct. It's useful to have some remote parts of humanity which could be relatively safe when other parts are busy making threats to each other. Earth still has some remote places - ask any doomsday prepper - but Moon and Mars will certainly add to the list.
So your assumption is everyone going to Moon or Mars is a saint. And if so - who set the standard? Pope? President? And then what do we do if they become not-so-saint? Drag them back to Earth?
The whole idea that some sort of better type humans will travel to another planet is frankly ridiculous. We don't learn from our own mistakes - see WW1, WW2, current state of affairs. If anything, we would most likely destroy Mars and Moon much faster than how we wronged Planet Earth.
On one side I can see that rich countries are perfectly happy to have offloaded their polluting industries to developing countries. On the other, it's also very obvious that we mostly end up stacking things instead of replacing them: we've never consumed as much coal as now, even with all the alternative sources of energy available. We simply do more and are more inefficient.
It really seems like on a technological level, sustainability on earth is roughly solved even with modern comfort. What remains of the problem and prevents us from implementing it is more social and political than anything...
An off planet colony would likely face the same issues of sustainability as soon as different factions start competing for resources.
If earth becomes unlivable, then by definition it can no longer support colonies.
The path to making colonies on Mars or the moon self sustaining is not even clear at this point. Starting with the simplest of fundamentals - air, water, food and protection from cosmic radiation. The prospect of growing a technical civilisation on either body, that can develop further without support from Earth is remote.
By contrast, to make earth unlivable basically means nuclear war. Climate change won't do it, biological pandemics won't do it, nor will fossil fuel exhaustion or any other localised event.
On the worst day possible on earth (global radiation aside) its still a million times better to live on than anywhere else.
In terms of global radiation making the world uninhabitable even then tiny, non-sustaining pockets of humanity would survive. At least until their life-support systems failed.
Lastly, I wonder at the need for "the future of mankind" as a goal at all.
That’s all true, but I still think it is a reasonable goal. Having the technology to be self sustaining in another world has the ‘side-effect’ of letting us be self-sustaining on earth… reducing the risks human pose to ourselves.
That said, ‘colonizing’ the artic or shallow ocean floor probably accomplishes most of the benefit for a subset of the cost and risk.
The only real benefit I see to space over the attic is that off worlding mining and production could be a benefit in itself.
If all the water on mars were melted, it would cover the planet in 100ft of water [1]. With the safe assumption of any kind of water recycling, and indoor habitats, there's plenty of water on mars, which also means there's plenty of oxygen on mars (along with the 95% CO2). The atmosphere is 3% nitrogen, and 1.6% argon, which means there's plenty of air on mars. You don't have to fill the sky with air, just the buildings.
There are plenty of things that could destroy all human life on Earth and not destroy all human life on all planets.
Also the argument taken to an extreme is straightforward. We know that massive catastrophes have caused mass extinctions that wiped out most life on Earth. This is clearly visible in the fossil record. Ergo, one of these is certain to happen again. In the extremely long term, the Sun will get hot enough to kill all life on Earth in a couple hundred million years. So Humankind is doomed if we do stay on just Earth for the very long term.
There's also the side argument that "right now" appears very close to making it possible. If Starship and the attempt at reusable rockets were to disappear there's nothing guaranteeing the progress of space technology. It's easy to see a future where we do some more footprints on the Moon and maybe later some footprints on Mars, but no permanent off-earth colony is ever established. Eventually we give up on creating such bases because they're deemed too expensive and "robots do it better" as our robotic technology gets better and better. The technology of how to do reusable vehicles is eventually forgotten over several generations and then we never leave Earth again. (Eventually resulting in our destruction.) This is a "why not now?" argument.
Smarter Every Day on YouTube recently spoke at the American Astronautical Society about this flight plan. I found it quite interesting how different it is compared to the way we used to go to the moon decades ago. He challenges the complexity of the new flight plan, including the refuelling step.
It’s a longer episode but well worth the watch if you enjoy the channel and are excited about returning to the moon.
The Smarter Every Day video unfortunately is not an authoritative video on Artemis and misses the point on several parts. It's largely a rehashing of very old arguments that basically views Apollo as somehow the height of technology.
>It's largely a rehashing of very old arguments that basically views Apollo as somehow the height of technology.
I think this kind of misses the point of the video, which was not about the technology of Apollo as much as it was the design principles that went into making the mission a success. Technology obviously is involved in that, but the argument for "do it like Apollo" is more a long form version of "keep it simple, stupid".
A good example of this is when Destin brought up the Apollo 1 capsule fire[1] which changed the speed and safety considerations at NASA. He cautions that now, before a catastrophic accident, is the time to make sure the best possible plan is being followed, simplify things that can be simplified, and get people to the moon and back safely. Something as simple as the choice to not use hypergolic fuels means there will need to be extra equipment to reignite the engines and redundant mechanisms for such a system.
It’s a rehashing because it misses the point that we’re not going back to the moon just to say we can do it. We’re going back to stay, to mine, to live there. Just swapping to an updated version of the LEM gets us nowhere and we would learn very little.
> Why did we design a system where Orion does not have enough delta-v to achieve a circularized low lunar orbit?
Because Orion was not designed to go to the moon. It was designed, ostensibly, to go visit asteroids, or if you're being more cynical, it was designed to distribute tax dollars to as many districts as possible.
> Is it because, for whatever reason, we didn't get the Exploration Upper Stage done?
Reaching NRHO actually requires the Exploration Upper Stage, which is still happening.
>Let’s assume that we had kept flying with the systems we had at the time, that we had continued to execute two manned Apollo lunar missions every year, as was done in 1971-72. This would have cost about $4.8 billion annually in Fiscal 2000 dollars.
>Further, let us assume that we had established a continuing program of space station activities in Earth orbit, built on the Apollo CSM, Saturn I-B, and Skylab systems. Four crew rotation launches per year, plus a new Skylab cluster every five years to augment or replace existing modules, would have cost about $1.5 billion/year. This entire program of six manned flights per year, two of them to the Moon, would have cost about $6.3 billion annually in Fiscal 2000 dollars. The average annual NASA budget in the 15 difficult years from 1974-88 was $10.5 billion; with 60% of it allocated to human spaceflight, there would have been sufficient funding to continue a stable program of lunar exploration as well as the development of Earth orbital infrastructure. I suggest that this would have been a better strategic alternative than the choices that were in fact made, almost 40 years ago.
Elon Musk will be looked back on by history as one of our great heroes like Thomas Edison for his work bringing electric cars into the mainstream, improving electronic payments, bringing back free speech, building a global inexpensive Internet network, and rekindling man's interest in space.
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[ 7.1 ms ] story [ 271 ms ] threadFor a critique of the current method, I found the SmarterEveryDay lecture on it gave some good food for thought!
The SmarterEverDay concerns about the orbit seemed to be that while landing or taking off maneuvers were short & low energy (good), it meant the opportunity only came about every couple days (bad).
SED also stressed that Artemis is relying on crulyonic fuel transfer. SED repeatedly pointed out this is a tech that has never been tested, ever.
https://www.youtube.com/watch?v=OoJsPvmFixU
The other thing he mentioned was the Apollo success playbook (SP-287), "What Made Apollo a Success?"
https://ntrs.nasa.gov/api/citations/19720005243/downloads/19...
Link to EPUB version https://old.reddit.com/r/SmarterEveryDay/comments/18aw4ca/i_...
At it's peak, the Apollo project was funded to the tune of 1.1% total US federal outlays during the time period it ran. That's an enormous amount of money, which failed to produce a remotely sustainable result. You got what you got: moon landings done quick, and then never again.
The modern Apollo project is SLS which...is a big, expensive, absolutely cannot fail rocket (which is really a jobs program for preferred contractor districts, with technology choices decided by politicians not engineers).
Basically the SED lecture spends a lot of time gesturing at Apollo, but never addresses the actual problem which is NASA is funded the way it's funded: of course they know they're going to miss their launch dates, they're not funded to hit them, and they're probably going to wind up redesigning the mission once Starship is flying to orbit and actual performance numbers are realized off-paper. The SLS is the SLS for the same reason: at the time the program started there was no SpaceX, nor Space Shuttle and it was something of a national embarrassment the US didn't have a manned space capability but the Russians still did.
In short, for a lecture which opens talking about people worrying about disagreeing with their superiors, he stays well away from the actual live-wires of the issues.
If they can really get Starship and orbital refueling working, it's a step function forward.
There were already programs like NERVA in development for an advanced nuclear upper stage. Once you have that, making the Upper Stage refuel-able, makes it basically into a multi-use space tug for cis-lunar.
Then you could evolve Saturn 1B into a reusable Saturn 1C, just like Falcon 9. That gives you a reusable heavy lifter. And it would also safe a gigantic amount of money that was spend on Atlas/Titan/Delta in the next 40 years.
The Apollo capsule was not reusable but continuously evolving a capsule design in that direct was certainty possible. But its not the most important part of the system in terms of cost.
What really need more development is the lander itself. Making a large reusable lander would have been costly but not really out of reach.
You can use an occasional Saturn V for large things like Skylab and special deep space mission.
That was a much better path forward then Space Shuttle and ISS.
"The Apollo lunar base proposal saw an uncrewed Saturn V used to land a shelter based on the Apollo Command/Service Module (CSM) on the Moon." <https://en.wikipedia.org/wiki/Apollo_Applications_Program#AE...>
Aerodynamic drag is amazing. It means fins and parachutes work. It means you can slow yourself down without propellant and with passive systems.
Mars actually kind of sucks too because it has just enough atmosphere to interfere with rocket engine ignition but not enough to be able to land on chutes alone. But any amount of parachute and aerobraking is better then none.
But the Moon is terrible: no atmosphere, so you're under engine power the whole way down. The propellant and mass demands are thus much higher.
1. http://www.astronautix.com/a/apollolmshelter.html
And I think what that kind of analysis misses is how many important multi-use technologies are developed. Starship will mostly not be used for moon, but financed with moon money.
It is definitely possible if the fixed cost(e.g. R and D, manufacturing capability, testing infrastructure etc) is majority of the cost and scaling up doesn't increase them linearly. Cost of raw materials like fuel or building material would be negligible for Apollo or SLS in comparison.
Because this will be the first time in history that the cost of a launch will be mostly the cost of the fuel. This is the first fully reusable rocket in history. If you had to throw away a dozen tankers it wouldn’t make any sense.
Water, food, air, parts, habitats, ..etc. All of that adds up. Super Heavy lift capability and refueling will be vital to making those plans feasible.
I have no idea if that's just Elon spouting nonsense or if it's realistic, but that seems to be the goal.
It makes the notion of ss cans supporting Mars colonization a bad joke. The cans might be just barely adequate to support a Lunar outpost. The "gateway" concept is another bad joke. It is in plans solely because that is the closest to the moon that SLS can get to. It isn't legitimately a gateway to anything: stopping there makes getting where you really want to go substantially harder. The only legitimate place for a gateway would be in high Earth orbit, because it wouldn't require extra fuel to stop at it and then get moving again.
SpaceX is already launching 100 times a year. Starship is supposed to have even faster turn around, launching multiple 100 times per year doesn't seem crazy, specially as current launches require complex iteration, unlike pure fuel launches. Its likely closer to 16 then 20. And optimizing the process and efficiency it will be less then that.
You end up landing around 100 tons. So you can potentially do 1000+ tons a year, and that is before you even go to having many ocean launch pads.
Ok not enough for colonization, but its a damn good start.
The "Mars colonization" story is purely to pump up stock price, just like the "full self driving" that was supposed to enable you to farm out your car during the day for taxi service. Musk hyped that one hard.
Landing a single Starship on Mars literally is already an output if we want to be exact about it.
The idea that the Starship architecture isn't enough to have a small base on Mars is just nonsense.
> The story about ferrying 100 people to Mars in a can is 100% lying; they might fit a dozen.
As with everything 100 was an inspirational goal, once you have good infrastructure on both sides and everything optimized for mass transport. And yes you might be right, 100 is to optimistic. He didn't sign any contracts based on those numbers, he promised nobody that number. Its literally an inspirational goal with a low chance of success.
> they might fit a dozen
Damn, a dozen is amazing.
> And there is literally nothing on Mars worth refining and exporting home
Nobody claimed their was ... but you are really good a fighting straw man.
> "Mars colonization" story is purely to pump up stock price
That just proves that you don't have the first clue what you are talking about. Musk literally admits that Mars colonization isn't gone make money. The reason they want Starlink is because they think that can actually make money and support large rockets so they can use it for Mars. Musk things he will spend his private money on Mars colonization. Pushing Mars is literally the opposite of stock price pumping.
He also knows there can be no colony. So, every falsehood promoting it is a lie.
100 people would mean about 10m3 per person. That sounds like more then some prisoners have had in isolation cells. Of course wouldn't be comfortable necessary, and in practice you likely wouldn't do that way.
Of course this talks about a situation where there is lots of infrastructure on both sides. No need to bring extra food or equipment. A pure crew ship. Near perfect system of water reuse and so on.It also presupposes some understanding of solar radiation or much better cancer treatment.
In addition you can think of a number of ways to expand volume.You can potentially stretch the ship, or widen the ship. You could have inflatable hubs to temporary create extra volume. The earlier version of the ship when that 100 number was first talked about was also much bigger then the current one, the ship designed has changed because they realized lower cost per stack and higher re-usability made more sense. Maybe it would require medically induce sleep (bear style).
100 is of course inspirational and might be off by a factor of 2-4x but to act like this statements are some unforgivable lie is ridiculous. Specially because there is are no contracts signed or promises made, its literally just 'this is our long term goal'. Complaining because a ship can 'only' transport 12 people to FUCKING MARS is just insane to me.
And in the end the cost per person is what actually matters, and that is what they are trying to reduce systematically. If you actually listen to Elon that's what he talks about most and what has always been the main driving goal. He talks far more about that in the interviews about this, the actual number he threw out are just estimation, and he makes that very clear. He even makes it clear that they don't know how to get there yet, they literally just working towards it as best as they can. 100 per ship is just one of many estimated numbers. A million people to self sufficiency. 1000 ships operational. Many others. All those numbers might be very wrong and Elon would admit as much. Its not the 'gatcha' you think it is.
And notice how you didn't defend your ridiculous 'pump-and-dump' nonsense.
Nobody mentioned "dumping". Please do not make things up.
The problem of "we need to get off the moon now" is "okay, but where are you going and what's going to be there that's more useful then where you are?"
It's not unreasonable to note that a medical emergency would be much better dealt with on the moon - where you have gravity - then in orbit, where you don't. Whereas if you need to bail out and get to Earth fast (which you can't) then you'd be better off just dropping a vehicle which can do that onto the surface.
Test flights are a very different beast. Early tests can be expected to fail; some are supposed to fail ("destructive testing"). Explosions and other failures become much more concerning later in the process; for example, Boeing's Starliner's latest test flight was supposed to demonstrate everything was working correctly. It failed to do so.
In the two Starship launches so far, SpaceX was very clear with expectations in advance. Each likely has dozens of objectives. The second flight very clearly accomplished more than the first; a successful test of the launchpad mitigations, a successful test of all first-stage engines staying lit, a successful test of separation, a successful test of the second-stage engines all lighting, etc.
But now an explosion is an expected outcome for your million dollar hardware.
That approach works in software dev.
A test starship is nowhere near that, though we don't have exact numbers. Probably closer to $100 million.
Also SpaceX is trying to solve a much harder problem. If you would have asked that Saturn team "Also, land all the stages of the rocket", the likely answer you would have got is "Screw off, you're insane" or "Give me 100 billion dollars".
The fuck? NASA lost people in production hardware multiple times.
https://en.wikipedia.org/wiki/Apollo_1
https://en.wikipedia.org/wiki/Apollo_6 "The damaged third-stage engine failed to restart for trans-lunar injection... Despite the engine failures, the flight provided NASA with enough confidence to use the Saturn V for crewed launches..."
https://en.wikipedia.org/wiki/Apollo_13
https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disas...
https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste...
Here's a fun one: They tested the Saturn crew escape system. The booster was supposed to blow up, and demonstrate the crew would survive... but the test went wrong, and it blew up early, when it shouldn't have. The crew abort worked, so test failed successfully.
https://www.youtube.com/watch?v=AqeJzItldSQ
> Apollo 1, initially designated AS-204, was planned to be the first crewed mission of the Apollo program.
https://en.m.wikipedia.org/wiki/Apollo_1
The "accidental abort test" was launched on a Little Joe II, a simple single-stage solid rocket motor, not a Saturn of any variety. This booster was unrelated to any Saturn hardware.
If the Starship second stage failed to restart causing it to fail to get to TLI, or tried to take out its manned crew like 13 did, you’d be claiming it’s still a sterling safety record?
You’d have considered this test a success if it reached orbit “despite sustaining severe damage” on the way up?
Come on.
> Every crewed launch of the Saturn V was a success
Fine. Same for Starship, so far.
“My hunch is that whatever happens, we'll see scenes of Apollo people clapping and cheering and Apollo fans calling the flight a success. From what they tell me, no Apollo launch has ever failed.”
b) The Apollo program actually cost not just money, but human lives = a much worse outcome than just losing a test rocket. And Apollo 13 crew was very lucky to have returned to Earth alive.
c) Losses of test hardware can only really be somewhat prevented by being extremely careful and pedantic during development, which takes time, and guess what? More time spent obsessing about every single detail = more money spent on development. It is entirely possible that the "hardware is expendable" approach is much cheaper than what you would like to have.
Demonstrably incorrect.
Examples:
https://www.youtube.com/watch?v=AqeJzItldSQ is a Saturn launch abort test that failed. It failed in a way that they were able to determine that intended test would have worked, though. 1:20 for the meat of things.
https://en.wikipedia.org/wiki/Apollo_6 also failed to achieve its objectives; "Despite the engine failures, the flight provided NASA with enough confidence to use the Saturn V for crewed launches; a potential third uncrewed flight was cancelled."
All that aside, SpaceX was quite clear that the latest Starship test had multiple objectives, and that "successfully splashdown near Hawaii" was deemed quite unlikely. It successfully demonstrated a number of items, including fairly critically the launchpad changes. It wasn't one test; it was a bunch of tests in one flight.
If that last category doesn't succeed that doesn't mean the test flight was a "failure" from the businesses perspective. They still got what they wanted, they just didn't get the icing on top.
The test flight that destroyed the pad is properly categorized as a failure. The flight termination system was expected to work. They expected not to cause that much damage to their infrastructure and surroundings, their relationship with the FAA, their ability to get licenses, etc. To argue that it wasn't a failure, you have to argue that the flight termination system was in the category of systems where a failure was considered acceptable. If that was the case, everyone involved in launching that flight ought to to go jail for recklessly endangering the public.
The most recent test flight though seems to have been a pretty resounding success. Everything that they said they really wanted to see happen, happened. Yes, both stages had failures in "we might not even get here" test objectives after that. That's ok.
The success criteria for integrated launch test 1 was to clear the launch pad (which it nearly destroyed) test 2 was get past the stage seperation, which it did.
Spacex have a very fast cadence for tests and seem not to make the same error twice. The best test environment is really trying to fly the ship.
Launch one really was a comedy of errors in the launch platform.
In launch 2 the booster did exactly what every other booster by everyone else (except the falcon 9) does. Got it's payload to the target altitude before separation.
The second stage reached space.
The N1 platform didn't do any of that.
You have no idea what a testing platform looks like, and are too used to NASA one shot rockets that cost 3 billion each just to make sure nothing goes wrong.
The second stage exploded as well, possibly because of FTS, possibly not (was it ever confirmed?).
It exploded while attempting to test its landing maneuver. If it just turned off the engines and dropped itself into the ocean like a normal booster, it likely would not have exploded (for one thing, there wouldn't be any fuel left in it being saved for landing).
SpaceX clearly has a winning method, as they have a success rate of 99.3% and hold the record for most consecutive successful launches at 253. Second place is Soyuz-U, which had 112 consecutive successful launches and an overall success rate of 97.3%. SpaceX has more consecutive successful booster landings (173) than any space program has had successful launches.
A few people have slosh modeled the booster flip around duplicating observed speeds and accelerations and surmise the following. The flip around was too rapid causing slosh to one size of the booster. In addition there was negative acceleration that would have allowed the remaining fuel to experience zero gees pulling it away from the bottom of the rocket. When the engines fired back up it would have hit the bottom of the rocket with something between 20 and 100 tons of force. Based on SpaceX description, the FTS was not used.
The second stage at least appears to be oxygen leakage. The graphs shown on flight day started showing a more rapid depletion of oxygen after second stage lighting. SpaceXs language was something like 'flight was unable to reach orbital insertion and was terminated, pointing to the FTS being used.
This sounds wasteful on paper, but in practice it is much much faster and amazingly enough cheaper. With traditional rockets you never make enough to enjoy economies of scale, but with SpaceX's approach they've dropped the cost of the engine by about an order of magnitude over just a few years, and it was already a very inexpensive engine. For the cost of a single RS-25 you can buy 400 Raptors.
Multiple iterations of test flights that are expected to fail is a much faster way to develop impressive tech than spending 3x longer doing on the ground analysis of every detail of everything because you can't bear the PR hit of something that can be painted as a failure.
The refueling team might be ready to test, even though the "don't explode" team are still working on it.
There are some great documentaries about the NASA team that does safety critical software: https://www.youtube.com/watch?v=iJNNJxC12UM
Before that last flight it seemed like engine reliability wouldn't get solved. But now they have a clear path to orbit.
I doubt the heat shields will hold up on the first several re-entry attempts but there's been recent sightings of a new heat shield that has tiles about half the size. Maybe smaller tiles will have less lever action and will have 4x the fasteners.
This is still the number one problem with Starship. There were all these wild claims of an exotic new liquid cooled reentry system at the beginning. But because physics they ended up going right back to using ablative. They'll suffer the same fate as the shuttle for it. Nothing has fundamentally changed in ceramic or adhesive technology since then, and the lack of aerodynamic control means they will have to survive even steeper descents with greater thermal load. I imagine the idea of Starship as an earth return vehicle in general will probably be abandoned, so they can optimize it for interplanetary transport and lunar operations.
> the lack of aerodynamic control
There are literally wings on the ship.
https://en.wikipedia.org/wiki/Siberian_flying_squirrel
Yes, it is. There is no such thing as a non-ablative reentry vehicle. The tiles are effectively no different than what was used on the shuttle.
>There are literally wings on the ship.
Starship has no meaningful aerodynamic control beyond what is required to perform the flip. It has no ailerons or elevators. It falls to the earth in a completely ballistic trajectory.
[1] https://en.wikipedia.org/wiki/Heat_shield#Spacecraft
Thermal soak heat protection: the protective material absorbs - soaks - the heat, becomes really hot, and after the process need to dissipate the heat. Also - which is important - the heat capacity of the material should be enough to absorb the whole heat flux going into it. Also - thermal conductivity of this protection should be such that the protected material behind it won't get too much heat. For this kind of protection to work you want small temperature differentials - less heat flux - and small time of heating - otherwise the material will become too hot. However - as materials have varying thermal conductivity - the thermal soak is always present to some degree.
Radiative protection: the protective material heats up so much it stops accepting more heat, because it radiates heat back with the same speed. After the process the surface of this material is really hot. Important requirement - low thermal conductivity, as the high temperature on the surface shouldn't get behind the protective layer. Also known as refractory protection. Space Shuttle thermal protection is an example.
Ablative protection: the surface of the protective material releases its material in the form of gases, and this gasification process cools down the material. The material gets consumed, that's the main problem with this cooling approach - neither big thermal capacity nor small thermal conductivity are needed. Early Merlin engines used ablative cooling.
According to Wikipedia, SpaceX uses ablative protection for Crew Dragon - https://en.wikipedia.org/wiki/Atmospheric_entry#Thermal_prot... -
"A second enhanced version of PICA—called PICA-3—was developed by SpaceX during the mid-2010s. It was first flight tested on the Crew Dragon spacecraft in 2019 during the flight demonstration mission, in April 2019, and put into regular service on that spacecraft in 2020." .
Also from Wikipedia, tiles of Starship are made of silica - https://en.wikipedia.org/wiki/Starship_rocket#Starship_space... -
"Starship's heat shield, composed of eighteen thousand[131][132] hexagonal black tiles that can withstand temperatures of 1,400 °C (2,600 °F),[133][134] is designed to protect the vehicle during atmospheric entry and be used multiple times with minimal maintenance between flights.[135] The tiles are made of silica[136] and are attached with pins rather than glued,[134] with small gaps in between to allow for heat expansion.[2]"
which makes them a kind of radiative or refractory protection.
They are effectively ablative in the sense that neither vehicle has (or will) be able to complete successive missions without massive replacement of damaged and missing tiles. The fundamental approach is not suitable to reusability, as we learned with the shuttle.
The Dragon Capsule for example has an Ablative Heat-Shield. But that doesn't necessarily mean it can't do multiple missions in a row. It just depends on how the shield is designed. The Dragon could potentially do many earth missions without replacing the heat shield.
Second, you are wrong in that there is anything fundamental about Starship or Shuttle heat shield not being able to fly multiple missions. If the tiles are still attached and not damaged, then all that has to happen is for the tiles to cool down. After that they are ready for another flight, meaning the tiles are not ablative.
Now experience on Shuttle has shown that if you are not careful tiles could fall of or be damaged. Damage can be reduced in various was and Starship without an external tank is already much better by design.
Additionally Shuttle had to glue tiles to a fragile aluminum frame making the installation very hard and the tiles very fragile. Starship on the other hand uses welded studs on a steel frame. So even if a tile is lots, the steel should still hold up pretty well. In on case Shuttle was saved because there just so happened to be steel under a damaged tile.
So you are right, heat shield is one of the biggest issue that could cause problems with rapid reputability. You are wrong, the tiles are not ablative cooled. But Starship tiles are totally different then Shuttles, they have made many improvements in the heat shield and its construction and in the heat shield tiles themselves.
Starship can likely survive even with a number of missing tiles if required. In some position tile lose can certainty be fatal.
Starship will need several launches of methane+oxygen to travel beyond LEO. That model requires a reusable orbital tanker to make sense economically.
I honestly don't understand this whole post chain. The booster needs to survive because it is the most valuable part of the rocket and yet we are supposed to praise it for exploding? The hot staging concept isn't viable over the long term because it goes counter to the goals of reusability.
I don't need people to rewrite history by claiming that if the booster of the SLS exploded, it would be considered a success since nobody intends to reuse it. Yeah, that is how you get a two billion dollar launch tag. You can't convince congress to drop the SLS if you keep losing boosters.
I wouldn't praise the booster for exploding, but I would praise the engineers for getting it all the way to staging without engine failures. That's all most boosters are expected to do.
SLS isn't expected to explode because it's based on space shuttle parts that stopped exploding decades ago.
Its not that wild. That technology is likely used on certain military equipment.
I was certainty something not tested at that scale but it wasn't a crazy thing to think about.
> But because physics they ended up going right back to using ablative.
They are not ablative.
> Nothing has fundamentally changed in ceramic or
What's your evidence? Have you done lots of study on Space Heat shield? Please share your findings.
> adhesive technology since then
That just wrong. Starship uses mostly welded studs steel frame. Totally different from Shuttle.
> and the lack of aerodynamic control
They have sufficient aerodynamic control. What evidence do you have that they don't? They have shown simulation of this before. I'm gone go with SpaceX on this unless you show me some simulation that shows insufficient control.
building the header tanks in the first place, and testing them is the interation style. If the starship blows up, the header tanks are the least of your worries.
Are you referring to Starhopper? It is still present at Starbase as of recently.
https://www.google.com/maps/place/Starhopper/@25.9977631,-97...
And "time is money" - if you want to develop $ComplexTech fast, then you should start doing R&D work as soon as physically possible.
The “payload” is an experiment that is at most two tanks, a valve and monitoring equipment. However it is pretty clear they will use the existing LOX main and header tanks and valves already present in every Starship. This will meet the requirements of NASA’s 2020 $53 million challenge to “transfer 10 metric tons of cryogenic propellant, specifically liquid oxygen, between tanks on a Starship vehicle”[1] as the smaller header tank holds roughly 20 tons.
If you are already attempting to get into orbit it makes sense to include this experiment in case you succeed because you save the time and cost of an entire launch and might get a $53 million award while advancing a key requirement for HLS, a $2.9 billion dollar contract and the current core mission.
This experiment has been planned for years, Starship was designed to do it and it makes sense to do it now. SpaceX clearly knows what they are doing. Unfortunately HN is terrible on this subject.
[1] https://www.nasa.gov/technology/2020-nasa-tipping-point-sele...
The big issue is that unlike all fuel that has been moved between tanks in microgravity in the past, SpaceX isn't storing their fuel in a flexible tank. Instead, they have the fuel and the pressurant gas in the same tank. Under acceleration (gravity or otherwise), this is not a problem, because the fuel pools naturally "down", with the pressurant above it.
However, as soon as the acceleration stops, there is no more down. Instead of having a bunch of fuel on the bottom and pressurant above, the tank will contain a chaotic mixture of floating gas and liquid.
The minimum setup for fuel transfer is a maneuvering system capable of a very long, weak impulse (to provide down), and then some kind of pump that moves fuel, because the force provided by the weak impulse of a maneuvering thruster is not enough to do it on it's own.
The idea of circulating a mixture & taking one you need is for example how donating blood plasma platelets works. If we can separate fuel and pressurant without too much fuss, a similar non-propulsive technique for a cryonic fill might be possible?
I'm not sure I understand how your pump idea works though.
Putting propellers on electric motors inside the tanks, to make fluid circulate axially around the center line, would propel it to intakes on the circumference, with a growing bubble running down the center. Then they would not need to accelerate the vehicle throughout the process, which alternative seems wholly impractical.
It would require clever design of the anti-slosh baffles (never shown in cutaway diagrams) to be compatible with such circulation. It might be tricky to keep the whole tank from switching to tumbling end-over-end.
"But wait, it's supposed to be more complicated than that!" No, really, they've been doing this stuff for years, and settling propellant for upper stage coasts really is virtually the same thing as settling for propellant transfer (transferring to the engine(s) for relight vs transferring to another stage... in fact you have to be MORE careful to avoid bubbles when feeding propellant to an engine than you do when transferring propellant to another tank). https://www.youtube.com/watch?v=mVAGoWJuDKk
They still need to do the whole launch-two-starships-then-dock-them bit, plus quick connect fittings, but they already have years of experience with autonomous rendezvous and docking from operating Dragon at ISS (Dragon 2 has that capability, and it has been used for the uncrewed Dragon 2 demo mission plus the recent cargo Dragon 2 missions, plus I think it's the nominal choice even for crewed missions).
In principle you could apply acceleration for a while in one direction; and then switch to accelerating in the other direction, wait for the fluid to settle at the other end, and pump from that end, alternating back and forth. But it still consumes reaction mass, and introduces delays while switching.
Docking vehicles massing hundreds of tons is a much bigger problem than docking Dragon. The Dragon experience might not apply very directly.
Presumably the engineers actually involved all understand this (literally rocket science) much better than we do.
Docking dragon is obviously similar to docking starships (Dragon berthing sensors were tested on Shuttle, broadly similar to an empty Starship). You’re right, tho, that the actual SpaceX engineers (who proposed this and developed Dragon) understand this better than random online folk.
Great attention to detail, very scientific movie.
The traditional solution is to replace acceleration/gravity with surface tension, using various types of Propellant Management Devices (PMDs).[0][1]
When last we saw our heroes, the stated plan was to solve the problem with milli-g acceleration via small thrusters.[2] That was 2017, but so far there's been no indication this part of the plan has changed.
[0] https://en.wikipedia.org/wiki/Propellant_management_device
[1] https://www.google.com/search?q=Propellant+management+device...
[2] https://youtu.be/S5V7R_se1Xc?t=2872
Literally KSP career mode IRL
The ship is the payload. The testing is inside of the tanks of the ship. Moving fuel around inside the ship. There is no extra expensive payload in addition to the ship.
Keep in mind that the RS-25's cost $100m each. If it was atlas, the engines alone would cost $3.6B.
Edit: propellant is relatively cheap I believe. My understanding is <$1m per launch.
$44m per booster starts to sound like a more reasonable number.
I suppose that’s par for the course when bringing a previously lab-bound type of engine into practical use, but still. Did Merlin see iteration at such a pace prior to being fitted on Falcon 9’s? Raptor looks to be on track to be in a considerably more refined state when Starship goes into service than Merlin was at during the same point with Falcons.
But what you get at the end with something like 3000 parts in it's BOM, to something like 20 parts in the BOM, because most of the parts were deleted and integrated directly into the mold.
I suppose the better way to put it might be that Merlin's iteration was more in getting the production sorted out, whereas Raptor is iterating everything based on lessons from Merlin and previous Raptor iterations.
From what I understand, the engines are still >$1m each, but coming down as they ramp up production speed and have radically simplified the engines with V2. The body is probably also much higher than the target range, but bearing in mind that it's just stainless steel and relatively well known manufacturing techniques, and not aluminium going through complex and expensive manufacturing techniques, they're probably well under any other typical rocket. I'd assume even significantly less than a new Falcon 9, which is already the low end of the industry in terms of price.
Another thing I'd bear in mind is that many of these ships never got completed, on purpose. There have been explicit "pathfinder" builds, but even with the "real" ships most never flew and were pretty much about working through techniques, tools, materials, etc. These won't have needed a full fit-out and will have been cheaper.
Edit: updated engine target from 500k to 250k
SpaceX has built and scrapped 17 Starships, 14 of them without even a static fire. They have scrapped four Super Heavy boosters, three of them without firing.
Test flights require fuel, planning, approval, and of course flight hardware. None of that is free.
I think the issue you seem to be missing is that the marginal cost of materials that go into building a rocket is very low. The fuel cost is similarly a small percentage of the cost of building a rocket. The cost comes from the large workforce required and the low flight rate.
About the same as every rocket that has ever been launched in all of history.
i.e. even when they are successful, every rocket in history before SpaceX's Falcon 9 "loses" the lower stage.
For example, there is speculation that a finless "Starship" that had been seen at the site some time ago which now appears to be being scrapped without any use was thrown together in case S25 was not ready in time for the second flight. So while construction wise they spent money, is that money that was part of the test cost?
Similarly, they're moving to Starship V2 and Raptors are moving to V3, making the previous hardware obsolete. But since they can still gather data from launching the older hardware, they will launch and lose it since scrapping is supposed to happen anyway. So at that point losing the vehicle in flight hasn't cost them much more than just scrapping it.
However, since you probably mean actual construction cost, the boosters must clearly be expensive, thus their interest in getting those working even if it means sticking sacrificial Starships on top.
I'd guess each unit is probably around $40-50 million each. Still revolutionarily cheap per kg, but certainly not so cheap that they can keep endlessly throwing them away on incremental steps.
It was depressing until I realized: SpaceX is absolutely carrying that spirit.
Remember when all the experts said it was impossible to ever land their first stage? And then that it was impossible to ever make that economical? And then remember when Elon teased Starship (back then it was called BFR) and all the naysaying that went along with that?
They've just kept going. Just an absolutely break-neck pace. Falcon heavy was barely supposed to even work, and now it's not even news when they launch one.
edit: ha! I think there's actually a falcon heavy launch tonight!
This one is yet to be determined, isn't it?
But it would seem pretty foolish for SpaceX to be continually reusing rockets this much if that cost them extra money?
(I mean extra vs building new ones)
SpaceX sold launches at around 60-70 million $ and that made it profitable. Once the proved out reuse, they were able to get investors. My contention is that unless they could actually show reuse they could have never raised they amount of money they did, it wouldn't make sense.
Another way of thinking about it is, what based on basic principles is the cost of building these things. Various people have estimated this stuff. 20-30 million $ for the first stage with engines, 5-15 million $ for the second stage, 6 million $. Probably 20-30% overhead for operations and fixed cost.
Now things are different. The first stages are going on 20 reuses. The second stage is now being mass produced pretty significant volume, so price goes. Fairing are reused also. You have the same size operations team that is far more efficient. A team that used to do 10 launch now does 50 launches. Moving to automated range safety is one big such optimization. The launch pad utilization is far higher.
So most people who look at this come out for with a marginal cost of about 15-20 million $ per launch. You can be conservative and say 30 million but it hard to come up with reason why it should be so high. At the same time they are still selling launches at 65 million. And in addition to that, they have many special launches that are likely earn them more, DoD launches, NASA launches, Crew launches and Falcon Heavy launches.
So I think it really, really hard to argue that SpaceX core business isn't very profitable. You would basically have to claim that first stages get totally rebuilt from the ground up and all engines replaced. But we have very good evidence that this isn't the case.
Now of course that doesn't mean SpaceX is profitable, as thanks to the re-usability success, they invested heavily in Starship and Starlink. And those are of course unprofitable investments for now. Starlink is starting to turn around, but Starship is quite a bit away from that.
What can maybe be argued is that if you only had say 10 launches a year, re-usability wouldn't be worth it for various reason.
Yeah, for SpaceX, experimental hardware is expendable. Yeah, it is not very typical in space industry. But it is a tried-and-tested approach, which gave them the Falcon 9, the most reliable and technologically advanced launcher of today.
The falcon 9 succeed on it's first launch, it was not a test flight heavy program.
The falcon 1, SpaceX's only orbital rocket prior to the falcon 9, did fail on it's first three flights, however it was never intended to and that nearly bankrupt the company. They destroyed third party payloads on flights 1 and 3, because these were intended to work, not be test flights.
Long after it was in production the falcon 9 did begin a "test-flight" heavy program, but that was for developing the ability to recover boosters after they had successfully delivered a customer payload in an operational flight, not for developing the rocket itself.
The series of failures when attempting to land for the first time was spectacular.
Suppose that the eventual production vehicle has a fairly different design, a different name, and it succeeds on its first flight. Would it then have used the same methodology that resulted in Falcon 9?
I'm only asking rhetorically. The Ship of Theseus is an interesting philosophical question, but the way you define "methodology" shouldn't depend on your answer.
I've been seeing parallels to this growing at an odd rate. Where context is removed and HN only cares about results at TRL ~7.5+. Its often quite baffling to see systems/models designed in academic spaces with minimal compute resources to systems/models with billions of parameters and millions of dollars in funding. Or to see TRL 2/3 projects be dismissed because they are not >TRL 6. I wonder how people that make these types of responses think research and development happens if you must catapult one's self from a theory to usable product in a realistic environment before it becomes of any interest. It seems rather anti-scientific tbh. Not what I'd really expect from a crowd dominated by developers, engineers, researchers, and scientists.
As for rockets, well... exploding rockets are expected during testing phases. Obviously you want to reduce this, but catastrophic failures, or any failure, serve as great learning opportunities due to the inability to formulate a complete model (combustion instability is a notoriously difficult problem).
I think also many are interested in the subject and so do watch videos and read other sources but that these are at high level discussions and often not getting into the low level nuance that is actually necessary for solving these types of problems. But that as humans we often conflate excitement and time with a subject with expertise in that subject (all time is not equal). Personally I wonder if this is an accurate and general phenomena and exacerbated by our growing information age combined with the large number of armchair science communicators. I think all nerds, including myself, have been guilty of asserting things as facts (or with stronger confidence than they should be), often in an effort to help inform others or simply wishing to participate.
On a side note: anyone feel like it's a bit weird how low (aerospace) engineers are paid in comparison to us in software? Like not bad wages overall but there is a large gap (not looking to get my pay decreased, but the other way around)
Blue Origin: 85k/119k/162k (bottom 10%/Median/Top 10%)(https://spacecrew.com/salaries/blue-origin-salary)
SpaceX: 69k/112k/178k (https://spacecrew.com/salaries/spacex-salary)
Software produces gobs of money, the likes of which the world has never seen. Aerospace as an industry may not ever be profitable. It's as easy as that.
I definitely agree that software is more profitable, but the gap is a bit surprising, especially considering the high skills and training required.
But while writing this I decided to check instead of making what I thought was a reasonable assumption. Apparently the net worth of the CEOs of Boeing, Lockheed, and Raytheon are under $100m? That's a bit surprising if the numbers I googled are accurate. That would make the net worth of the two primary shareholders of BMW 1000x their counterparts. Each! I scrolled through Forbes billionaires and I didn't find aerospace anywhere but I did find pig breeding, shipping, and Chick-fil-A, candy, soy sauce, videogames, legos, in-n-out, dental implants, "Star Wars", "Billboards", and even "drones". Especially considering that there's a lot of shipping on there and a drone billionaire.
Really makes me think some of the other things are over priced tbh. Especially with how many crypto-bros are on that list.
Edit: Wait! "762 Charles Edelstenne" is listed as "aviation" but he cofounded Dassault...
Edit 2: "868 Neal Blue & family" is listed as "Defense" for General Atomics and "871 Eren Ozmen" as "Aerospace" for Sierra Nevada. "916 Fatih Ozmen" also for Sierra Nevada. So okay, maybe some are on this list but my intuition suggested defense and aerospace would have at least someone in the top 100. Surprised not even the top 500.
All of them under $4bn btw
Having to compete with the likes of Airbus and ULA for workers, SpaceX doesn't need to inflate the salaries that much to get top talents.
https://www.nasa.gov/directorates/somd/space-communications-...
Looking at the Western space industry history, Starship development is only comparable to the Apollo or the Space Shuttle program - both of which would be insanely expensive in 2023 dollars, certainly exceeding 100 billion USD each, perhaps 300 billion USD in case of Apollo.
I don't think there is any chance of SpaceX going bankrupt, even ignoring how easy it is for them to raise capital.
The whole idea that some sort of better type humans will travel to another planet is frankly ridiculous. We don't learn from our own mistakes - see WW1, WW2, current state of affairs. If anything, we would most likely destroy Mars and Moon much faster than how we wronged Planet Earth.
I have no idea where did you get this from :) .
Why are you thinking that's the intention?
(We should probably start with the moon, though)
An off planet colony would likely face the same issues of sustainability as soon as different factions start competing for resources.
The path to making colonies on Mars or the moon self sustaining is not even clear at this point. Starting with the simplest of fundamentals - air, water, food and protection from cosmic radiation. The prospect of growing a technical civilisation on either body, that can develop further without support from Earth is remote.
By contrast, to make earth unlivable basically means nuclear war. Climate change won't do it, biological pandemics won't do it, nor will fossil fuel exhaustion or any other localised event.
On the worst day possible on earth (global radiation aside) its still a million times better to live on than anywhere else.
In terms of global radiation making the world uninhabitable even then tiny, non-sustaining pockets of humanity would survive. At least until their life-support systems failed.
Lastly, I wonder at the need for "the future of mankind" as a goal at all.
That said, ‘colonizing’ the artic or shallow ocean floor probably accomplishes most of the benefit for a subset of the cost and risk.
The only real benefit I see to space over the attic is that off worlding mining and production could be a benefit in itself.
If all the water on mars were melted, it would cover the planet in 100ft of water [1]. With the safe assumption of any kind of water recycling, and indoor habitats, there's plenty of water on mars, which also means there's plenty of oxygen on mars (along with the 95% CO2). The atmosphere is 3% nitrogen, and 1.6% argon, which means there's plenty of air on mars. You don't have to fill the sky with air, just the buildings.
[1] https://marsed.asu.edu/mep/water#:~:text=Taking%20what%20can....)
Also the argument taken to an extreme is straightforward. We know that massive catastrophes have caused mass extinctions that wiped out most life on Earth. This is clearly visible in the fossil record. Ergo, one of these is certain to happen again. In the extremely long term, the Sun will get hot enough to kill all life on Earth in a couple hundred million years. So Humankind is doomed if we do stay on just Earth for the very long term.
There's also the side argument that "right now" appears very close to making it possible. If Starship and the attempt at reusable rockets were to disappear there's nothing guaranteeing the progress of space technology. It's easy to see a future where we do some more footprints on the Moon and maybe later some footprints on Mars, but no permanent off-earth colony is ever established. Eventually we give up on creating such bases because they're deemed too expensive and "robots do it better" as our robotic technology gets better and better. The technology of how to do reusable vehicles is eventually forgotten over several generations and then we never leave Earth again. (Eventually resulting in our destruction.) This is a "why not now?" argument.
That bypasses the whole "refueling" problem.
A large part of the propellant is used by the time the tank is up in space. The plan is to transfer the remaining (10%?) of fuel.
Also would probably be just about as hard to swap tanks.
It’s a longer episode but well worth the watch if you enjoy the channel and are excited about returning to the moon.
https://youtu.be/OoJsPvmFixU?si=qcg_BX2GeZm4u1GG
I think this kind of misses the point of the video, which was not about the technology of Apollo as much as it was the design principles that went into making the mission a success. Technology obviously is involved in that, but the argument for "do it like Apollo" is more a long form version of "keep it simple, stupid".
A good example of this is when Destin brought up the Apollo 1 capsule fire[1] which changed the speed and safety considerations at NASA. He cautions that now, before a catastrophic accident, is the time to make sure the best possible plan is being followed, simplify things that can be simplified, and get people to the moon and back safely. Something as simple as the choice to not use hypergolic fuels means there will need to be extra equipment to reignite the engines and redundant mechanisms for such a system.
1. https://en.wikipedia.org/wiki/Apollo_1#Accident
Why did we design a system where Orion does not have enough delta-v to achieve a circularized low lunar orbit?
Is it because, for whatever reason, we didn't get the Exploration Upper Stage done?
Because Orion was not designed to go to the moon. It was designed, ostensibly, to go visit asteroids, or if you're being more cynical, it was designed to distribute tax dollars to as many districts as possible.
> Is it because, for whatever reason, we didn't get the Exploration Upper Stage done?
Reaching NRHO actually requires the Exploration Upper Stage, which is still happening.
While NASA Administrator, Michael Griffin wrote in 2007 that the shuttle program had been a colossal mistake and that Apollo-Saturn-Skylab should have continued <http://aviationweek.typepad.com/space/2007/03/human_space_ex...>:
>Let’s assume that we had kept flying with the systems we had at the time, that we had continued to execute two manned Apollo lunar missions every year, as was done in 1971-72. This would have cost about $4.8 billion annually in Fiscal 2000 dollars.
>Further, let us assume that we had established a continuing program of space station activities in Earth orbit, built on the Apollo CSM, Saturn I-B, and Skylab systems. Four crew rotation launches per year, plus a new Skylab cluster every five years to augment or replace existing modules, would have cost about $1.5 billion/year. This entire program of six manned flights per year, two of them to the Moon, would have cost about $6.3 billion annually in Fiscal 2000 dollars. The average annual NASA budget in the 15 difficult years from 1974-88 was $10.5 billion; with 60% of it allocated to human spaceflight, there would have been sufficient funding to continue a stable program of lunar exploration as well as the development of Earth orbital infrastructure. I suggest that this would have been a better strategic alternative than the choices that were in fact made, almost 40 years ago.