>There has been a lot of buzz recently about spaceflight companies shooting for frequent "airline-like operations," but scientists, engineers and policy makers generally are not "putting two and two together with respect to the emissions that are implied by that idea,"
I wouldn't worry about that. I saw Musk's video[1] on using rockets as a way to supplant air-travel and the idea is even more ridiculous than his hyperloop and underground-moving-street concepts. There's no point in mentioning it as even a possible eventuality. Rockets will never be used for intra-earth passenger travel.
I think just the opposite. Once rocketry is cheaper, not throwing the craft away with each flight, it makes perfect sense for inter-continental flights. Have a space plane for each city fly to an orbiting transfer station; passengers switch planes and arrive anywhere in the World in three hours or less.
Concord had a very limited number of viable routes which prevented the program from breaking even with the R&D costs. However, the aircraft was operated profitably later on after significant tick price increases.
A 1 hour US to Asia route that charged 50k a seat could likely be viable. That’s ultra first class, but finding ~100 passengers each way per day should be easy. It’s only expanding to more routes that would be problematic.
PS: The fuel costs would actually be comparable to a regular flight. It’s mostly a question of how many trips the rocket could make and how many passengers it could carry.
Not a chance - the Delta-v required to get to orbital velocity absolutely dwarfs that needed for suborbital hops, and your scheme also adds delays and tons of complexity.
If rocket travel ever becomes a thing, it will involve suborbital hops.
Oh Come one. What problem does rocketry solve? Right off the bat, it's horrendously expensive and it's dangerous and it's always going to be dangerous. Plus comfort ... do you think it's comfortable for passengers to be subjected to multiple G forces on launch and re-entry?
Plus we will never be able to scale rocketry to the thousands of flights per day that are occuring today (with an unbelievable safety record).
>Passengers switch planes and arrive anywhere in the World in three hours or less.
You're never going to get that. EVER. International airports today tend to be situated far from urban centers because of noise concerns, safety, and cost. These issues are magnified with rockets. Launchpads would have to be placed even further out and pre-boarding checks would take forever.
For God's sake, the Concord wasn't allowed to go supersonic until it was over open ocean. You think tens or hundreds of rocket launches per day will EVER be allowed to be anywhere near any urban center?
This is such a naive view. Rockets will never be good for passenger travel.
Is it time to recalibrate rocket technologies with added metric of pollution. Does this mean that Project Prometheus (plopping out nukes sequentially and riding the nuke push https://youtu.be/njM7xlQIjnQ?t=544) might be back on the table?
To reach the moon requires
- By chemical rocket: 1000 tons of chemical fuel for each 1 ton of payload with 1000:1 ratio roughly linear with increasing payload. Max capability today is on order of 100 tons per launch.
- By nuclear detonations: fuel:payload closer to 3:1 with prototype design of 400 ton payload for single rocket, and later designs aiming for 100,000 ton payload/rocket.
Is 30x less waste by mass better even if that waste is in part radioactive? Water waste still seems pretty good to me.
That, apart from the political and practical issues surrounding nuclear power, ignores the significant amount of pollution created during nuclear fuel enrichment.
Really, who gives a damn? Unless we are launching orbital flights at the rate we launch commercial airliners, emissions from rockets are a pisshole in the snow.
If we do ramp up to that kind of tempo, economics will spur on efficiency advances. Nipping progress in the bud now because it might be a problem some undefined period of time down the line is cowardly and depressing.
The altitude where the waste is exhausted matters too. For instance, the GHG forcing from your everyday airliner is about 3x compared to the same amount of CO2 and H20 exhausted at sea level. This difference is almost entirely due to the H20, IIRC there's no altitude dependence in CO2 emissions.
Globally, babies are born at the rate of about 145 million per year. So at the current rate of space travel a baby's chance of going into space would be about 1 in 30,000,000.
Even if space travel were increased by 3 or 4 orders of magnitude, only an insignificant percentage of people would ever travel in space. The energy requirements and expense make it a pastime for only the stupendously rich.
Wait, wtf. Do you honestly think only rich people are going to space? You know we have highly accomplished people called astronauts and cosmonauts doing scientific research, right?
Scientific research is not the objective of higher volume space tourism as planned by Blue Origin, Virgin Galactic and others. Virgin apparently sold over 700 tickets at $200K or more each for suborbital flights. Tourism to ISS is temporarily suspended due to Soyuz being the only spacecraft able to transport the astronauts and cosmonauts. https://en.wikipedia.org/wiki/Space_tourism
Given the price/performance characteristics of electromechanical relay computers, he was probably about right. The introduction of vacuum tube electronic logic, subsequently replaced by discrete transistors, and the integrated circuit logic changed the price/performance ratio by several orders of magnitude. There's the old joke about how your 1940s car would now go a million miles an hour and several million miles on a tank of gas if it had improved like computers. But we know it is a joke because physics sets bounds on the energy need to move a 1.5 ton mass, while the bounds on the energy to operate a logic gate are much lower. The same is true for spaceflight, where the formulas for rocket propelled vehicles are well understood.
The point I was trying to make is that we are only at the dawn of commercial space flight. Compare the first commercial airplane flights, technology and cost, to today's 20 euro Ryanair flights. The same will happen with space.
>The same is true for spaceflight, where the formulas for rocket propelled vehicles are well understood.
You are assuming there never will be a replacement for rocket technology. I think you're wrong.
It took about 11 years to go from Kitty Hawk to the first scheduled passenger flights in 1914. On the other hand, about 40 years elapsed between Gargarin in '61 until Dennis Tito's paid flight aboard a Soyuz in 2001.
The interval from Gargarin to now is 58 years. 58 years from 1914 puts us to 1972. By '72 we had turbofan jet airliners of all the current layouts including 4 under the wings, 2 under the wings, 2 in the tail, and different layouts of 3 in the tail. There had been the ill-fated Comet with 4 in the tail. The Concorde SST had done its first flight already in '69. There has been no comparable advance in space flight technology in the last 58 years.
Since '72 there has been cost reduction and refinement of the jet airliner, but prices also have come down due to higher volumes, more passengers per flight, and a reduction in service.
What is this new propulsion technology that you anticipate?
>There has been no comparable advance in space flight technology in the last 58 years.
Because there was no incentive. Space was something governments did and after the USA won the space race, interest waned.
SpaceX proved there is a commercial market. Now we are witnessing the start of a commercial space boom.
https://en.wikipedia.org/wiki/List_of_private_spaceflight_co...
Look at the number of launchers in development.
Competition = innovation.
And once space mining has been proven as a concept, then the real boom will begin. I'm optimistic and expect all of this to happen in the next 20 years.
>What is this new propulsion technology that you anticipate?
Ion drives?, scramjets?, something that hasn't been discovered yet?, ... I honestly don't know but I doubt we will still be stuck with chemical rockets a 100 years from now.
Every time I see this analogy, I wonder why people choose Kitty Hawk as the start date. Perhaps instead, they should treat Gagarin's flight as analogous to the flight of the Montgolfier brothers in 1783. The interval from the first manned balloon flight to the first airplane flight was 131 years, with decades of little apparent progress during that long time.
This assumes that the only way to benefit from space travel is to physically go there yourself. Communications and navigational infrastructure adds considerable quality of life to everyone.
If you want to add all the benefits, a fair consideration requires looking at all the costs, which you neglected. Pollution is but one.
I don't know enough to say where the cost-benefit analysis ends up, but I'm inclined to believe some rockets overall benefit humanity, like launching satellites to help solve our environmental challenges, but many don't, like space tourism.
I don't have a fixed view on rockets. I helped build an x-ray observational satellite in orbit, but I don't agree with a view common on HN that space travel an unqualified good or necessary today.
The early communications satellites were launched with Thor-Delta and Delta rockets. In general, communications satellites reached low earth orbit before manned spacecraft, and satellites where put into geosynchronous orbit before manned spacecraft passed that altitude on the way to the moon. Manned spacecraft have never operated in geosynchronous orbit, since it is beyond the Van Allen belts and exposed to cosmic radiation.
I fully support the continued development and operation of all kinds of satellites for communications, earth monitoring, astronomy, etc., as well as the development and operation of spacecraft for lunar and planetary exploration. However, people are not suited for space travel since they are fragile and weigh too much, especially when all the life support overhead is factored in.
And the number of people who could be addressed at once was once limited to an auditorium.
Rockets to Earth orbit are the bootstrap stage, like electro-mechanical relays are to transistors. We will have orders-of-magnitude more efficient methods, and they will bring humanity to space and its treasures to us, without dumping chemicals into the air.
Rocket launches presently have a small effect on total stratospheric ozone (much less than 0.1%). Space industry developments indicate that rocket emissions may increase more significantly than reported in the previous Assessment. Their impacts will depend on rocket design (particularly the altitude of emissions), launch vehicle sizes, launch rates, spaceport locations, and fuel types. Important gaps remain in understanding rocket emissions and their combined chemical, radiative, and dynamical impacts on the global stratosphere and in projections of launch rates. These gaps limit the confidence level of predictions of present and future impacts of rocket emissions on stratospheric ozone and suggest periodic assessments are warranted. The lifetime of the most important rocket emissions is limited, and the stratospheric accumulation of rocket-emitted black carbon and alumina particles varies in correspondence with global launch rates and altitude of emissions.
Exactly - at the current phase of our civilization space travel is pretty much the only thing that makes sense & we shoould use every opportunity we have to make our species (at least) multi-planetary before and internal or external catastrophe closes the currently open window of space travel.
This way we can protect our species from getting wiped out with our single habitat, as well as likely solving all our resource and energy issues with the wastly bigger resources of space compared to what we would have available if we never leave the planet.
Speed of light being the ultimate barrier and our own solar system being the way it is (ie: no other habitable planets) means we will never be a "multi-planetary species". Being able to leave the planet for some colonization of the universe is a pipe dream, Star Trek is never going to be real.
We'll have to learn to make do with what's on our planet, instead of continuing on the current path in unrealistic hopes of serving on the USS Enterprise.
Spacefaring is more likely than multi-planetary. Do you disagree with any point below?
(1) We use factories and raw materials to build space station modules.
(2) We create and expand space stations in Earth orbit by launching modules via rockets.
(3) We can build and add additional modules to increase the crew capacity of the station.
(4) We grow plants and manufacture things (in small quantities) on the station.
(5) We live (in small numbers) on space stations for years given enough crew space and constant coordination and resupply shipments from Earth.
(6) The amount of people and equipment directly involved in any particular Earth industry is finite.
(7) We protect volumes from the hazards of space (vacuum, temperature, micro-meteors, radiation) by armoring their surfaces with factory-made materials.
(8) We could continue (2 and 7) until the station is armored enough to allow its inhabitants and equipment to survive beyond Earth's magnetic shield.
(9) Given (5), we could continue (2 and 3) until the station has enough people (6) to self-co-administer, at which point it only needs resupply shipments from Earth to sustain itself.
(10) We could continue (2 and 4) until the station has enough factories and refineries for (1), provided it has raw materials from Earth or asteroids.
(11) We could build one or more hospital modules to facilitate safe human births on the station, perhaps in a rotating section, so new humans can replace the old.
To accomplish these points, we require no additional advances in technology, only our sustained effort. Humanity could live and grow endlessly in large space stations that run on solar power and build with raw materials from asteroids, comets, moons, or planets.
And what would that get us? A station permanently dependent on getting raw materials from earth. Nothing gained, really - except more pollution on the surface and a habitat really not suited to humans.
We can grow plants on Earth, why would we do it in orbit.
A station does not have to be entirely depended on earth, there are a lot of raw materials in space.
As for some reasons to grow, or manufacture really, things in orbit, landmass is one reason. There is a whole lot of real estate up there that we don't really have access to on earth. There is also the ability to send down materials to anywhere on earth without requiring a huge transportation network that causes things like roadway congestion. On top of those, building facilities that do heavy amounts of nasty polluting become less of a concern. It's not really as much of an issue to dump a bunch of toxic stuff into space compared to say, a river. I suspect nuclear power plants also start to become more viable as there is less of a worry over meltdowns as you're already surrounded by massive amounts of radiation and have no population to evacuate.
5. There’s a limit to time in space without long term injury.
8-10. You conclude we can continue indefinitely, but make no effort to show that this is the case — or that the amount needed wouldn’t end civilization prior to success.
11. It’s not clear to me you can have a pregnancy in space, given the health impacts to astronauts.
Until we can demonstrate we can look after our single habitat, and demonstrate terraforming or a sealed habitat that's proven viable indefinitely, why would we look to space and multi-planetary? Seems like extreme and dangerous hubris to prioritise that over getting here long term viable first. Or a way to avoid the issue while civilisation crashes...
Quite apart from not having a suitable planet in reachable range. Mars doesn't really cut it - that puts humanity's future in a sealed tin can or needs terraforming.
Humanity now has the capacity to anhaliate all people from the Earth within a year with our nuclear arsenals. Even though Mutually Assured Destruction has prevented this from happening yet, the statistics point to inevitable doom on a long enough timescale. Hell, we nearly wiped ourselves out several times since 1950. In such an environment, it makes sense to push towards interplanetary colonization as quickly as possible.
> space travel is pretty much the only thing that makes sense
There are plenty of things we can do. We can be more harmonious to our planet, for one. We can learn to make the atacama or sahara deserts habitable. We can learn to stop the climate shift we seem to be experiencing. We can be more harmonious to the other humans on this planet.
These are all big ticket items that will still exist even if we found some garden of eden on some far off shore. I can't think of anything worse than taking our mining and destructive natures to an innocent planet. We have created this planet's problems. We should fix them before shooting moonbeams and running away from them.
Yeah, pretty much. Space travel and space colonisation are basically civilisation/world ending disaster insurance, which is something that's likely going to be needed more and more as time goes on. Want the best chance of not seeing civilisation wrecked by a solar flare/meteor/nuclear war/other disaster? Have multiple other settlements on other planets/moons.
There's also that point where the sun will become a red giant or something and Earth will physically be unable to support life, but there's at least 600 million years before that one becomes an issue, and I'm sure something would have figured out space travel before then.
It's like running a large website and using multiple servers/cloud hosting/multiple datacentres. Or hosting your site, domain and email at different providers. Makes it far less likely the whole system will collapse at once.
> At a constant acceleration of 1 g, a rocket could travel the diameter of our galaxy in about 12 years ship time, and about 113,000 years planetary time. If the last half of the trip involves deceleration at 1 g, the trip would take about 24 years. If the trip is merely to the nearest star, with deceleration the last half of the way, it would take 3.6 years.
24 years is one generation of humans. And 113,000 years is still less than 600 million years. Speed of light is not a problem. Making that ship self-sustainable and even being able to accelerate to 0.999 c might be.
It's also probably worth pointing out that the future of space travel may not be trips made by people in their lifetimes with the knowledge of science that exists now.
If we can somehow figure out how to keep astronauts in stasis some way or the other, that would remove the need to get anywhere in under 100 years or so. If humans become cyborgs and lose the need for standard forms of nutrition or air, that helps too. If methods for life extension are found, the same.
And if that fails, well there's always robots. Or potentially colony ships. Nothing says the automated ship has to be 'on' for the duration of the journey, only the launch and destination.
with any of these ideas, the speed of light becomes even less of an issue.
Unless I've missed some news, living on another planet is absolutely not something to rely on for this century.
There are local solutions for global warming, it's simply to consume less, people in developed countries could consume roughly 20x less, which is already more than enough (I can relate), and apply a sort of birth-control globally
Space travel sounds like the apogee of consumerism, it's possible to live differently, durably on this planet
Yes, and no. We're still very far from achieving anything close to space colonies not dependent on earth, so no, we can't afford to no longer care about the earth. Climate change, biodiversity loss, topsoil loss, and whatever are serious environmental issues that require solving on a relatively short scale compared to colonizing other planets.
But it doesn't have to mean we put a full stop on all space activity. But rather that we research what the effects are, and take measures to reduce those effects to the extent they can be done at reasonable cost. Say, if alumina and chlorine compounds from solid rocket boosters are bad, maybe we should use liquid fueled rockets. If soot from RP-1 is a problem, maybe think about switching to, say, methane.
The implication in the article is that the exhaust gases may not be as significant as the metallic debris that vaporizes in the atmosphere. It sounds very unnatural for the atmosphere to have to deal with this, but here’s an interesting quote regarding meteorites (natural metallic debris):
I do think that it's a good idea to do some research in the area, a really good idea. We've assumed far too much about the resiliency of our environment.
With that said, I would be quite surprised if unspecific metal debris/dust is going to have any major effects, except as it already is as a threat to the functionality of satellites, space stations, and rockets.
The meteorite argument is quite strong, but not unassailable, as meteorites in general has a chemical composition that is quite different from space hardware.
Not that we use a lot of Antimony in rockets, but it works as en example. If I interpreted the numbers correctly, we can put an upper limit on the contribution of atmospheric Antimony from 78000 tons of meteorites at ~16 kg, or roughly 35 lbs.
Thus, it's not entirely impossible that some of the space hardware over it's life, and death, can contribute more of certain unusual elements to the atmosphere than meteorites do in the same period.
Organic molecules however, those are a bit more concerning, as we already know that some species can greatly affect our atmosphere!
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[ 9.6 ms ] story [ 125 ms ] threadI wouldn't worry about that. I saw Musk's video[1] on using rockets as a way to supplant air-travel and the idea is even more ridiculous than his hyperloop and underground-moving-street concepts. There's no point in mentioning it as even a possible eventuality. Rockets will never be used for intra-earth passenger travel.
[1]https://www.space.com/38314-elon-musk-spacex-mars-rocket-ear...
Flight times of an hour from anywhere on the planet to anywhere IIRC
A 1 hour US to Asia route that charged 50k a seat could likely be viable. That’s ultra first class, but finding ~100 passengers each way per day should be easy. It’s only expanding to more routes that would be problematic.
PS: The fuel costs would actually be comparable to a regular flight. It’s mostly a question of how many trips the rocket could make and how many passengers it could carry.
If rocket travel ever becomes a thing, it will involve suborbital hops.
Plus we will never be able to scale rocketry to the thousands of flights per day that are occuring today (with an unbelievable safety record).
>Passengers switch planes and arrive anywhere in the World in three hours or less.
You're never going to get that. EVER. International airports today tend to be situated far from urban centers because of noise concerns, safety, and cost. These issues are magnified with rockets. Launchpads would have to be placed even further out and pre-boarding checks would take forever.
For God's sake, the Concord wasn't allowed to go supersonic until it was over open ocean. You think tens or hundreds of rocket launches per day will EVER be allowed to be anywhere near any urban center?
This is such a naive view. Rockets will never be good for passenger travel.
To reach the moon requires - By chemical rocket: 1000 tons of chemical fuel for each 1 ton of payload with 1000:1 ratio roughly linear with increasing payload. Max capability today is on order of 100 tons per launch. - By nuclear detonations: fuel:payload closer to 3:1 with prototype design of 400 ton payload for single rocket, and later designs aiming for 100,000 ton payload/rocket.
Is 30x less waste by mass better even if that waste is in part radioactive? Water waste still seems pretty good to me.
https://newatlas.com/orion-project-atom-bomb-spaceship/49454...
If we do ramp up to that kind of tempo, economics will spur on efficiency advances. Nipping progress in the bud now because it might be a problem some undefined period of time down the line is cowardly and depressing.
Globally, babies are born at the rate of about 145 million per year. So at the current rate of space travel a baby's chance of going into space would be about 1 in 30,000,000.
Even if space travel were increased by 3 or 4 orders of magnitude, only an insignificant percentage of people would ever travel in space. The energy requirements and expense make it a pastime for only the stupendously rich.
"I think there is a world market for maybe five computers."
Thomas Watson, president of IBM, 1943
>The same is true for spaceflight, where the formulas for rocket propelled vehicles are well understood.
You are assuming there never will be a replacement for rocket technology. I think you're wrong.
The interval from Gargarin to now is 58 years. 58 years from 1914 puts us to 1972. By '72 we had turbofan jet airliners of all the current layouts including 4 under the wings, 2 under the wings, 2 in the tail, and different layouts of 3 in the tail. There had been the ill-fated Comet with 4 in the tail. The Concorde SST had done its first flight already in '69. There has been no comparable advance in space flight technology in the last 58 years.
Since '72 there has been cost reduction and refinement of the jet airliner, but prices also have come down due to higher volumes, more passengers per flight, and a reduction in service.
What is this new propulsion technology that you anticipate?
Because there was no incentive. Space was something governments did and after the USA won the space race, interest waned. SpaceX proved there is a commercial market. Now we are witnessing the start of a commercial space boom. https://en.wikipedia.org/wiki/List_of_private_spaceflight_co... Look at the number of launchers in development. Competition = innovation. And once space mining has been proven as a concept, then the real boom will begin. I'm optimistic and expect all of this to happen in the next 20 years.
>What is this new propulsion technology that you anticipate?
Ion drives?, scramjets?, something that hasn't been discovered yet?, ... I honestly don't know but I doubt we will still be stuck with chemical rockets a 100 years from now.
I don't know enough to say where the cost-benefit analysis ends up, but I'm inclined to believe some rockets overall benefit humanity, like launching satellites to help solve our environmental challenges, but many don't, like space tourism.
post curiosity edit: Heck, your own thesis hinged on observations that necessarily had to be done in space.
https://en.wikipedia.org/wiki/Delta_(rocket_family)
I fully support the continued development and operation of all kinds of satellites for communications, earth monitoring, astronomy, etc., as well as the development and operation of spacecraft for lunar and planetary exploration. However, people are not suited for space travel since they are fragile and weigh too much, especially when all the life support overhead is factored in.
Rockets to Earth orbit are the bootstrap stage, like electro-mechanical relays are to transistors. We will have orders-of-magnitude more efficient methods, and they will bring humanity to space and its treasures to us, without dumping chemicals into the air.
Rocket launches presently have a small effect on total stratospheric ozone (much less than 0.1%). Space industry developments indicate that rocket emissions may increase more significantly than reported in the previous Assessment. Their impacts will depend on rocket design (particularly the altitude of emissions), launch vehicle sizes, launch rates, spaceport locations, and fuel types. Important gaps remain in understanding rocket emissions and their combined chemical, radiative, and dynamical impacts on the global stratosphere and in projections of launch rates. These gaps limit the confidence level of predictions of present and future impacts of rocket emissions on stratospheric ozone and suggest periodic assessments are warranted. The lifetime of the most important rocket emissions is limited, and the stratospheric accumulation of rocket-emitted black carbon and alumina particles varies in correspondence with global launch rates and altitude of emissions.
Space travel seems like it should be a priority for humanity. More so than the latest iPhone and all that other crap that produces pollution
This way we can protect our species from getting wiped out with our single habitat, as well as likely solving all our resource and energy issues with the wastly bigger resources of space compared to what we would have available if we never leave the planet.
We'll have to learn to make do with what's on our planet, instead of continuing on the current path in unrealistic hopes of serving on the USS Enterprise.
(1) We use factories and raw materials to build space station modules.
(2) We create and expand space stations in Earth orbit by launching modules via rockets.
(3) We can build and add additional modules to increase the crew capacity of the station.
(4) We grow plants and manufacture things (in small quantities) on the station.
(5) We live (in small numbers) on space stations for years given enough crew space and constant coordination and resupply shipments from Earth.
(6) The amount of people and equipment directly involved in any particular Earth industry is finite.
(7) We protect volumes from the hazards of space (vacuum, temperature, micro-meteors, radiation) by armoring their surfaces with factory-made materials.
(8) We could continue (2 and 7) until the station is armored enough to allow its inhabitants and equipment to survive beyond Earth's magnetic shield.
(9) Given (5), we could continue (2 and 3) until the station has enough people (6) to self-co-administer, at which point it only needs resupply shipments from Earth to sustain itself.
(10) We could continue (2 and 4) until the station has enough factories and refineries for (1), provided it has raw materials from Earth or asteroids.
(11) We could build one or more hospital modules to facilitate safe human births on the station, perhaps in a rotating section, so new humans can replace the old.
To accomplish these points, we require no additional advances in technology, only our sustained effort. Humanity could live and grow endlessly in large space stations that run on solar power and build with raw materials from asteroids, comets, moons, or planets.
We can grow plants on Earth, why would we do it in orbit.
As for some reasons to grow, or manufacture really, things in orbit, landmass is one reason. There is a whole lot of real estate up there that we don't really have access to on earth. There is also the ability to send down materials to anywhere on earth without requiring a huge transportation network that causes things like roadway congestion. On top of those, building facilities that do heavy amounts of nasty polluting become less of a concern. It's not really as much of an issue to dump a bunch of toxic stuff into space compared to say, a river. I suspect nuclear power plants also start to become more viable as there is less of a worry over meltdowns as you're already surrounded by massive amounts of radiation and have no population to evacuate.
5. There’s a limit to time in space without long term injury.
8-10. You conclude we can continue indefinitely, but make no effort to show that this is the case — or that the amount needed wouldn’t end civilization prior to success.
11. It’s not clear to me you can have a pregnancy in space, given the health impacts to astronauts.
The only thing that makes sense? You can't think of any other problems that we might work on first?
Quite apart from not having a suitable planet in reachable range. Mars doesn't really cut it - that puts humanity's future in a sealed tin can or needs terraforming.
There are plenty of things we can do. We can be more harmonious to our planet, for one. We can learn to make the atacama or sahara deserts habitable. We can learn to stop the climate shift we seem to be experiencing. We can be more harmonious to the other humans on this planet.
These are all big ticket items that will still exist even if we found some garden of eden on some far off shore. I can't think of anything worse than taking our mining and destructive natures to an innocent planet. We have created this planet's problems. We should fix them before shooting moonbeams and running away from them.
There's also that point where the sun will become a red giant or something and Earth will physically be unable to support life, but there's at least 600 million years before that one becomes an issue, and I'm sure something would have figured out space travel before then.
It's like running a large website and using multiple servers/cloud hosting/multiple datacentres. Or hosting your site, domain and email at different providers. Makes it far less likely the whole system will collapse at once.
> At a constant acceleration of 1 g, a rocket could travel the diameter of our galaxy in about 12 years ship time, and about 113,000 years planetary time. If the last half of the trip involves deceleration at 1 g, the trip would take about 24 years. If the trip is merely to the nearest star, with deceleration the last half of the way, it would take 3.6 years.
24 years is one generation of humans. And 113,000 years is still less than 600 million years. Speed of light is not a problem. Making that ship self-sustainable and even being able to accelerate to 0.999 c might be.
[1] https://en.wikipedia.org/wiki/Space_travel_using_constant_ac...
If we can somehow figure out how to keep astronauts in stasis some way or the other, that would remove the need to get anywhere in under 100 years or so. If humans become cyborgs and lose the need for standard forms of nutrition or air, that helps too. If methods for life extension are found, the same.
And if that fails, well there's always robots. Or potentially colony ships. Nothing says the automated ship has to be 'on' for the duration of the journey, only the launch and destination.
with any of these ideas, the speed of light becomes even less of an issue.
There are local solutions for global warming, it's simply to consume less, people in developed countries could consume roughly 20x less, which is already more than enough (I can relate), and apply a sort of birth-control globally
Space travel sounds like the apogee of consumerism, it's possible to live differently, durably on this planet
But it doesn't have to mean we put a full stop on all space activity. But rather that we research what the effects are, and take measures to reduce those effects to the extent they can be done at reasonable cost. Say, if alumina and chlorine compounds from solid rocket boosters are bad, maybe we should use liquid fueled rockets. If soot from RP-1 is a problem, maybe think about switching to, say, methane.
“Estimates for the mass of material that falls on Earth each year range from 37,000-78,000 tons. Most of this mass would come from dust-sized particles.” http://curious.astro.cornell.edu/about-us/75-our-solar-syste...
With that said, I would be quite surprised if unspecific metal debris/dust is going to have any major effects, except as it already is as a threat to the functionality of satellites, space stations, and rockets.
The meteorite argument is quite strong, but not unassailable, as meteorites in general has a chemical composition that is quite different from space hardware.
Not that we use a lot of Antimony in rockets, but it works as en example. If I interpreted the numbers correctly, we can put an upper limit on the contribution of atmospheric Antimony from 78000 tons of meteorites at ~16 kg, or roughly 35 lbs.
Thus, it's not entirely impossible that some of the space hardware over it's life, and death, can contribute more of certain unusual elements to the atmosphere than meteorites do in the same period.
Organic molecules however, those are a bit more concerning, as we already know that some species can greatly affect our atmosphere!