Who knew steam punk would come in handy :-) Seriously though it is an excellent thought experiment to design a purely mechanical rover. The concept of using a windmill to wind a spring is pretty neat, although at 850 degrees its going to be a challenge to find a spring material.
>although at 850 degrees its going to be a challenge to find a spring material.
Google "Exhaust heat riser"
A spring that provides many years of useful service when exposed to high temperatures isn't a very exotic part. NASA probably isn't trying to make it go 5yr/50,000mi without failing so they can probably come up with something that works well for the duration of the mission.
Although most heat risers seem to simply be a bi-metal allow which changes shape when hot. The article discusses winding springs much like a clock maker would use.
That said, a bit of searching did find Iconel 718 springs which are good up to 1000 degrees. Not a lot of margin but probably workable. Since people has developed techniques for 3D printing Iconel 718 it seems like that problem at least is workable.
Digging machines are quite complex and prone to failure (that is one area where humanity is basically nowhere compared to biologicals), you'd have trouble exfiltering the information, and packing the analysis ware would be even more difficult than in a surface rover.
We are fairly far behind but nature does have it a bit easier because animals are making much smaller holes through dirt and soil instead of solid rock like most human tunnels want to go through. Also they can just avoid any particularly difficult areas and move somewhere else.
Burrowing through anything other than loosely packed soil by necessity creates a larger volume of tailings than the original rock which has to be constantly cleared to the surface. Packing a useful science lab into a robot small enough to burrow through loose top soil on Venus (which may or may not be very deep or even really exist since we know very little about the surface of Venus) would be difficult to impossible. Second in the case of going through hard rock via drilling, the drill teeth have a limited life span and would be extremely difficult to replace in an automated way.
The WIRED article has errors. They got the PI's name wrong. They also say this about communications:
"the Venus rover will use a simple optical reflector to transmit its data to orbiting satellites by flashing radar light like morse code"
This is misleading in a couple of ways. The rover in the link above appears to use radar targets which turn on wheels; an orbiter would bounce radio off the target to determine their configuration.
Did ancient Earth have a more Venus-like atmosphere? If not, what's responsible for the difference? Is it due to the extra solar energy that Venus receives?
Short story is that the well-known sulfuric acid clouds are produced by plentiful CO2 combining in the atmosphere with trace SO2 and H2O gases. The high temperatures prevent the CO2 and SO2 from being captured into minerals, as they are on Earth. More:
This caused me to search for very high temperature semiconductors. It turns out there are some rated for 300 to 400C operation. This mission seems to require 450C+ but that's close. This seems like another area where RISC-V would be very beneficial, as the companies that make very high temperature chips could benefit greatly from an open instruction set with simple free designs. One company had 8051s rated over 200C, but that arch is a bit dated.
I wonder if it would be easier to find discrete components that work at high temperature. And use a vacuum tube instead of a transistor - vacuum tubes can handle high temperature easily.
Put all of them in a single strong container instead of using lots of fragile glass in a high pressure environment. And you won't need to heat the emitter, saving weight.
I thought one idea for Venus was to have a balloon with a gondola that would float high in the atmosphere, that way it wouldn't have to handle extreme temperature and it would just need to deal with the occasional sulfuric acid thunderstorm!
I find the idea of an essentially clockwork rover really interesting but from a practical standpoint I still think the ideal rover for Venus would be like a cross between an submersible and an airship.
When the rover starts to run out of coolant it would inflate the airbag, rise up to about the one atmosphere level (50km?), use solar power to replace the coolant, then descend again for another ground mission. And since the venusian atmosphere is about 5% nitrogen, nitrogen seems like the ideal coolant, and, on top of that, it's probably the ideal lift gas for Venus as well. This is because pure gaseous nitrogen is considerably less dense than gaseous carbon dioxide.
I wonder if we should be exploring the atmosphere of Venus instead anyway. My understanding is the best chance of life is in the upper atmosphere anyway.
They'll move you along, but as long as there's little turbulence or wind shear, it won't damage anything. And given that the wind moves in a consistent direction and speed varies mostly just with altitude, I doubt there's much of either.
According to wikipedia, winds are pretty slow near the surface. Strong winds at high altitudes might be a problem if there's turbulence, but if there isn't it's probably okay.
> Thermal inertia and the transfer of heat by winds in the lower atmosphere mean that the temperature of Venus's surface does not vary significantly between the night and day sides, despite Venus's extremely slow rotation. Winds at the surface are slow, moving at a few kilometres per hour, but because of the high density of the atmosphere at the surface, they exert a significant amount of force against obstructions, and transport dust and small stones across the surface. This alone would make it difficult for a human to walk through, even if the heat, pressure, and lack of oxygen were not a problem.
...
> The only appreciable variation in temperature occurs with altitude. The highest point on Venus, Maxwell Montes, is therefore the coolest point on Venus, with a temperature of about 655 K (380 °C; 715 °F) and an atmospheric pressure of about 4.5 MPa (45 bar).
...
> Strong 300 km/h (185 mph) winds at the cloud tops go around Venus about every four to five Earth days.
That got me curious how slow Venus rotates and apparently it takes 243 Earth days for a single day to pass there. Which is even more amazing considering it takes Venus only 224 Earth days to orbit Sun - a single day there takes more than 1 year! Developing inter-planetary software would have interesting surprises...
It's an airship, so all that matters is shear. If it doesn't have to have zero groundspeed then it doesn't matter how fast the wind is blowing, just go that direction.
See this page on extreme temperature electronics for a good discussion of what is available on the electronics side. The short answer is, there are discrete components that have been demonstrated to temperatures higher than Venus's 460C but little commercially available. In particular no integrated circuits. http://www.extremetemperatureelectronics.com/tutorial1.html
> Those treads are powered via a wind turbine that captures the planet’s whipping wind gusts
This seems odd to me - Venus has high wind speeds in the upper atmosphere, but on the surface the winds are only one or two m/s. Is that enough to wind a spring?
> Savonius turbines are used whenever cost or reliability is much more important than efficiency.
The German article is a bit more detailed and claims that Savonius tubines are effective at speeds as low as 2m/s and produce high torque even then. Maybe the high pressure on Venus increases this effect?
I used to do research in a lab which studied extreme temperature electronics using Silicon Carbide CMOS. These electronics are able to handle over 450 C ambient temperatures and may be able to survive in the Venusian atmosphere with minimal shielding. Looks like they started a company and have funding for jet engine electronics.
This is a great example of space exploration that could produce technology relevant for applications on Earth: If you have a complex machine that can do usefuk work on Venus, you can use a similar concept for ultra-durable equipment here. Stuff like this could be relevant for deep sea exploration, nuclear applications, mining and so on.
Why not just design for deep sea exploration or nuclear applications directly? It's a heck of a lot cheaper to test prototypes in the ocean than on Venus.
> The Venera 9 and 10 landers had two cameras each. Only one functioned because the lens covers failed to separate from the second camera on each lander. The design was changed for Venera 11 and 12, but this change made the problem worse and all cameras failed on those missions. Venera 13 and 14 were the only landers on which all cameras worked properly; although unfortunately, the titanium lens cap on Venera 14 landed precisely on the area which was targeted by the soil compression probe.
Yes, the issue was stupidly trivial. They put a very tight fitting steel cap on an aluminium camera housing.
They attempted to over-engineer the thing further by adding explosive bolts to it. That also ended in failure (explosives failed to explode as they decomposed long before they were fired).
Finally, a dumb solution was devised: to make the cap to fit inside the bezel and be made from titanium. That finally solved the issue.
As the aluminium bezel expanded, the cap loosened up, falling out under its own weight.
But that didn't account for another instrument sampling area being right under the camera, where the cap were to fall.
Venus is so strangely ignored and forgotten. Measured against the attention other planets are getting, an orbiting reconnaissance platform with a handfull of atmosphere and surface probes would seem long overdue.
Well one reason is because it's so hot there there is almost no chance to find life or to build a station there. Also I wonder if it is because the Russians set to explore it, landed a probe on it and all. So maybe then it became uninteresting to follow in their footsteps. Just like the Russians stopped sending rovers to the moon once Americans landed there.
Not just the heat, but also the sulphuric acid rain and the 90atm of pressure. I do find it odd though, that this curious planet with heaps of activity is so often 'passed over' by space nerds.
Curiously, the earliest out-of-lab digital photography that I'm aware of was from that Russian probe to Venus in the 70's, which lasted less than an hour in the hostile atmosphere.
It has the interesting property of about 50km above the surface being the only place in the solar system - other than Earth obviously - where a human being could survive without a space suit, just with an oxygen supply. The pressure and temperature are exactly like on a normal Earth day(1atm and around 0-20C). Floating barges high up in Venus atmosphere have been suggested previously.
Interestingly, there is actually a case to be made that Venus may be more feasible to colonize than Mars. It has been argued the lack of attention to Venus has more to due culture than science. PBS Spacetime did an episode on this: https://m.youtube.com/watch?v=gJ5KV3rzuag
Japan has an orbiter there already (https://en.wikipedia.org/wiki/Akatsuki_(spacecraft) ), though it had a few bumps getting into orbit on the way over. However, the environment is very hostile, which makes a rover a much more difficult proposition. Also it's actually more difficult to move towards the inner planets because you can't easily use gravitational slingshots to help save fuel (and for other reasons).
> [The new rover] is a great example of counterintuitive problem solving. Instead of packing high-tech electronics into its frame, the scientists are building a mechanical rover that works with minimal electronics.
Really? Is that counterintuitive? If you talk to car or motorcycle overland travellers who traverse deserts and remote mountains, you'll find a preference for simple designs that minimize part counts and electronics (for fuel pump, ABS, suspension...) to improve reliability, often at the cost of performance and efficiency.
I am always amazed by the images the USSR missions were able to send back from the Venus surface in the freaking 70's and early 80's [1][2]. For a very long time that were the only 'real' pictures from another planet. So good looking and from such a hostile environment.
62 comments
[ 2.6 ms ] story [ 93.8 ms ] threadGoogle "Exhaust heat riser"
A spring that provides many years of useful service when exposed to high temperatures isn't a very exotic part. NASA probably isn't trying to make it go 5yr/50,000mi without failing so they can probably come up with something that works well for the duration of the mission.
That said, a bit of searching did find Iconel 718 springs which are good up to 1000 degrees. Not a lot of margin but probably workable. Since people has developed techniques for 3D printing Iconel 718 it seems like that problem at least is workable.
[1] https://www.youtube.com/watch?v=qNk_T82iuHM
All the samples you need, with only a part of the pressure and none of the toxic atmosphere?
I know it would not make scenic photos- and take forever to get anywhere- but it would last.
Also that still leaves dealing with the tailings.
https://www.nasa.gov/feature/jpl/a-clockwork-rover-for-venus
The WIRED article has errors. They got the PI's name wrong. They also say this about communications:
"the Venus rover will use a simple optical reflector to transmit its data to orbiting satellites by flashing radar light like morse code"
This is misleading in a couple of ways. The rover in the link above appears to use radar targets which turn on wheels; an orbiter would bounce radio off the target to determine their configuration.
https://en.wikipedia.org/wiki/Atmosphere_of_Venus#Clouds
Put all of them in a single strong container instead of using lots of fragile glass in a high pressure environment. And you won't need to heat the emitter, saving weight.
If there are, it might feel completely at home on Venus.
When the rover starts to run out of coolant it would inflate the airbag, rise up to about the one atmosphere level (50km?), use solar power to replace the coolant, then descend again for another ground mission. And since the venusian atmosphere is about 5% nitrogen, nitrogen seems like the ideal coolant, and, on top of that, it's probably the ideal lift gas for Venus as well. This is because pure gaseous nitrogen is considerably less dense than gaseous carbon dioxide.
That sounds like a horrible idea.
NASA's proposal:
https://en.m.wikipedia.org/wiki/High_Altitude_Venus_Operatio...
I am fond of the name HAVOC.
> Thermal inertia and the transfer of heat by winds in the lower atmosphere mean that the temperature of Venus's surface does not vary significantly between the night and day sides, despite Venus's extremely slow rotation. Winds at the surface are slow, moving at a few kilometres per hour, but because of the high density of the atmosphere at the surface, they exert a significant amount of force against obstructions, and transport dust and small stones across the surface. This alone would make it difficult for a human to walk through, even if the heat, pressure, and lack of oxygen were not a problem.
...
> The only appreciable variation in temperature occurs with altitude. The highest point on Venus, Maxwell Montes, is therefore the coolest point on Venus, with a temperature of about 655 K (380 °C; 715 °F) and an atmospheric pressure of about 4.5 MPa (45 bar).
...
> Strong 300 km/h (185 mph) winds at the cloud tops go around Venus about every four to five Earth days.
https://en.wikipedia.org/wiki/Venus#Atmosphere_and_climate
Given the thickness of the atmosphere, maybe the most sensible form of locomotion on the surface is to just let the wind carry you along...
That got me curious how slow Venus rotates and apparently it takes 243 Earth days for a single day to pass there. Which is even more amazing considering it takes Venus only 224 Earth days to orbit Sun - a single day there takes more than 1 year! Developing inter-planetary software would have interesting surprises...
https://news.ycombinator.com/item?id=14965655
This seems odd to me - Venus has high wind speeds in the upper atmosphere, but on the surface the winds are only one or two m/s. Is that enough to wind a spring?
> Savonius turbines are used whenever cost or reliability is much more important than efficiency.
The German article is a bit more detailed and claims that Savonius tubines are effective at speeds as low as 2m/s and produce high torque even then. Maybe the high pressure on Venus increases this effect?
http://news.uark.edu/articles/39133/ozark-integrated-circuit... http://www.ozarkic.com/our-services/high-temperature/
https://en.wikipedia.org/wiki/Venera#Venera_camera_successes...
> The Venera 9 and 10 landers had two cameras each. Only one functioned because the lens covers failed to separate from the second camera on each lander. The design was changed for Venera 11 and 12, but this change made the problem worse and all cameras failed on those missions. Venera 13 and 14 were the only landers on which all cameras worked properly; although unfortunately, the titanium lens cap on Venera 14 landed precisely on the area which was targeted by the soil compression probe.
They attempted to over-engineer the thing further by adding explosive bolts to it. That also ended in failure (explosives failed to explode as they decomposed long before they were fired).
Finally, a dumb solution was devised: to make the cap to fit inside the bezel and be made from titanium. That finally solved the issue.
As the aluminium bezel expanded, the cap loosened up, falling out under its own weight.
But that didn't account for another instrument sampling area being right under the camera, where the cap were to fall.
Curiously, the earliest out-of-lab digital photography that I'm aware of was from that Russian probe to Venus in the 70's, which lasted less than an hour in the hostile atmosphere.
Photos: https://nssdc.gsfc.nasa.gov/imgcat/html/mission_page/VN_Vene...
Really? Is that counterintuitive? If you talk to car or motorcycle overland travellers who traverse deserts and remote mountains, you'll find a preference for simple designs that minimize part counts and electronics (for fuel pump, ABS, suspension...) to improve reliability, often at the cost of performance and efficiency.
[1] http://mentallandscape.com/C_Venera_Perspective.jpg
[2] http://mentallandscape.com/C_CatalogVenus.htm