4 ms·

if anyone has worked at JPL or similar, what's the best resource for learning how to make an actual Mars/Moon rover? I'm very curious about things like, what k

by tomp 8y ago

if anyone has worked at JPL or similar, what's the best resource for learning how to make an actual Mars/Moon rover? I'm very curious about things like, what kind of wheels you need for regolith, how to manage extreme temperatures (electronics, motors, batteries, cameras), how communication works (could you have a remotely-operated lunar rover?), dealing with radiation (SpaceX works with consumer electronics AFAIK, but they mostly fly within Earth's magnetosphere, which ... changes things). Any replies or emails would be extremely appreciated.

ncol 8y ago
Haven't worked in this field, but here are some episodes discussing the topic: https://www.youtube.com/watch?v=nJLOZDPTp3I https://www.youtube.com/watch?v=nJLOZDPTp3I https://www.youtube.com/watch?v=ADJwChUtdDQ https://www.youtube.com/watch?v=ADJwChUtdDQ https://theamphour.com/334-an-interview-with-gerry-roston/ https://theamphour.com/334-an-interview-with-gerry-roston/ https://theamphour.com/220-an-interview-with-shaun-meehan-doctiloquent-dove-deployer/ https://theamphour.com/220-an-interview-with-shaun-meehan-do... https://theamphour.com/401-an-interview-with-brent-and-bryce-salmi/ https://theamphour.com/401-an-interview-with-brent-and-bryce... https://www.youtube.com/watch?v=FzRP1qdwPKw https://www.youtube.com/watch?v=FzRP1qdwPKw I think what you are talking about is mostly just normal engineering in the sense that the process is similar. What really makes space unique isn't space as such but that there is no real-world (real-space?) testing, no inspections after the fact or do-overs.
- radiorental 8y ago
  > What really makes space unique isn't space as such but that there is no real-world (real-space?) testing, no inspections after the fact or do-overs. This is becoming less true today as engineering problems become more complex and simulation tools become more capable. Most automotive manufacturers have virtual models of their vehicles in testing long before the first nut meets it's bolt.
- joshvm 8y ago
  >I think what you are talking about is mostly just normal engineering in the sense that the process is similar. What really makes space unique isn't space as such but that there is no real-world (real-space?) testing, no inspections after the fact or do-overs. This is sort of true? Spacecraft of all types are subject to a battery of physical tests before launch. This includes vacuum testing, thermal cycling and vibration (where many parts fail). There are normally duplicate components produced for different purposes. Some are just for testing the fit, others are to check that thermal expansion isn't a problem and so on. The actual flight hardware itself is usually tested as well, since it's designed to be repeatedly stressed within certain physical limits. NASA has duplicate rovers in the lab that commands are tested on. Before a mission plan is uploaded, it's tested on the ground system to make sure that, for example, an inspection arm doesn't collide with the body of the rover. Modern rovers like curiosity are reasonably good at self-inspection, since it can take a 360 selfie. The rover is covered with calibration points, for example to measure how much dust is covering things and how far the wheels have worn down. A lot of "testing" is gained through experience. Satellite manufacturers know what designs work based on prior designs. NASA learns a lot every time they put a new rover on Mars. Rover missions (like Curiosity, Spirit/Opportunity, etc) tend to outperform their original specs because the engineering is so conservative. In very rare cases astronauts have done in-space inspections - for example the repairs to Hubble. The ISS is also used as a space-based testing laboratory for hundreds of different projects. (I've worked in a space science laboratory where satellites were routinely tested, and indirectly on rover data).
  - ncol 8y ago
    Sure. I would put that sort of more in the high level engineering than "real-world testing" though. I mean if you are Waymo you can drive around for a year and see what happens. If you are Audi you can still repair some fault after delivery and redesign the next model year. It is when you can't do that you need high levels of quality assurance, integration, fault tolerance etc. If anyone could teleport small objects to Mars it would soon be littered with smart phones in aluminium foil regardless of how harsh the environment is ;)
radiorental 8y ago
I don't work there but I do work at a place that supplies JPL with some of the tools they use to solve the problems you are interested in. https://www.mathworks.com/company/newsletters/articles/bringing-spirit-and-opportunity-to-mars.html https://www.mathworks.com/company/newsletters/articles/bring... If you parse the user community and external repos you will find specific code & models for some of those use cases https://github.com/search?q=matlab+rover https://github.com/search?q=matlab+rover https://www.mathworks.com/matlabcentral/?s_tid=gn_mlc https://www.mathworks.com/matlabcentral/?s_tid=gn_mlc Do note that JPL also uses other tool chains, some open, with similar communities and repos. I'm not as knowledgeable to what extent they use these, ymmv (pun intended) https://github.com/search?q=python+mars+rover https://github.com/search?q=python+mars+rover the fundamental point I would try to convey is that you can learn as they do - through trial and error via simulation.
godelski 8y ago
> dealing with radiation I can at least answer this part of the question. (I have had NASA contracts working on radiation tech, though not in that sector currently) You can use COTS. Just depends how reliable you want it. There's a good interview on EEV blog with one of the XPrize contestants. [0] He talks in detail about how they handle radiation (they basically don't and hope for the best). If you have a mission critical design or are sending to a more extreme environment, like Mars, then you actually have to deal with radiation. Commonly this is done with rad hard chips. Instead of silicon they use sapphire. Sapphire is what is considered rad hard. Downside is that these chips tend to be older and not nearly as powerful as current technology. They will also encase more vital parts in tungsten (especially see Jovian probe designs). Good news is that there's lots of work being done to determine how to make COTS viable (also a LOT cheaper). There's plenty of NASA SBIR/STTR topics on the subject if you want to try your hand at it AND get paid! Note: many abstracts for proposals are public, so you can see what others are attempting. As for LEO and MEO, again it depends on how mission critical you are. Companies like Planet Labs (LEO) don't really concern themselves with radiation (most cube sats don't). They will just reprogram their satellites or take the hit. Typically GEO satellites are very rad hard, because the nature of the mission is to be there a long time and it is extremely expensive to get into that orbit. Typically they go with the tungsten box and rad hard chip design. On the ISS they do a fair amount of research testing shielding. But they are also concerned with debris. So while you may know about aluminum other materials that are good also include Kevlar and Spectra (Ultra High Molecular Weight PE: which is used in grocery bags). People are experimenting with doping these materials, interweaving, different layering conditions, and all sorts of things. Pretty fascinating (and frustrating) work. Hydrogens help get rid of neutrons but you need dense materials for neutrons AND everything else. Note: ISS is in LEO and though you'd get lethal dosages on extended stays with no shielding, rad levels are fairly low. Btw, lots of this work can be done with only some basic understanding of particle physics and can be tested with open source tools like GEANT4[1]! (there are better non-open source tools) Since it is one of these extremely large solution spaces, who knows, you might get lucky! You can play around with different low density materials (like plastics) and high density materials or metals. Goal is light, cheap, and effective. [0] https://www.youtube.com/watch?v=nJLOZDPTp3I https://www.youtube.com/watch?v=nJLOZDPTp3I (3? episodes. There's a few) [1] http://geant4.web.cern.ch/ http://geant4.web.cern.ch/ (this is difficult. I do have some tutorials if anyone is interested) P.S. I can also talk about some of the other stuff, but in less detail since it wasn't my focus. But figured this was long winded enough. Let me know if there is more interest.
froindt 8y ago
While not quite actual rovers, NASA hosts the Robotic Mining Competition every year. [1] The gist of it is they're using a university competition to see lots of prototypes and innovative ideas. They can build a prototype every year or two, but they can see 40-50 ideas and how well they work at RMC. Phil Metzger, a scientist who was at NASA Swamp Works for many years and is now in academia, has attended the competition every year. He also ended up at the top of Hacker News 4 months ago in an unfortunate situation. [2] [1] https://www.nasa.gov/offices/education/centers/kennedy/technology/nasarmc.html https://www.nasa.gov/offices/education/centers/kennedy/techn... [2] https://news.ycombinator.com/item?id=16723099 https://news.ycombinator.com/item?id=16723099
willangley 8y ago
> could you have a remotely-operated lunar rover? Yes. The Soviet Lunokhod program built and flew two successfully in the early 1970s. I don't know the details of how they did this, but it would make sense to use more automation today. A 2.6 second ping time is long enough that pilots who have played modern video games are likely to complain :).
- tomp 8y ago
  I don't think ping is the problem... the problem is "line-of-sight"... Obviously, Earth rotates too fast, so you'd need to use a network of Earth-satellites getting the signal from the moon and transmitting it to the ground station. The other problem, maybe, is how to communicate... Can you have an antenna/laser on the rover itself, or would it need to transmit to a Moon-satellite first (e.g. to save weight on the lander)? How much energy do you need to communicate, can you do it continuously or do you need to "save" energy for a quick burst of radio signals every so often? Is there any other kind of interference (Moon regolith allegedly flies up to 100km above the surface)... These are just simple issues that came to my mind. No idea how relevant they are, and if there are more relevant issues.

by tomp 8y ago

ncol 8y ago

Haven't worked in this field, but here are some episodes discussing the topic: https://www.youtube.com/watch?v=nJLOZDPTp3I https://www.youtube.com/watch?v=nJLOZDPTp3I https://www.youtube.com/watch?v=ADJwChUtdDQ https://www.youtube.com/watch?v=ADJwChUtdDQ https://theamphour.com/334-an-interview-with-gerry-roston/ https://theamphour.com/334-an-interview-with-gerry-roston/ https://theamphour.com/220-an-interview-with-shaun-meehan-doctiloquent-dove-deployer/ https://theamphour.com/220-an-interview-with-shaun-meehan-do... https://theamphour.com/401-an-interview-with-brent-and-bryce-salmi/ https://theamphour.com/401-an-interview-with-brent-and-bryce... https://www.youtube.com/watch?v=FzRP1qdwPKw https://www.youtube.com/watch?v=FzRP1qdwPKw I think what you are talking about is mostly just normal engineering in the sense that the process is similar. What really makes space unique isn't space as such but that there is no real-world (real-space?) testing, no inspections after the fact or do-overs.

radiorental 8y ago
> What really makes space unique isn't space as such but that there is no real-world (real-space?) testing, no inspections after the fact or do-overs. This is becoming less true today as engineering problems become more complex and simulation tools become more capable. Most automotive manufacturers have virtual models of their vehicles in testing long before the first nut meets it's bolt.
joshvm 8y ago
>I think what you are talking about is mostly just normal engineering in the sense that the process is similar. What really makes space unique isn't space as such but that there is no real-world (real-space?) testing, no inspections after the fact or do-overs. This is sort of true? Spacecraft of all types are subject to a battery of physical tests before launch. This includes vacuum testing, thermal cycling and vibration (where many parts fail). There are normally duplicate components produced for different purposes. Some are just for testing the fit, others are to check that thermal expansion isn't a problem and so on. The actual flight hardware itself is usually tested as well, since it's designed to be repeatedly stressed within certain physical limits. NASA has duplicate rovers in the lab that commands are tested on. Before a mission plan is uploaded, it's tested on the ground system to make sure that, for example, an inspection arm doesn't collide with the body of the rover. Modern rovers like curiosity are reasonably good at self-inspection, since it can take a 360 selfie. The rover is covered with calibration points, for example to measure how much dust is covering things and how far the wheels have worn down. A lot of "testing" is gained through experience. Satellite manufacturers know what designs work based on prior designs. NASA learns a lot every time they put a new rover on Mars. Rover missions (like Curiosity, Spirit/Opportunity, etc) tend to outperform their original specs because the engineering is so conservative. In very rare cases astronauts have done in-space inspections - for example the repairs to Hubble. The ISS is also used as a space-based testing laboratory for hundreds of different projects. (I've worked in a space science laboratory where satellites were routinely tested, and indirectly on rover data).
- ncol 8y ago
  Sure. I would put that sort of more in the high level engineering than "real-world testing" though. I mean if you are Waymo you can drive around for a year and see what happens. If you are Audi you can still repair some fault after delivery and redesign the next model year. It is when you can't do that you need high levels of quality assurance, integration, fault tolerance etc. If anyone could teleport small objects to Mars it would soon be littered with smart phones in aluminium foil regardless of how harsh the environment is ;)

radiorental 8y ago

I don't work there but I do work at a place that supplies JPL with some of the tools they use to solve the problems you are interested in. https://www.mathworks.com/company/newsletters/articles/bringing-spirit-and-opportunity-to-mars.html https://www.mathworks.com/company/newsletters/articles/bring... If you parse the user community and external repos you will find specific code & models for some of those use cases https://github.com/search?q=matlab+rover https://github.com/search?q=matlab+rover https://www.mathworks.com/matlabcentral/?s_tid=gn_mlc https://www.mathworks.com/matlabcentral/?s_tid=gn_mlc Do note that JPL also uses other tool chains, some open, with similar communities and repos. I'm not as knowledgeable to what extent they use these, ymmv (pun intended) https://github.com/search?q=python+mars+rover https://github.com/search?q=python+mars+rover the fundamental point I would try to convey is that you can learn as they do - through trial and error via simulation.

godelski 8y ago

> dealing with radiation I can at least answer this part of the question. (I have had NASA contracts working on radiation tech, though not in that sector currently) You can use COTS. Just depends how reliable you want it. There's a good interview on EEV blog with one of the XPrize contestants. [0] He talks in detail about how they handle radiation (they basically don't and hope for the best). If you have a mission critical design or are sending to a more extreme environment, like Mars, then you actually have to deal with radiation. Commonly this is done with rad hard chips. Instead of silicon they use sapphire. Sapphire is what is considered rad hard. Downside is that these chips tend to be older and not nearly as powerful as current technology. They will also encase more vital parts in tungsten (especially see Jovian probe designs). Good news is that there's lots of work being done to determine how to make COTS viable (also a LOT cheaper). There's plenty of NASA SBIR/STTR topics on the subject if you want to try your hand at it AND get paid! Note: many abstracts for proposals are public, so you can see what others are attempting. As for LEO and MEO, again it depends on how mission critical you are. Companies like Planet Labs (LEO) don't really concern themselves with radiation (most cube sats don't). They will just reprogram their satellites or take the hit. Typically GEO satellites are very rad hard, because the nature of the mission is to be there a long time and it is extremely expensive to get into that orbit. Typically they go with the tungsten box and rad hard chip design. On the ISS they do a fair amount of research testing shielding. But they are also concerned with debris. So while you may know about aluminum other materials that are good also include Kevlar and Spectra (Ultra High Molecular Weight PE: which is used in grocery bags). People are experimenting with doping these materials, interweaving, different layering conditions, and all sorts of things. Pretty fascinating (and frustrating) work. Hydrogens help get rid of neutrons but you need dense materials for neutrons AND everything else. Note: ISS is in LEO and though you'd get lethal dosages on extended stays with no shielding, rad levels are fairly low. Btw, lots of this work can be done with only some basic understanding of particle physics and can be tested with open source tools like GEANT4[1]! (there are better non-open source tools) Since it is one of these extremely large solution spaces, who knows, you might get lucky! You can play around with different low density materials (like plastics) and high density materials or metals. Goal is light, cheap, and effective. [0] https://www.youtube.com/watch?v=nJLOZDPTp3I https://www.youtube.com/watch?v=nJLOZDPTp3I (3? episodes. There's a few) [1] http://geant4.web.cern.ch/ http://geant4.web.cern.ch/ (this is difficult. I do have some tutorials if anyone is interested) P.S. I can also talk about some of the other stuff, but in less detail since it wasn't my focus. But figured this was long winded enough. Let me know if there is more interest.

froindt 8y ago

While not quite actual rovers, NASA hosts the Robotic Mining Competition every year. [1] The gist of it is they're using a university competition to see lots of prototypes and innovative ideas. They can build a prototype every year or two, but they can see 40-50 ideas and how well they work at RMC. Phil Metzger, a scientist who was at NASA Swamp Works for many years and is now in academia, has attended the competition every year. He also ended up at the top of Hacker News 4 months ago in an unfortunate situation. [2] [1] https://www.nasa.gov/offices/education/centers/kennedy/technology/nasarmc.html https://www.nasa.gov/offices/education/centers/kennedy/techn... [2] https://news.ycombinator.com/item?id=16723099 https://news.ycombinator.com/item?id=16723099

willangley 8y ago

> could you have a remotely-operated lunar rover? Yes. The Soviet Lunokhod program built and flew two successfully in the early 1970s. I don't know the details of how they did this, but it would make sense to use more automation today. A 2.6 second ping time is long enough that pilots who have played modern video games are likely to complain :).

tomp 8y ago
I don't think ping is the problem... the problem is "line-of-sight"... Obviously, Earth rotates too fast, so you'd need to use a network of Earth-satellites getting the signal from the moon and transmitting it to the ground station. The other problem, maybe, is how to communicate... Can you have an antenna/laser on the rover itself, or would it need to transmit to a Moon-satellite first (e.g. to save weight on the lander)? How much energy do you need to communicate, can you do it continuously or do you need to "save" energy for a quick burst of radio signals every so often? Is there any other kind of interference (Moon regolith allegedly flies up to 100km above the surface)... These are just simple issues that came to my mind. No idea how relevant they are, and if there are more relevant issues.