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> As well as searching for signs of life, Perseverance's other key objective is to select and package rock samples that can be brought back to Earth laboratorie

by elihu 6y ago

> As well as searching for signs of life, Perseverance's other key objective is to select and package rock samples that can be brought back to Earth laboratories by later missions. That seems like a strange thing to have as a top priority. I would have thought the main thing was to examine the rocks there without having to bring them back to Earth. And later on, if you have a return-trip mission, you could probably just grab some convenient rocks then (though I suppose Perseverance will have a lot time to pick out only the best, most interesting rocks). This also implies that a return-trip mission, if it happens, will be obligated to go to Perseverance's last location or else collecting the rocks was a waste. Which by then we might have more interesting places we'd rather land. Are there any unmanned Earth-to-Mars-to-Earth missions planned, or is the current thinking that we'll be sending people there on the first return-trip mission?

eru 6y ago
Some people are also thinking about making the first manned missions one-way.
avhon1 6y ago
The current plan is for a launch in 2026 to send a NASA-designed rocket, and a rover and an orbiter designed by ESA, to Mars. The rover will collect Perseverance's sample tubes and place them in the rocket, which will carry the tubes into Mars orbit. The orbiter will rendezvous, collect the sample tubes, and carry them back to Earth, landing in Utah in 2031. https://spaceflightnow.com/2020/04/20/nasa-narrows-design-for-rocket-to-launch-samples-off-of-mars/ https://spaceflightnow.com/2020/04/20/nasa-narrows-design-fo... Edit: to your other points, I've thought of some justifications for this architecture: * The sample return mission will have very limited payload capacity, so the samples should be chosen on the basis of potential scientific value, and selected from a large land area. This can probably best be done with a multi-year rover mission equipped with the best scientific instruments and locomotion available. * Perseverance's scientific instruments are useful for studying rocks that won't be sampled, so spending weeks or months ferrying samples to a return vehicle would be a sub-optimal use of its very valuable time. * Mechanically interfacing (to transfer samples) with an orbital solid-fuel rocket is probably somewhat dangerous, so it's best for Perseverance if there's a less-valuable robot to do that. * The return vehicle will probably be limited in where it can land, because it will have to land on ground that is suitable to launch from. It is unlikely to be landed anywhere close to a bunch of interesting rocks and formations. * Science instruments, and the manipulators to use them, are heavy, power-hungry, and fragile. If the sample-collection rover doesn't have any, then it can be better-specialized for the task: faster, less fragile, able to traverse softer or more rugged ground. Traveling many tens of kilometers to collect samples may not be nearly as difficult for it as for any previous, science-burdened rover.
bryananderson 6y ago
The first priority is to examine the rocks there, and Perseverance is stuffed to the gills with scientific instruments to do just that. But there's no way JPL can squeeze every kind of instrument from every kind of lab on Earth into one rover. If we want to get the most out of our trip to Jezero, we need a way to bring some rocks back here. And yes that does mean a second trip to the same place. We could send human geologists to bring the samples back (though they could obviously pick up rocks themselves), but sending humans to Mars is both more expensive and more uncertain (it's been on the agenda many times but is always vulnerable to budget cuts due to the price tag and long duration of the program). The only other way to do it is to send a robotic sample return mission. Why do it as two missions to the same place instead of one? Because a fully kitted-out scientific rover and an ascent stage together would be very heavy, requiring a larger rocket and probably a different entry, descent, and landing (EDL) mode. Mars EDL is hard: gravity too high for an easy powered descent like the Moon, atmosphere too thin for an easy aerobraked descent like Earth. The current "sky crane" EDL mode does not scale well to heavier vehicles. So we can't just send an ascent stage with Perseverance, and a near-future there-and-back-again mission couldn't feature a rover as capable as Perseverance. The best compromise is to find the most interesting samples with a top-of-the-line scientific rover, then send the ascent stage to get them later. And yes, this uncrewed return mission is planned by NASA/JPL and ESA [1]. The current concept involves two launches: one sends a lander with an ascent stage (and possibly a small rover to fetch the samples, or Perseverance could do it--it depends how soon the ascent mission gets there) and the second sends an Earth return stage to bring the samples the rest of the way home. [1] https://www.nasa.gov/press-release/nasa-moves-forward-with-campaign-to-return-mars-samples-to-earth https://www.nasa.gov/press-release/nasa-moves-forward-with-c...

by elihu 6y ago

eru 6y ago

Some people are also thinking about making the first manned missions one-way.

avhon1 6y ago

The current plan is for a launch in 2026 to send a NASA-designed rocket, and a rover and an orbiter designed by ESA, to Mars. The rover will collect Perseverance's sample tubes and place them in the rocket, which will carry the tubes into Mars orbit. The orbiter will rendezvous, collect the sample tubes, and carry them back to Earth, landing in Utah in 2031. https://spaceflightnow.com/2020/04/20/nasa-narrows-design-for-rocket-to-launch-samples-off-of-mars/ https://spaceflightnow.com/2020/04/20/nasa-narrows-design-fo... Edit: to your other points, I've thought of some justifications for this architecture: * The sample return mission will have very limited payload capacity, so the samples should be chosen on the basis of potential scientific value, and selected from a large land area. This can probably best be done with a multi-year rover mission equipped with the best scientific instruments and locomotion available. * Perseverance's scientific instruments are useful for studying rocks that won't be sampled, so spending weeks or months ferrying samples to a return vehicle would be a sub-optimal use of its very valuable time. * Mechanically interfacing (to transfer samples) with an orbital solid-fuel rocket is probably somewhat dangerous, so it's best for Perseverance if there's a less-valuable robot to do that. * The return vehicle will probably be limited in where it can land, because it will have to land on ground that is suitable to launch from. It is unlikely to be landed anywhere close to a bunch of interesting rocks and formations. * Science instruments, and the manipulators to use them, are heavy, power-hungry, and fragile. If the sample-collection rover doesn't have any, then it can be better-specialized for the task: faster, less fragile, able to traverse softer or more rugged ground. Traveling many tens of kilometers to collect samples may not be nearly as difficult for it as for any previous, science-burdened rover.

bryananderson 6y ago

The first priority is to examine the rocks there, and Perseverance is stuffed to the gills with scientific instruments to do just that. But there's no way JPL can squeeze every kind of instrument from every kind of lab on Earth into one rover. If we want to get the most out of our trip to Jezero, we need a way to bring some rocks back here. And yes that does mean a second trip to the same place. We could send human geologists to bring the samples back (though they could obviously pick up rocks themselves), but sending humans to Mars is both more expensive and more uncertain (it's been on the agenda many times but is always vulnerable to budget cuts due to the price tag and long duration of the program). The only other way to do it is to send a robotic sample return mission. Why do it as two missions to the same place instead of one? Because a fully kitted-out scientific rover and an ascent stage together would be very heavy, requiring a larger rocket and probably a different entry, descent, and landing (EDL) mode. Mars EDL is hard: gravity too high for an easy powered descent like the Moon, atmosphere too thin for an easy aerobraked descent like Earth. The current "sky crane" EDL mode does not scale well to heavier vehicles. So we can't just send an ascent stage with Perseverance, and a near-future there-and-back-again mission couldn't feature a rover as capable as Perseverance. The best compromise is to find the most interesting samples with a top-of-the-line scientific rover, then send the ascent stage to get them later. And yes, this uncrewed return mission is planned by NASA/JPL and ESA [1]. The current concept involves two launches: one sends a lander with an ascent stage (and possibly a small rover to fetch the samples, or Perseverance could do it--it depends how soon the ascent mission gets there) and the second sends an Earth return stage to bring the samples the rest of the way home. [1] https://www.nasa.gov/press-release/nasa-moves-forward-with-campaign-to-return-mars-samples-to-earth https://www.nasa.gov/press-release/nasa-moves-forward-with-c...