3 ms·

>All the other details for Mars can be done with variants of what already exists or will fly shortly (commercial crew vehicles or even Soyuz, ISS modules for a

>All the other details for Mars can be done with variants of what already exists or will fly shortly (commercial crew vehicles or even Soyuz, ISS modules for a transfer craft, launch vehicles like the EELVs used by the military or Falcon 9 or Falcon Heavy, in-orbit docking and propellant transfer which is commonly used on the Space Station, etc). I'll grant you a lot of that, but do you really think re-using ISS modules for transfer craft would be remotely feasible? The vastly different radiation regimes between LEO and interplanetary space make me doubt that this would work.

Robotbeat 9y ago
Yes it is feasible. The radiation regimes are not vastly different. They're within roughly a factor of two of one another. And since the transit time is about half a year, and we've had multiple people experience ~year-long trips in orbit at a time, I think we're well within our existing knowledge to say they'd do fine radiation-wise, though perhaps with a slightly higher risk than usual. Still better than being a smoker. That is not at all the showstopper. If you choose to remain in orbit around Mars instead of landing, however, you'll be exposed to a higher dose. Mars' surface has a level of radiation that's below that of ISS plus contains plenty of material for shielding your habitat. Therefore, the lander helps address the radiation problem as well by getting you down to the surface for most of the mission's duration (instead of doing initial missions in Mars orbit only due to lack of money for a Mars lander as is the current NASA plan). (Using the ISS spare pool is only one possible solution, by the way, and not likely to be the most optimum.)
- CydeWeys 9y ago
  There's also the issue of coronal mass ejections (though CMEs pointing right at us are admittedly rare, so maybe you just eat the risk). They will absolutely fry anything in their path, but take 1-3 days to reach the Earth from the Sun, which is long enough to bring any astronauts on the ISS back down to Earth. I believe there are contingency plans for this; there is always a crew return vehicle attached to the station ready to go for example. If that happens while you're on the way to Mars, though, you're all fried.
- Robotbeat 9y ago
  By the way, radiation from coronal mass ejections and associated solar particle events (SPEs) is much easier to shield than radiation from galactic cosmic rays (GCRs are the primary concern for long-term astronaut exposure on Mars). Even the thin skin of the spacecraft is enough to reduce the SPE dosage to non-acutely-lethal levels, and rearranging the provisions (food and water) around a central location is sufficient to reduce the dosage due to solar particle events to a manageable level. On board ISS, the crew return vehicles are not for ditching due to an SPE. Such radiation events travel fast enough that you'd likely be stuck in the crew return vehicle when it hit. The Station itself provides much better shielding from such events, and ditching in a hurry (landing somewhere random in the ocean) would be much more dangerous than sheltering in place.

Robotbeat 9y ago

Yes it is feasible. The radiation regimes are not vastly different. They're within roughly a factor of two of one another. And since the transit time is about half a year, and we've had multiple people experience ~year-long trips in orbit at a time, I think we're well within our existing knowledge to say they'd do fine radiation-wise, though perhaps with a slightly higher risk than usual. Still better than being a smoker. That is not at all the showstopper. If you choose to remain in orbit around Mars instead of landing, however, you'll be exposed to a higher dose. Mars' surface has a level of radiation that's below that of ISS plus contains plenty of material for shielding your habitat. Therefore, the lander helps address the radiation problem as well by getting you down to the surface for most of the mission's duration (instead of doing initial missions in Mars orbit only due to lack of money for a Mars lander as is the current NASA plan). (Using the ISS spare pool is only one possible solution, by the way, and not likely to be the most optimum.)

CydeWeys 9y ago
There's also the issue of coronal mass ejections (though CMEs pointing right at us are admittedly rare, so maybe you just eat the risk). They will absolutely fry anything in their path, but take 1-3 days to reach the Earth from the Sun, which is long enough to bring any astronauts on the ISS back down to Earth. I believe there are contingency plans for this; there is always a crew return vehicle attached to the station ready to go for example. If that happens while you're on the way to Mars, though, you're all fried.
Robotbeat 9y ago
By the way, radiation from coronal mass ejections and associated solar particle events (SPEs) is much easier to shield than radiation from galactic cosmic rays (GCRs are the primary concern for long-term astronaut exposure on Mars). Even the thin skin of the spacecraft is enough to reduce the SPE dosage to non-acutely-lethal levels, and rearranging the provisions (food and water) around a central location is sufficient to reduce the dosage due to solar particle events to a manageable level. On board ISS, the crew return vehicles are not for ditching due to an SPE. Such radiation events travel fast enough that you'd likely be stuck in the crew return vehicle when it hit. The Station itself provides much better shielding from such events, and ditching in a hurry (landing somewhere random in the ocean) would be much more dangerous than sheltering in place.