Http://www.planetary.org/blogs/jason-davis/2018/20180610-meet-mmx.html

Meet MMX, Japan’s sample return mission to Phobos

You may have heard that both NASA and China have plans to return samples from Mars. NASA’s Mars 2020 rover will curate a cache of samples for future retrieval, while China is kicking off their Mars ambitions in 2020 with an all-in-one orbiter, lander and rover.

But did you know there’s also a Phobos sample mission in the works? Meet Japan’s Mars Moons eXploration mission, also known as MMX, which will launch in 2024. MMX will study both Phobos and Deimos and collect a sample of Phobos for return to Earth in 2029.

The goal of MMX is to try and figure out where Phobos and Deimos came from. Did something big hit Mars and knock off a bunch of material, and that material lumped together to form the moons? Or are they captured asteroids of some sort? Surprisingly, we have no idea.

If MMX finds lots of volatiles—lighter materials like water, carbon, and sulfur—then this supports the theory Phobos and Deimos are captured, primordial objects. If the moons are bone-dry, they may have come from Mars, and could be a time capsule for early Mars conditions.

mollwollfumble said:

Http://www.planetary.org/blogs/jason-davis/2018/20180610-meet-mmx.html

Meet MMX, Japan’s sample return mission to Phobos

You may have heard that both NASA and China have plans to return samples from Mars. NASA’s Mars 2020 rover will curate a cache of samples for future retrieval, while China is kicking off their Mars ambitions in 2020 with an all-in-one orbiter, lander and rover.

But did you know there’s also a Phobos sample mission in the works? Meet Japan’s Mars Moons eXploration mission, also known as MMX, which will launch in 2024. MMX will study both Phobos and Deimos and collect a sample of Phobos for return to Earth in 2029.

The goal of MMX is to try and figure out where Phobos and Deimos came from. Did something big hit Mars and knock off a bunch of material, and that material lumped together to form the moons? Or are they captured asteroids of some sort? Surprisingly, we have no idea.

If MMX finds lots of volatiles—lighter materials like water, carbon, and sulfur—then this supports the theory Phobos and Deimos are captured, primordial objects. If the moons are bone-dry, they may have come from Mars, and could be a time capsule for early Mars conditions.

Phobos has a notorious record for failing spacecraft. The low densities of phobos and deimos sparked speculation very early on. Russia has sent at least three failed missions to Phobos. They attempted a sample return from Phobos and failed.

There has still been no significant sample return from outer space (beyond a few grains) since 1976, from Luna 24.

mollwollfumble said:

There has still been no significant sample return from outer space (beyond a few grains) since 1976, from Luna 24.

That’s surprising.

How does the energy requirement to get back from Phobos compare with a return from the Moon?

The Rev Dodgson said:

mollwollfumble said:

There has still been no significant sample return from outer space (beyond a few grains) since 1976, from Luna 24.

That’s surprising.

How does the energy requirement to get back from Phobos compare with a return from the Moon?

I could answer that. Let me check “https://en.m.wikipedia.org/wiki/Delta-v_budget”.

0.5 Phobos surface to Phobos transfer orbit
0.3 Phobos transfer orbit to Diemos transfer orbit
0.2 Diemos transfer orbit to Mars capture orbit
0.9 Mars capture orbit to Mars transfer orbit
4.3 Mars transfer orbit to LEO

Compare that with sample return from the Moon’s surface.

1.87 Moons surface to Low Lunar Orbit
1.31 Low Lunar Orbit to Low Earth Orbit.

The answer will therefore depend on how much of that energy transfer from Mars Transfer Orbit to Earth can be handled by aerobraking.

If none then the comparison is:
3.18 return from Moon vs 6.2 return from Phobos.

If all then the comparison is:
1.87 return from Moon vs 1.9 return from Phobos.
Virtually identical.

mollwollfumble said:

The Rev Dodgson said:

mollwollfumble said:

There has still been no significant sample return from outer space (beyond a few grains) since 1976, from Luna 24.

That’s surprising.

How does the energy requirement to get back from Phobos compare with a return from the Moon?

I could answer that. Let me check “https://en.m.wikipedia.org/wiki/Delta-v_budget”.

0.5 Phobos surface to Phobos transfer orbit
0.3 Phobos transfer orbit to Diemos transfer orbit
0.2 Diemos transfer orbit to Mars capture orbit
0.9 Mars capture orbit to Mars transfer orbit
4.3 Mars transfer orbit to LEO

Compare that with sample return from the Moon’s surface.

1.87 Moons surface to Low Lunar Orbit
1.31 Low Lunar Orbit to Low Earth Orbit.

The answer will therefore depend on how much of that energy transfer from Mars Transfer Orbit to Earth can be handled by aerobraking.

If none then the comparison is:
3.18 return from Moon vs 6.2 return from Phobos.

If all then the comparison is:
1.87 return from Moon vs 1.9 return from Phobos.
Virtually identical.

Actually, if all, then Moon sample return wuold be >> 1.87 because no data is given for Low Lunar Orbit to Lunar Transfer Orbit.

So if all the energy transfer is absorbed in aerobraking then it actually takes less energy to return a sample from Phobos that from the Moon.