Mars Sample Return Options

[stevesliva]

Is it just because, well you know, its Mars? Is it the possible life thing? Is it programmatic inertia?

Presumably a lot can be learned, yadda yadda.

But yeah, it's Mars, it's the next big obvious thing to do, and NASA et al should do it first after the two big rovers.

I do sort of feel for whomever was calling for innovative mission designs with proven technologies, though.

[StargazeInWonder]

Mars Sample Return is a huge budget item that has seen its funding rise and fall, which puts a block on other priorities, so that alone makes it news, while a possible mission that has never gotten authorization is almost by definition not news (or very minor news).

An outer planet orbiter will also take years to produce any results in the best case, and I don't think the public imagination would see it as a potential ground-shaker until and unless it found something surprising.

If you polled people on the street, I doubt that many know that missions are on the way to the Mercury, Venus (planned), and jovian systems. But Mars Sample Return would definitely occupy some news cycles, even before the first pebble got under a microscope.

[mcaplinger]

https://spacenews.com/practical-approach-ma...return-mission/

Worth a read, but I'm skeptical of Zubrin's 50-kg total mass Earth return vehicle. And even if the delta V numbers work out in the abstract, he presupposes all the planetary protection requirements can be made to go away.

[StargazeInWonder]

Interesting and unexpected bogeyman that he identifies and eliminates. Agreed that it is probably not going to be so simple to just wish that requirement away.

I wonder if – if – that is such a large part of the cost, if it could be reduced by moving the point of defense from Mars to Earth: Allow a no-planetary-protection return capsule to leave Mars, come to Earth orbit, and then get protected while in Earth orbit. That still sounds expensive and Rube Goldberg-ish, but would seem to be sub-billions.

Zubrin loves to cut the Gordian Knot. But this particular knot is there for a reason.

[mcaplinger]

Allow a no-planetary-protection return capsule to leave Mars, come to Earth orbit, and then get protected while in Earth orbit.

No, I don't think this helps. Getting into Earth orbit is either risky (aerocapture) or very expensive in terms of delta V. Unless there is some exotic propulsion system or some complex chaotic trajectory. And once you had it in Earth orbit, then what?

His ISRU solution handwaves the difficulty and complexity of making and storing the propellant, but at least it has slightly better mass margins.

[Explorer1]

The entire motivation of the MSR program is the study of samples on Earth, anyway. Instruments in Earth orbit are only a slight improvement from those we bring to the surface of Mars.
Part of the issue is that the entry capsule has no parachute, so there's more chance of a breach when impacting at terminal velocity. But the parachute was removed due to mass requirements, as I recall, so adding it back would be counterproductive.
And the only way to decisively remove PP requirements would be to prove a negative, which is essentially impossible (and this forum has rule 1.3 anyway).

[StargazeInWonder]

The entire motivation of the MSR program is the study of samples on Earth, anyway. Instruments in Earth orbit are only a slight improvement from those we bring to the surface of Mars.

My notion was that the protection could occur in Earth orbit, then the protected samples could be brought to the ground. Eg, put the dirty capsule into a casing, the outside of which never touches any martian stuff. Then land.

As mcaplinger notes, this has more than one problem of its own, one of which is risk.

Cassini led to protests because Cassini had plutonium onboard. It's hard to put a price tag or perform rational analysis of risk factors in the public consciousness. But when the cost of the program is $11 billion and a risk factor in the public consciousness is part of that cost, possible cost savings involve manipulating the consciousness of risk, which is not the same thing as risk itself. Zubrin seems to wish the whole thing away. With Cassini, NASA weathered the protests. Note that one of the vocal Cassini protesters was Michio Kaku, who is one of the most prominent publicizers of science and technology.

http://www.cnn.com/TECH/9710/04/cassini/

Planetary protection doesn't have any definite equations governing the risks that it is trying to address. It seems to be a PR exercise with engineering components.

[mcaplinger]

Planetary protection doesn't have any definite equations governing the risks that it is trying to address. It seems to be a PR exercise with engineering components.

Semi-serious proposals have been made for Earth-orbiting labs to quarantine and examine returned samples. https://www.hou.usra.edu/meetings/deepspace2018/pdf/3189.pdf is a recent example that references the early-80s Antaeus Report https://ntrs.nasa.gov/citations/19820012351

This concept sort of showed up in the (unwatchable IMHO) movie LIFE ( https://en.wikipedia.org/wiki/Life_(2017_film) )

Of course, these would all be staggeringly expensive.

I suspect Zubrin is right and planetary protection from Mars is probably not needed. But it's one of those low-probability/high-consequence things that few people would be willing to risk if it was up to them. And Michael Crichton just did too darn good a job when he wrote https://en.wikipedia.org/wiki/The_Andromeda_Strain

[StargazeInWonder]

Very helpful links, thanks! And Crichton is the inevitable reference.

Japan proposes the return of some Phobos samples (probably) before MSR. This seems to raise and dispel similar risks since the research expects martian material to exist without the same strong filters as such martian meteorites as make it to Earth. Where there is no equation is in where on the continuum we need to worry and where we don't.

Martian meteorites (already here)
Martian material in Phobos samples
Martian material in the Perseverance tubes (no protection)
Martian material in the Perseverance tubes (some protection)
Martian material in the Perseverance tubes (the most imaginable protection – still breachable by some level of mishap)

Nuclear reactor safety has included such considerations as what would happen if an airplane accident happened to breach the containment. That sounds like an unreasonable level of concern, and yet it has been exceeded on at least two occasions.