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#1 2013-12-17 17:36:30

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
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Sample Return with In-Situ Propellant Production

Over in the other thread, we were talking about the possibility for a sample return mission that would serve, primarily, as a technological testbed for In-Situ Resource Utilization technologies.  I propose that in this thread we should try to design a mission aimed at testing them in the context of a sample return mission.

I propose a few guidelines:

1) The mission should not cost more than $1 billion
2) The probe will use In-Situ Propellant Production technologies to produce Methane and Oxygen fuels from the atmosphere given an onboard source of Hydrogen
     2a) Other technologies may also be used to experiment (e.g. using local water resources to produce Hydrogen in addition to Hydrogen brought from Earth) but should not be vital
3) The probe will return 250 g of material to Earth taken from various (nearby) sources utilizing some kind of mobile system [e.g a small rover].  This mobile system should have a range of at least 100 m, which will allow for a good variety of interesting samples to be taken from a very local area.
4) The probe should be designed to be as simple as possible in order to maximize the chances of success

I'd love to see what we come up with!  I have some ideas of my own which I'll flesh out in the next couple of days.


-Josh

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#2 2013-12-17 21:05:24

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,729

Re: Sample Return with In-Situ Propellant Production

The launch return mission cycle time is assumed to be long stay on the surface to allow for the fuels production. That allows for the rover to be solar powered. I would design the lander with a car port in the lander to give the rover an extra boost of power and shelter from the mars dust storms.

So what type of sensors for the rover would be one feature that needs to be nailed down for the collection process. The lander could be RTG powered to allow for the power drain needed for the electrolysis and atmospheric pumps.

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#3 2013-12-17 21:39:57

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Sample Return with In-Situ Propellant Production

I was thinking solar PV power would be the better choice; It certainly seems to have worked fairly well for the rovers, and if the system were designed so that dry, excess CO was blown out over the solar panels that would go a long way towards ensuring that they remained clear for the duration of the mission.

I envision 250 g of samples to mean at least 100-200 different kinds of sample.  This means that we don't need to be too particular about what we sample, but can really afford to take a bit of everything.  I would say a visible light camera, something that can sense water, perhaps a magnetometer, perhaps a spectroscope?  This is a more comprehensive imaging suite than the pathfinder rover had, and is probably more comprehensive than is really necessary.

I would agree with the long stay mission-- the 30 days for a short stay is simply too short!

But then again, not much fuel is really needed.  If the payload to LEO from Mars is 10 kg, Vex is 6 km/s, and exhaust velocity is 3.5 km/s, the mass ratio is 5.5.  Surely 2-3 kg of Methlox per day isn't really all that much?


-Josh

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#4 2013-12-20 01:58:45

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Sample Return with In-Situ Propellant Production

Well, I have a final tomorrow morning, but I can't sleep.  In a time like this, there is only one logical course of action, which is to design a Martian sample return mission that incorporates a testbed for ISRU technologies smile

Looking into orbital trajectories, I've come to find that they're obscenely complicated.  Take a look at this paper, for example.  I would note that this serves as a nice independent verification of the Inspiration Mars trajectory, from over a decade ago.  My point is that I don't know what the best orbit to use is.

I want a shorter stay time because a longer stay gives more time for components to fail, and for cryogenics to evaporate.  Realistically we only need a 30-50 day ground time, since collecting samples and producing rather meager amounts of rocket fuel isn't something that should take all that long.

I like the conjunction class missions for this purpose, actually, but I'm not sure how often launch windows come about.  Does anyone know on that one?


-Josh

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#5 2013-12-20 22:05:15

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,729

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#6 2013-12-21 15:50:31

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,729

Re: Sample Return with In-Situ Propellant Production

JoshNH4H are you thinking that a capsule simular to Stardust/Genesis would be adequate for the task of bringing the samples back to Earth in?

http://www.cs.odu.edu/~mln/ltrs-pdfs/NA … sc-pnd.pdf

Would the samples from mars be transferred into an awaiting orbiter for return to earth?

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#7 2013-12-22 19:51:15

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Sample Return with In-Situ Propellant Production

Spacenut-

My question is whether those missions require a gravitational assist by Venus.  I ask because, if they do, that severely limits the usefulness of that trajectory as a component of a technology demonstrator.

And I'm thinking of something a bit larger than the Stardust capsule, but realistically not all that much larger.  250 g of material is really not very much, at all.

Edit:

Actually, looking at the size of that capsule I bet we wouldn't need to go that large, since we wouldn't have to try to capture any cometary dust.  In fact we would need less than one liter of cargospace.


-Josh

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#8 2013-12-22 22:20:08

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,729

Re: Sample Return with In-Situ Propellant Production

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#9 2013-12-23 20:55:31

JoshNH4H
Member
From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Sample Return with In-Situ Propellant Production

I think this is something for which I'd have to pull out Matlab and do my own simulations.


-Josh

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#10 2017-01-14 12:05:55

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,729

Re: Sample Return with In-Situ Propellant Production

After we find water or have the power and equipment to move soils we will be wanting to make sure this can happen to allow for a crew to survive.

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