Author Topic: A more efficient mars architecture  (Read 14807 times)

Offline Kaputnik

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Re: A more efficient mars architecture
« Reply #20 on: 02/20/2012 02:35 pm »
I definitely support the Mars Direct plan myself, although I would want to use existing commercial rockets rather than waiting for a new government rocket, and I would use solar rather than nuclear.

But no 'commercial' rockets can lift bulky/wide enough payloads to support Mars Direct. You really need SDLV to reach that kind of fairing size.

Quote
Like Robotbeat, I'm somebody that one would expect to support nuclear power -- I'm a former US Navy submariner -- but it seems like solar is superior in some ways. For example, if you use solar thermal (mirrors concentrate solar power onto a heat engine), it is all very simple mechanical parts, and could, in theory, be fixed if it doesn't work. Solar photovoltaic has few if any moving parts, so it should theoretically be more reliable.
One of the core principles of Mars Direct was that the ERV could sent on ahead and tank up in advance of the manned landing. It's far easier to envisage this happening with nuclear power which is self-contained. A vast solar array would be 'interesting' to deploy robotically/automatically.
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Offline Kaputnik

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Re: A more efficient mars architecture
« Reply #21 on: 02/20/2012 02:36 pm »
Oh, and another thing- the OP has never answered my question about single-pass MOI using NEP.
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Offline A_M_Swallow

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Re: A more efficient mars architecture
« Reply #22 on: 02/20/2012 03:33 pm »

One of the core principles of Mars Direct was that the ERV could sent on ahead and tank up in advance of the manned landing. It's far easier to envisage this happening with nuclear power which is self-contained. A vast solar array would be 'interesting' to deploy robotically/automatically.

Getting a wheeled version of Robonaut to unload a dummy lander and set up a solar array will be an interesting exercise for the Desert RATS people.

Offline spectre9

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Re: A more efficient mars architecture
« Reply #23 on: 02/21/2012 12:05 am »
NASA will never build the Mars Direct lander ERV.

It's just too big.

They prefer to build a smaller MAV that will dock to an ERV waiting in orbit which will most likely be Orion/Deep Space Hab.

I think they will use ISRU for the MAV powered by nuclear energy.

Just not sure it's going to be launching out of some funky horizontal lander.


Offline Warren Platts

Re: A more efficient mars architecture
« Reply #24 on: 02/21/2012 12:40 pm »
Mars Direct is the epitome of an extremely wasteful, inefficient Mars architecture! Huge IMLEO and what comes back? One tiny capsule.

The OP wants to minimize the development of new technologies. NEP probably wouldn't work (cf. work on the concept by Kirk Sorensen described at selenianboondocks.com).

The obvious solution would be to use the "abundant chemical" (Abd chem) paradigm where the abundant chemical propellant comes from Lunar ISRU. This would allow a number of things:

1. Fully reusable/fully propulsive MTV/ERV single vehicle.

2. Martian ISRU would not have to be on the critical path.

3. Lunar landers could be upgraded to fully propulsive Mars landers.

4. Exotic technologies like NEP, NTR, SEP, aerocapture, robotic ISRU wouldn't have to be developed, although an SEP tug to move Mars propellant depots from L2 to LMO would certainly be a nice-to-have but not strictly necessary.

5. Development costs in general for Mars would be limited mainly to the development of the reusable MTV; the propellant tanks of which would simply be discarded ACES-121 propellant tanks left over from the construction of the Lunar base. 
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Offline alexterrell

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Re: A more efficient mars architecture
« Reply #25 on: 03/07/2012 08:15 am »
Might it not make more sense to use the abundant chemical resources of Phobos, which in delta V terms is closer to Earth Moon L1 than the lunar surface.

Sadly, Phobos Grunt won't tell us exactly what Phobos is made of and how we can process it.

But a general architecture could be:
1. SEP to launch fuel, cargo and a Mars Transfer Vehicle to Earth Moon L1. The fuel could be Kerosene or methane/Lox for long term storage.
2. Orion to deliver crew to L1
3. Chemical stage to Mars, with aerocapture to Phobos orbit.
4. Base with ISRU in (not quite the same as "on") Phobos.
5. Crew return with chemical propulsion and aerocapture - probably to L1 for reuse of MTV.

The Mars Lander is the most complex, risky and expensive piece of equipment. This could be deferred till Phobos is up and running. If a reusable lander is feasible it would be made small (easier entry) and designed to shuttle between Phobos and Mars Surface.

This was covered here.

http://forum.nasaspaceflight.com/index.php?topic=19308.new;topicseen#new
 
Personally I find Phobos more "useful" than Mars, but for public consumption it can be thought of as a stepping stone to Mars.
« Last Edit: 03/07/2012 08:21 am by alexterrell »

Offline go4mars

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Re: A more efficient mars architecture
« Reply #26 on: 03/07/2012 12:53 pm »
2. Martian ISRU would not have to be on the critical path.
I think Martian ISRU is a lot lower risk and more straight-forward than Lunar ISRU.  Feel free to try to convince me otherwise.  I am open to contrary ideas. 

3. Lunar landers could be upgraded to fully propulsive Mars landers.
Really?  My impression is that the conditions are so different that two nearly completely different systems would be required.  Care to elaborate? 
« Last Edit: 03/07/2012 12:54 pm by go4mars »
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Offline alexterrell

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Re: A more efficient mars architecture
« Reply #27 on: 03/07/2012 03:01 pm »
2. Martian ISRU would not have to be on the critical path.
I think Martian ISRU is a lot lower risk and more straight-forward than Lunar ISRU.  Feel free to try to convince me otherwise.  I am open to contrary ideas. 

Depends if you want hydrogen. There's been discussion here about a Carbon monoxide plus oxygen rocket which would be easy to ISRU (is that a verb?) on Mars and sufficient for escape velocity.

But once you have the capability for ISRU, you want to do it in as many places as possible. Mars surface derived propellants are not much help at L1, and lunar derived propellants are not much help on Mars surface.

Offline QuantumG

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Re: A more efficient mars architecture
« Reply #28 on: 03/07/2012 04:37 pm »
But once you have the capability for ISRU, you want to do it in as many places as possible. Mars surface derived propellants are not much help at L1,

Uhhh.. why? Last I checked, the prospects of making propellant on Mars were a lot better than Lunar ISRU.. so why wouldn't one return propellant from Mars to L1 for a subsequent mission? Especially in a fully reusable architecture.
Human spaceflight is basically just LARPing now.

Offline A_M_Swallow

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Re: A more efficient mars architecture
« Reply #29 on: 03/07/2012 05:10 pm »
But once you have the capability for ISRU, you want to do it in as many places as possible. Mars surface derived propellants are not much help at L1,

Uhhh.. why? Last I checked, the prospects of making propellant on Mars were a lot better than Lunar ISRU.. so why wouldn't one return propellant from Mars to L1 for a subsequent mission? Especially in a fully reusable architecture.


Mars ISRU propellant at EML-1 means that the transfer vehicles and the landers use the same fuel.  Currently the proposed designs have hydrogen fuelled transfer vehicles and carbon compounds (methane, CO) for landers.

(I am assuming the L1 meant EML-1 rather than SML1 (Sun-Mars Lagrange point 1).)

Offline Robotbeat

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Re: A more efficient mars architecture
« Reply #30 on: 03/07/2012 05:36 pm »
But once you have the capability for ISRU, you want to do it in as many places as possible. Mars surface derived propellants are not much help at L1,

Uhhh.. why? Last I checked, the prospects of making propellant on Mars were a lot better than Lunar ISRU.. so why wouldn't one return propellant from Mars to L1 for a subsequent mission? Especially in a fully reusable architecture.

Because ISRU on Earth is a lot easier unless you're talking about atmospheric skimming.
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Offline QuantumG

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Re: A more efficient mars architecture
« Reply #31 on: 03/07/2012 05:41 pm »
Because ISRU on Earth is a lot easier unless you're talking about atmospheric skimming.

Can't say I disagree.
Human spaceflight is basically just LARPing now.

Offline alexterrell

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Re: A more efficient mars architecture
« Reply #32 on: 03/07/2012 06:06 pm »
But once you have the capability for ISRU, you want to do it in as many places as possible. Mars surface derived propellants are not much help at L1,

Uhhh.. why? Last I checked, the prospects of making propellant on Mars were a lot better than Lunar ISRU.. so why wouldn't one return propellant from Mars to L1 for a subsequent mission? Especially in a fully reusable architecture.

Because of the cost of launching your propellant from Mars surface, and transporting it to Earth Moon L1, which also means keeping it liquid for 8 months.

And Mars surface is not so good for hydrogen, so either you need to bring that from Earth system, or you need to use CO + O2, which may have a very large mass fraction for Mars Surface > Mars Orbit > Earth Intercept > EM-L1 > Mars Intercept > Mars Surface (about 9km/s assuming aerocapture).

Energetically speaking, Phobos or Deimos are the best places for a filling station. Then Mars ISRU only needs to support the 4.1km/s to reach Mars orbit.

Offline marcellino

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Re: A more efficient mars architecture
« Reply #33 on: 03/10/2012 03:08 pm »
hi floks, and is anybody thinking about BIOPONICA system to make crew on Mars surface little more independent?

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