LSAM Particulars

#20 by hyper_snyper on 29 May, 2006 23:38
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nacnud - 29/5/2006 7:20 PM The big step you are missing is, what transfer vehicle?
I know, it was just a hypothetical question.
#21 by mong' on 30 May, 2006 01:03
to be honest I don't really see the point of stopping by the martian moons.
one advantage of Mars is that it has an atmosphere, so you can aerobrake to surface/orbit. no need to carry any fuel for orbit insertion or descent
by landing on phobos or deimos you sort of zapp that advantage, and you can forget ISRU for propellant production.

not to mention that it adds unnecessary complications, even if you use aerobraking to put yourself directly in an orbit that intercetpts either moon

but to answer your question, yes I think you could use the LSAM, since it's meant to be operated outside of an atmosphere and should carry enough propellant for the landing, but you would need some kind of attachment to the surface, because of the low gravity.
but as I said it would complicate things

In my humble opinion it would be more efficient to explore those moons with spacecrafts based on mars using local resources as propellant
#22 by wannamoonbase on 30 May, 2006 02:04
Qualifying and doing the work for the LSAM to last long enough for the 6 month cruise would be a significant step.

I agree the moons offer little interest. (If they contained ice inside then maybe, but it would very inaccessible)

The Martian surface has an atmosphere, near 24 hour day, ice deposits, other chemical feedstocks.

Really Mars is a great location to go to, I like the moon because it is close and the communication time would be so easy. But the long term needs to be Mars and it needs to be done with enough Mass of hardware and people that we go and stay and not wait 50 years inbetween visits.

On the Moon side, I think a nuclear powered rover that can be sent into the polar craters and work through the night as well as be driven in near real time would be one heck of a great adventure. The size of a mini van or motor home, lets think big.
#23 by simonbp on 30 May, 2006 14:33
NASA (MSFC, GRC, and LRC) actually did a study on a Mars moon mission to see if it was of any value as a precursor to a landing; the result of the three different mode studies (NEP, NTP, Chemical) was that it would take just as much a landing, if not more if you two landers for each of the moons. (As a side note, due to it's size, the NEP option ending up need more launches than chemical...)

Simon
#24 by rfoshaug on 30 May, 2006 15:05
Wouldn't landing on the Martian moons be more like a docking than a landing? There's not a lot of gravity there.

A Martian moon "docking" would make some sense if you want to go to Mars, but don't want to risk a landing on top of that (a bit like Apollo . A rendezvous with one of the Moons would give NASA some EVA training and useful geological and scientific work while avoiding the risks of landing for a first mission.

On the other hand, after travelling for X months and going all the way to Mars, not landing would significantly reduce the awe-to-risk ratio of the mission.

It'll be very interesting to see what the LSAM will look like. Now that CaLV will use 5 RS68 engines and 10-metre core stage, won't that increase its payload capability (ie. lunar lander max weight)?
#25 by HarryM on 30 May, 2006 17:36
If there is water-ice on Phobos/Deimos it would be a nice resource for a water-cracking plant/refuelling station for your main vehicle. You wouldn't want to haul all of that H2O out of Mars gravity well if you didn't have to. It might also be a good refueling point for missions to the asteroids or outer solar system. Since the gravity is so light, you could probably just settle your main vehicle on the surface w/o any bad weight loads (just have to avoid getting it covered with nasty regolith, maybe some sort of cradle).

EVA's would be dicey, too easy to hop a little too high...
#26 by josh_simonson on 30 May, 2006 20:03
Phobos has a synchronus day/orbit much like the earth's moon, so the mars facing part always faces mars. If one were to build a small outpost there it would be protected from cosmic rays from below by phobos and from above by Mars.

Oxygen can probably be extracted from the regolith of martian moons just as easilly as from our own for ISRU purposes.
#27 by HarryM on 30 May, 2006 20:09
Good point (cosmic ray shielding, no small benefit...). And if you can get H2O (which is likely a component of Phobos due to body density) then so much the better. Easier to crack water than to break down regolith.
#28 by Kayla on 16 Jun, 2006 03:25
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lmike - 21/5/2006 6:33 PM

"CEV must be the number 1 priority, or we don’t have an American human space program." I think there is a weakness even in this proposition. The way it is right now, the CEV/CLV is a dependent pair. Both must have equal priority, or we'll have nothing to launch that CEV on. Or, alternately, we'll have nothing to launch on the CLV. As it is the CEV is tied onto the specific CLV. Architecturally(sp?). A smaller CEV with a 'universal' interstage adapter would fit better into this sequence.

I've got no faith the CLV ever flying! Nor should it.

But, trying to be the ever optimist, CEV still could have a home flying on one or both of the EELV's. I'm a huge fan of a stripped down, affordable crew capsule matched with a MLV rocket making space access affordable. But I'll take the CEV as it is likely to evolve and say close enough.

NASA just needs to learn not to put all of its eggs in one basket. It's time for NASA to learn the concept of assured access to orbit and competition.
#29 by lmike on 16 Jun, 2006 11:58
I understand. My point was that the CEV as planned "needs" the CLV (as planned) in terms of mass, interfaces, diameter and abort profiles. It's a pair made for each other (from the same exploration office). If one doesn't "like" the CLV (as planned), then one doesn't like the CEV (as planned) for important parameters like mass and interfaces. (Sure, the EELVs with enough $$$ could be made to mimic the CLV as substitutes, but why settle for a half solution?! we need to make the whole approach better.) The Big Gemini was a lot lighter than the CEV did the same thing, and could fit on a variety of rockets with thrust (throttle) control.
#30 by Jim on 16 Jun, 2006 12:28
Big Gemini is not lighter. Most of the weight in the CEV is fuel for the TEI. Just as the BG could fly on many LV's so can the CEV, both would have to be optimized for the specific mission. There is nothing special or magically about the BG that gives it any advantage over the CEV. Anyways the BG was a paper study and systems that only exist on paper can do "anything". It just takes a pencil and eraser.
#31 by Jim on 16 Jun, 2006 12:30
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lmike - 16/6/2006 7:45 AM

I understand. My point was that the CEV as planned "needs" the CLV (as planned) in terms of mass, interfaces, diameter and abort profiles. It's a pair made for each other (from the same exploration office). If one doesn't "like" the CLV (as planned), then one doesn't like the CEV (as planned) for important parameters like mass and interfaces. (Sure, the EELVs with enough $$$ could be made to mimic the CLV as substitutes, but why settle for a half solution?! we need to make the whole approach better.) The Big Gemini was a lot lighter than the CEV did the same thing, and could fit on a variety of rockets with thrust (throttle) control.

Big Gemini is not lighter. Most of the weight in the CEV is fuel for the TEI. Just as the BG could fly on many LV's so can the CEV, both would have to be optimized for the specific mission. There is nothing special or magically about the BG that gives it any advantage over the CEV. Anyways the BG was a paper study and systems that only exist on paper can do "anything". It just takes a pencil and eraser.
#32 by lmike on 16 Jun, 2006 12:47
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Jim - 16/6/2006 5:15 AM

Big Gemini is not lighter. Most of the weight in the CEV is fuel for the TEI. Just as the BG could fly on many LV's so can the CEV, both would have to be optimized for the specific mission. There is nothing special or magically about the BG that gives it any advantage over the CEV. Anyways the BG was a paper study and systems that only exist on paper can do "anything". It just takes a pencil and eraser.

The CEV as it stands in its PowerPoint slides and cardboard mock-ups, cannot fly on "many LVs" (without modification, but isn't that the point?) Just the CLV. It's way to heavy (to fit the CLV's launch profile). Btw, it’s also in the pencil and eraser stage. At least the BG had an operational predecessor.
#33 by lmike on 16 Jun, 2006 12:56
I believe you misunderstood. The BG (as planned) was to be a lighter *Earth descent vehicle* Irregardless of the Moon missions. The CEV (as planned) has a heavier *Earth descent vehicle* for little (explained) reason.

I don't have a problem with the CEV's configuraion, just the mass of the CM.
#34 by nacnud on 16 Jun, 2006 13:00
"It's way to heavy."

Only once you fill up the SM with propellant. It might be possible to fly it on LEO/ISS missions with only a partial propellant load which could bring its mass down to what is launchable on the EELVs. A reduced sized SM for LEO/ISS missions might also be possible. However, given the cost and that NASA wants out of the ISS in 2016 I don't think this is a likely outcome.
#35 by Jim on 16 Jun, 2006 13:02
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lmike - 16/6/2006 8:43 AM

I believe you misunderstood. The BG (as planned) was to be a lighter *Earth descent vehicle* Irregardless of the Moon missions. The CEV (as planned) has a heavier *Earth descent vehicle* for little (explained) reason.

I don't have a problem with the CEV's configuraion, just the mass of the CM.

It's because it is designed for lunar return and as a habitation volume since the crew has to live in it. BG was only a ferry.
#36 by Jim on 16 Jun, 2006 13:04
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lmike - 16/6/2006 8:34 AM

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Jim - 16/6/2006 5:15 AM

Big Gemini is not lighter. Most of the weight in the CEV is fuel for the TEI. Just as the BG could fly on many LV's so can the CEV, both would have to be optimized for the specific mission. There is nothing special or magically about the BG that gives it any advantage over the CEV. Anyways the BG was a paper study and systems that only exist on paper can do "anything". It just takes a pencil and eraser.

The CEV as it stands in its PowerPoint slides and cardboard mock-ups, cannot fly on "many LVs" (without modification, but isn't that the point?) Just the CLV. It's way to heavy (to fit the CLV's launch profile). Btw, it’s also in the pencil and eraser stage. At least the BG had an operational predecessor.

So does CEV, it was called the Apollo CSM

GB never got past the proposal stage. CEV went to the development stage and is at least going into design
#37 by Kayla on 16 Jun, 2006 13:28
As I've said, I'm very much in favor of a very scaled down version of the CEV. This should be down through weight savings in the CEV and a dedicated ISS/LEO SM. This could weigh in the 10-12 mT range. Working well with existing EELV MLV's.

But even at the full blown 23 to 25 mT and EELV HLV could actually put the CEV into LEO, saving the CEV's propellant for the mission on the way home from the moon. A 5m diameter (or even 5.5m) will interface well with the 5.4m diameter base module of the Atlas V PLF. This is the portion of the PLF that surrounds the Centaur and would carry the load of a heavy CEV.
#38 by lmike on 16 Jun, 2006 14:19
Ok, fine. I just think that the CEV was tailor made for the pre-selected CLV. That was A Bad Thing. We should have made a CEV that fits on a variety of the existing (with no modifications) CLV's. That would be Good. 'Kay?
#39 by Kayla on 17 Jun, 2006 21:13
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lmike - 16/6/2006 9:06 AM

Ok, fine. I just think that the CEV was tailor made for the pre-selected CLV. That was A Bad Thing. We should have made a CEV that fits on a variety of the existing (with no modifications) CLV's. That would be Good. 'Kay?

A CEV that is intended to fly on numerous LV's is definitely the way to go. NASA currently plans to strictly launch the CEV on the CLV. NASA should intend to launch it on multiple rockets, hence guaranteeing that a LV failure does not ground America's space access again. Haven't we learned anything from the Shuttle's recent history?

My only point is that I am hopeful that a lagging CLV development doesn't and shouldn't doom the CEV.