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#80
by
Dobbins
on 12 Jan, 2006 14:25
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Let's not put the cart before the horse here.
We need a LEO vehicle ASAP. The CEV is going to be flying LEO missions for years before it even goes to the Moon, let alone to Mars. The ISS currently generates O2 by breaking down waste water and it vents H2 overboard as a waste product, so there's a source of free Hydrogen to be had for the ISS missions that will be flown until at least 2015, and likely longer.
The CEV is modular, that means a different SM can be placed behind the CM. It was done with Gemini when the original battery powered SM was replaced with a fuel cell powered SM. It was done with the Soyuz which has had several SM designs over the years. There's no reason it can't be done with a CEV SM if it needs to be changed.
Also right now we are talking about the CEV not a Mars lander. I have never seen much point from the ISRU point of having a SM with a Methane engine. It makes sense for a lander, but hauling Methane up to the orbiting CEV which isn't even the element that would provide the TEI? can't see any point in doing that.
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#81
by
simonbp
on 12 Jan, 2006 14:59
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Dobbins - 12/1/2006 9:25 AM
.... The ISS currently generates O2 by breaking down waste water and it vents H2 overboard as a waste product, so there's a source of free Hydrogen to be had for the ISS missions that will be flown until at least 2015, and likely longer.
...
Would that mean having to run an H2 line all the way from elektron to the US end?
(BTW, LockMart Missiles & Space Huntsville is across the street from UAH, so if I see fireworks at downselect time, I'll post (and then call the fire department!))
Simon
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#82
by
Dobbins
on 12 Jan, 2006 15:25
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simonbp - 12/1/2006 10:59 AM
Would that mean having to run an H2 line all the way from elektron to the US end?
It would have to be looked at to see if it was worth the effort, as compared to finding a means of storing H2 for the duration of a mission. The H2 is there, the question would be "is it worth the effort of using it?" in this or a future design.
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#83
by
rcaron
on 12 Jan, 2006 17:07
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Having the SM use LCH4 provides us the flight experience necessary to truly depend on these engines for the LSAM ascent stage and later Mars flights. If there is no commonality between SM and LSAM ascent then we won't get that experience. According to the report the LSAM descent was also going to be LCH4 based, but there was no substantial advantage to the increased commonality. It made more sense to switch the descent to LH2, which increased payload to surface. They then decided to give the most intensive burn, LOI, to LSAM descent to further optimize surface mass.
I don't think that we'll be using vented H2 as a propellant anytime soon. Its gaseous and in relatively small quantities compared to what is used in the SM. It would require an active pump system and cryogenic cooling to liquifey it before storing it in the SM. It should be noted that while long duration LH2 storage is problematic the SM tanks do a pretty good job at keeping the heat out. Besides, once the CEV is at ISS the only remaining burn is for reentry, and since CEV serves as a lifeboat that capability should always be guaranteed.
So the CEV really has no use for that LH2 unless it was going somewhere else (say the Moon). But, in that case, the ISS' inclination is very poor for deep space missions so it'd take a lot more dV to get the whole thing done vs a 28.5deg inclination. If ISS was in a different orbit I'd agree with you; might as well use it. Things being the way they are I'd say that ISS should have an electric propulsion system sent up and use the GH2 as the primary propellant. Start building that orbit back up to 400km instead of the 350km its been at for so long. Or perhaps actually (ever so slowly) put it into a descent inclination.
No doubt going from battery to fuel cell was a big deal in Gemini, but the Gemini SM didn't have a propulsion capability beyond its RCS. All the big orbital changes were done with a docked Agena. Changing from LCH4 to a hypergolic would be a massive overhaul. New engines, new thrusters, new tanks, new feedline & thruster heating requirements, different corrosive/dedgredation properties. These differences are outlined in ESAS' propellant choice analysis in Ch4 & 5. In short, changing out the propellant types would be a massive overhaul of the SM.
I agree that the CEV will not have the opportunity to use ISRU, even on a Mars flight. The idea is to perfect the technology before hand so we can trust it when we start using it for ISRU. Also LCH4 long term storability is better than LH2. Not hypergolic good of course, but its doable.
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#84
by
Polecat
on 12 Jan, 2006 17:40
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rcaron - 12/1/2006 12:07 PM
Changing from LCH4 to a hypergolic would be a massive overhaul. New engines, new thrusters, new tanks, new feedline & thruster heating requirements, different corrosive/dedgredation properties. These differences are outlined in ESAS' propellant choice analysis in Ch4 & 5. In short, changing out the propellant types would be a massive overhaul of the SM.
Which is one of the reasons that methane was ommited from the ESAS relating to the Moon mission section, it appears. Saving costs and keeping timelines in order appears to be at the top of Griffin's menu right now.
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#85
by
Firestarter
on 12 Jan, 2006 23:36
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Mars is not even worth talking about right now. 2030 is 24 years away.
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#86
by
Bruce H
on 13 Jan, 2006 01:51
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Although the point is we do. We know we're going to the Moon, so the Moon is requirement filled on available cash. If we go to Mars then we can worry about that then.
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#87
by
rcaron
on 13 Jan, 2006 02:38
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As defined by the President, we are undertaking a "human return to the Moon by the year 2020, in preparation for human exploration of Mars and other destinations"
Other relevent quotes: "lunar exploration activities to enable sustained human and robotic exploration of Mars and more distant destinations in the solar system"
"Develop the innovative technologies, knowledge, and infrastructures both to explore and to support decisions about the destinations for human exploration"
"Use lunar exploration activities to further science, and to develop and test new approaches, technologies, and systems, including use of lunar and other space resources, to support sustained human space exploration to Mars and other destinations."
This is all straight from the White House's
A Renewed Spirit of Discovery. Regardless of one's opinions about the outlined objectives, this is NASA's direction. Lunar efforts develop the technologies and the knowhow for Mars flights. This means flight testing advanced life support systems that recycle virtually all water, verifying our habitat structures can shield astronauts from radiation, developing high-mobility EVA suits and rovers and a protocol so every EVA footstep isn't directed by Mission Control. It means developing the launch infrastructure, in-space propulsion, and software capable of Mars flights.
And yes, it means developing ISRU-capable engines.
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#88
by
Bruce H
on 13 Jan, 2006 02:52
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vanilla - 12/1/2006 9:20 PM
Bruce H - 12/1/2006 8:51 PM
Although the point is we do. We know we're going to the Moon, so the Moon is requirement filled on available cash. If we go to Mars then we can worry about that then.
Why are we going to the Moon?
It's a testing ground for the technology and infrastructure we are building. If we can do it all with successful results on the Moon, then we sure can do it on Mars. No reasoning works for me to assume we can do it for Mars without testing on the Moon.
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#89
by
Bruce H
on 13 Jan, 2006 03:17
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For sure.
Now can you find me the cash it would cost to build this new engine and keep within a timeline that works?
If the cash was there we could do what we want, but it's not, so let's do what we can with what we've got, go to the Moon, prove those parts of the ESAS and build the support for Mars funding.
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#90
by
Jamie Young
on 13 Jan, 2006 03:57
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What's your solution then?
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#91
by
Avron
on 13 Jan, 2006 04:06
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vanilla - 12/1/2006 11:29 PM
NASA's problem is not now, nor has ever been, a lack of funding. NASA is awash in funding. NASA's problems are more...fundamental. One of the worst mistakes we could make would be to assume that more funding would make things work better. Quite the contrary.
Care to expand ? what is fundamentally the problem?
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#92
by
Orbiter Obvious
on 13 Jan, 2006 04:15
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This could be good as I've never understood where 17 billion is going and NASA is supposed to be out of cash and needing more. Please tell us what we're missing.
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#93
by
Orbiter Obvious
on 13 Jan, 2006 04:16
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vanilla - 12/1/2006 11:14 PM
NASA's fundamental problem is a lack of relevance to the national constituency. This manifests itself in the form of presidential and Congressional apathy, with exceptions for congressional representatives in districts where NASA is locally relevant.
Health care is nationally relevant, so politicians discuss it and contrast their positions against others. So are education, defense, homeland security, and the environment.
NASA must find a mission for itself that is nationally relevant. The last time it had one was Apollo, and the national relevance was in the form of nationalism and the fear of Communist expansion. With the successful landing on the Moon, this rationale reached resolution and the national relevance abated. NASA has not had national relevance since.
All the funding in the world won't fix this basic problem--rather, additional funding will antagonize those constituencies who do not feel as though the expediture of funds has any relevance to them, which are basically all constituencies outside of the NASA field centers and major contractors.
This is an unpleasant fact to state, especially in a forum such as this, but it would be my fondest wish if we could put our heads together and uncover a mission for NASA that fulfills this basic need. I can state the problem, but the solution eludes me.
You mean like an asteriod?
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#94
by
rcaron
on 13 Jan, 2006 04:27
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The problem is that NASA, while being an agency that can do "aything", is not an agency that can do "everything". NASA's funding priorities are too diverse, its scope too broad. NASA does everything from biomedical research to aerodynamics, supercomputers to deep space probes. NASA maintains the most powerful communication network in the world (DSN), and envisions next-generation air trafic control. NASA pioneers advanced robotics such as Robonaut, and maintains a education program to help teachers inspire their students to persue science & engineering careers. NASA helps NOAA with their weather satellites and provides environmental monitoring in the "mission to planet Earth"
These are the many directions NASA has taken since their single primary vision (Apollo) was canceled. These are all great things, I truly love every single one of these programs.
And therein lies the problem. Some of the problems have to be cut or sacraficed to make room for a single primary direction again. And everytime one of these programs are cut people, rightly so, scream bloody murder.
Would additional funding help? Of course it would, but to get more than what is available is unlikely. Despite NASA's budget being more than the rest of the world's space funding, NASA triees to do so much more than the rest. NASA as a whole has the same problem that the Shuttle had during its design - its everything to everybody, and now excels at nothing.
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#95
by
Doug Stanley
on 13 Jan, 2006 04:29
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Yes, I am THAT Doug Stanley...I just stumbled across this forum and you all seem very well informed and reasonable. Many of you have read our ESAS Report. What do you think of it and the architecture (good and bad)?
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#96
by
Space101
on 13 Jan, 2006 04:33
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Welcome to the site (and its forum here).
The ESAS Study is a work of art. I think everyone loved it.
This site is a bit of a STS support stronghold and if you wanted a sign of the excitement and hope which this study gave, then look no further than the reactions on the ESAS threads. Edit: Thanks Gyro for supplying the links.
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#97
by
Doug Stanley
on 13 Jan, 2006 04:35
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Thanks
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#98
by
gyro2020
on 13 Jan, 2006 04:38
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#99
by
Avron
on 13 Jan, 2006 04:38
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vanilla - 13/1/2006 12:33 AM
rcaron - 12/1/2006 11:27 PM
NASA as a whole has the same problem that the Shuttle had during its design - its everything to everybody, and now excels at nothing.
While I agree with the general flavor of your argument, I must hasten to point out that there are quite a number of activities where NASA excels far and beyond any other group could even hope. I don't see anybody else putting rovers on Mars for two years that climb mountains and drive through craters. I don't see other countries smashing probes into comets and figuring out all the theories are wrong. I'm not sure who's planning to send another mission to Pluto.
NASA kicks butt in a lot of areas, and I'm super proud of that. But we are missing the central mission--the reason around which all other activities can be aligned. Before you tell me that is the "vision", ask yourself, honestly, if that mission is nationally relevant. If you believe it is, I won't attempt to alter your opinion.
I ask myself, looking for an angle, it can be focused on money( power) or fear, fear works very well, however, I also look at JPL and MER, and look how well they have done. I don't think its NASA, its manned space flight IMHO
