Author Topic: To the Moon and Beyond–Examining the EELV-L1 Approach v2  (Read 61285 times)

Offline Marsman

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #140 on: 12/31/2007 12:18 am »
Perhaps you could use a nuclear stage to go from Earth orbit to Lunar orbit, and a dedicated chemical (or nuclear) lander. I could see a three launch architecture with existing EELVs-
 
1. Small Orion on Atlas 401
2. LSAM Descent on DIV-H or Atlas H or 551
3. LSAM Ascent (possibly with descent hydrogen) on DIV-H or Atlas H or 551

40-50 mt EELV's could do a two launch architecture

A big question that I have is why are people so afraid of nuclear in space? There is no danger of pieces falling back from a transfer back to Earth as previously explained, and the engine wouldn't even have enough material to go critical in the first place. The only danger that I can see is a nuclear upper stage ignited on a suborbital trajectory - if it doesn’t ignite, then it is coming back. But if it is ignited in orbit, there is no danger.

Offline clongton

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #141 on: 12/31/2007 12:25 am »
Quote
meiza - 30/12/2007  7:56 PM

I'm not a nuclear engineer, but if there is so little material (or it's in a sparse matrix) that it can't even melt itself when made to a pile, (I assume it reaches a steady state where it radiates as much heat as it generates, glowing white hot) what will the hydrogen temperature actually be when it flows through the core. I mean, these seem as pretty opposite design parameters. You want a hot core to make hot hydrogen for high ISP and high thrust but you want a cool core for failure safety. The power is the same in both cases, for an engine that can not explode.

Someone could easily calculate the loss of coolant accident temperature for various size cores with various power ratings with the Beer-Lambert law....
There is a medium point at which the steady state reaction is self sustaining, producing enough heat to provide useful thrust, yet cannot produce any more heat based on the amount of fissile material that is (not) available. The NERVA engineers identified and built to that point.

Quote
As far as I know, the nerva designs were not safe in this regard (and not in many other regards either). But I could be wrong.
In the beginning, the early NERVA designs would shake themselves apart and break. That stopped the reaction and the engine was destroyed in the process; physically, not explosively. There was never an explosion. There was one "rapid disassembly" event, but that was not accidental. It was deliberately induced to help the engineers identify several break points. The engineers were basically learning as they went. But by the time they were getting ready to flight test the engine, they had had several "very long" runs with the engines with no problems of any kind. The selected materials could withstand extreme temperatures, enough to allow the nuclear reactions to occur and be sustained for considerable lengths of time before the engineers simply shut down the engine because it was well, "just running". They had found that point where they could sustain the engine at maximum power, at the extreme temperature that all the fuel would provide, without damaging the engine. That's the engine they were planning to fly post-Apollo 17. The picture I posted is, I believe, that engine. Everything in engineering is a balance. Design the "widget" to get the maximum performance from the least input and design it so that it can't exceed its safety limits. Ultimately, that's what the NERVA engineers did. They did good. I would like to see us pick up where they left off and move the development forward, to even more powerful, and safer, engines. After all, we have years of materials development under our belts now, that they did not have the benefit of. We can use that knowledge to make the engines safer first, then increase the power afterward as engine development continues.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline clongton

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #142 on: 12/31/2007 12:31 am »
Quote
Marsman - 30/12/2007  8:18 PM

Perhaps you could use a nuclear stage to go from Earth orbit to Lunar orbit, and a dedicated chemical (or nuclear) lander. I could see a three launch architecture with existing EELVs-
 
1. Small Orion on Atlas 401
2. LSAM Descent on DIV-H or Atlas H or 551
3. LSAM Ascent (possibly with descent hydrogen) on DIV-H or Atlas H or 551

40-50 mt EELV's could do a two launch architecture

A big question that I have is why are people so afraid of nuclear in space? There is no danger of pieces falling back from a transfer back to Earth as previously explained, and the engine wouldn't even have enough material to go critical in the first place. The only danger that I can see is a nuclear upper stage ignited on a suborbital trajectory - if it doesn’t ignite, then it is coming back. But if it is ignited in orbit, there is no danger.
"Ignition" of a nuclear engine is a lot simpler than a chemical engine. In the simplest terms, it's just venting gas across a hot pile to heat the gas and letting it exhaust out the nozzle. Obviously the devil is in the details, but with nuclear engines, there are a LOT fewer details.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline meiza

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #143 on: 12/31/2007 01:01 am »
Let's calculate a bit.
If we want a nuclear J-2 equivalent, that's 100 tons or 1000 kN of thrust and and ISP of perhaps 1000 s meaning v_ex 10 km/s.
That means a kinetic power of 5 GW for the exhaust jet.  I think the biggest state of the art stationary nuclear reactors are that size in thermal power.
The hydrogen flow rate would be 100 kg/s. Heated from cryogenic to about 2600-2700 K or 2300-2400 degrees C. The core glows white hot.

Now, what happens when this hydrogen flow is for some reason discontinued? Where does all the power go? Stay tuned for the next episode, aired in 2008... ;)

Online mike robel

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #144 on: 12/31/2007 01:08 am »
Crap, when I edit, it sticks the whole post into a single paragraph.  How can I fix that?

Offline clongton

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #145 on: 12/31/2007 01:15 am »
Buzz Aldrin has an interesting proposal out there for 3 constantly cycling "Mars Cyclers". Essentially, they are 3 identical spacecraft that continually cycle between the orbits of Mars and the Earth. If you want to go to Mars, you fly up to meet the incoming cycler and ride it to Mars, getting off the cycler to enter Mars orbit while the cycler continues on its way. Coming home is exactly the opposite. Catch the next cycler and ride it home.

I wonder - is something similar possible with the moon? Could we have 2 or 3 spacecraft constantly "cycling" back and forth to/from the moon that we could just "catch a ride on" to take us to/from the moon?
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline clongton

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #146 on: 12/31/2007 01:25 am »
Quote
meiza - 30/12/2007  9:01 PM

Let's calculate a bit.
If we want a nuclear J-2 equivalent, that's 100 tons or 1000 kN of thrust and and ISP of perhaps 1000 s meaning v_ex 10 km/s.
That means a kinetic power of 5 GW for the exhaust jet.  I think the biggest state of the art stationary nuclear reactors are that size in thermal power.
The hydrogen flow rate would be 100 kg/s. Heated from cryogenic to about 2600-2700 K or 2300-2400 degrees C. The core glows white hot.

Now, what happens when this hydrogen flow is for some reason discontinued? Where does all the power go? Stay tuned for the next episode, aired in 2008... ;)
Meiza;
This entire subject is near and dear to me and I could easily let myself get off topic here and take this thread way out from where it should be. Let's you and me, and Ross as well, put a hold on the details of this particular discussion regarding nuclear powered spacecraft for now and perhaps pick it up later in a different thread. We could perhaps also get vanilla and a few others to join in I think. I'd like that. I appreciate your comments and thoughts, both here and on the thorium energy forum, so I think we could really get deep in to this, and I would like that very much. But we're getting OT again on this thread.

I would suggest, that for purposes of "this" thread, that we just agree for the time being that a nuclear tug or spacecraft of "some" sort is possible but there are things to be worked out before that becomes practical, and then let it go at that, at least here in this thread. What do you think?
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline clongton

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #147 on: 12/31/2007 01:28 am »
Quote
mike robel - 30/12/2007  9:08 PM

Crap, when I edit, it sticks the whole post into a single paragraph.  How can I fix that?
Try hitting a return 2x at each point where you want the sentence to break. Alternatively, cut and paste the quote you want to reply to into Word, do your word engineering there (including spell check), and then paste it back into the reply window. That's "usually" what I do, because I really need the spell checker :)
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Online mike robel

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #148 on: 12/31/2007 01:42 am »
reformated and posted again from above.

I think you guys are thinking too far in advance and such things would turn off both the public and the congress. I would go a little slower.


First get back to the moon. If necessary, with a three launch campaign. Launch 1 CEV, Launch 2 LSAM, Launch 3 EDS. With this we would need another EELV Pad, the CEV could launch on an Atlas 502, the LSAM on a Delta IV Heavy, and the EDS on whatever booster we choose to use. All that would be required is for the 3 payloads to rendezvous and dock. Maybe Launch 1 would be the EDS. One orbit later, the CEV would launch and dock, and 2 orbits later, the LSAM would launch and the EDS/CEV stack would dock with it. No extended loiter. Maybe, except for the EDS, do it with hypergolics. LSAM ascent stage is retained for MM and return to earth. CEV may only need a small SM to dock with the EDS and perhaps to serve as a part of a lifeboat function.


Could the EDS carry enough fuel for TLI, LOI, and ELI if it a Centaur class stage? Could we chain 2 together to get the same effect?


What about longer Earth to Moon cycle times of 7 days vice 3, which would require less energy/propellent.


We have previously demonstrated the ability to launch multiple spacecraft and dock them within 2 orbits.


Phase II. Propellent depot with a lunar taxi. The CEV and LSAM launch as before, but the EDS cycles between Earth and the moon. Nuke development begins.


Phase III. Direct deliver of payloads to the lunar surface to extend surface time. Perhaps small habitats. This would be the time to introdce a larger launch vehicle, if possible, to enable larger payloads. Nuke stage testing.


 Phase IV. Nuke operational, takes the place of the cycling EDS. Larger payloads to lunar surface. Start Mars Mission module development.


Each phase should take no more than 8 -10 years, preferably a little less, so as to be accomplished within the terms of a single president, 4 house elections and 2 senatorial election cycles. Political attention usually does not last that long and public attention could be even less.  This approach also gives us a fully operational capability in each cycle, in case political support is lost for future expandability.  It might also offer a safe way for partner nations to join in the effort.

Finally, it avoids the Viking syndrome, which I discussed earlier in the thread.


Each phase should have different "flag and footprint" missions/objectives to keep public interest up:

1.  Return to the Moon.

2.   Polar Landing

3. Far Side Landing/establish communication satellite network around the moon.

3a. Establishment of automated optical/radar observatory on far side of moon.

4. Long duration stays - 2 - 6 weeks. At the same time, send mars probes to accurately determine radiation exposure for a two years mars expedition, so we can develop counters to it, if required. Mars sample returns.

5. Semi-permanent base camps, stays up to 6 months, resupplied by direct deliver of payloads to lunar surface. Expansion of the fuel depot to a manned space operations center

6. Introduce the nuke, long duration orbital missions (up to 6 months ) cycling between earth and moon as test for 6 month voyage to mars. Crew than does 1 year surface stay on Moon. Long duration - 6 month orbital mission before return to earth, rehearsing everything except the actual Martian voyage. Orbits would likely go out 500 - 750,000 miles. Maybe include rendezvous with an NEO, if we know where any are.


The point of the phases is, as I stated, (1) to tie them to electoral cycles to maximize political support, (2) they provide building blocks that are incremental and do not accomplish too much at once, (3) are designed to keep public support through more complicated missions, and (4 ) provide building block to Mars missions, which can conveniently be tied to taking place 20 or 30 years into the future.


I would think the public would go nuts over the spectacle of 3 or 4 launches within 8 hours. Pad construction, increased booster construction, need for perhaps 4 firing rooms would also help economics.


Such an approach could be compared to the opening of the West with first scouts going (Lewis and Clark), the first homesteaders, the development of routes and wagon trains to the west (cycling stages) and the establishment of army garrisons (semi-permanent base camps) , the coming of the railroad (nukes), and then the digging of the Panama Canal or Magellan’s circumnavigation of the world (voyage to Mars ).At the same time, it would be useful to tie it into Manifest Destiny except tie it to the whole planet, West to Mars: Manifest Destiny and planetary migration in the 21st Century.


Offline kkattula2

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #149 on: 12/31/2007 03:21 am »

I think everyone (NASA included) is still missing the point of "Return to the Moon" as part of VSE. It's supposed to be practice and a learning experience for "Mars Exploration". There's just no point in developing a Moon architecture that won't apply to Mars.

Key point: A Mars mission is going to require a big, extended duration, habitat module. Including things like personal space, emergency radiation shelter, water & air recycling and probably some sort of centifugal, artificial gravity. This is NOT going to land on Mars. Ideally, it should return to Earth orbit or L1/L2 for servicing, resupply & reuse.

The Moon architecture should incorporate this module so as to test it over shorter durations, and much closer to home. i.e. If something breaks, like air or water recycling, it's only a few days to home, not six months or more.

Similarly, TLI and TMI injection are of approximate size. A Mars Ascender has similar delta v to a Moon Lander/Ascender.

Design your Mars architecture, and test as much as possible by going to the moon.

 


Offline kkattula2

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #150 on: 12/31/2007 04:27 am »
One way of side stepping the political (public paranoia) problems of Nuclear Thermal Rockets, may be Solar Thermal Rockets.
Basically using mirrors to concentrate sunlight on a heat exchanger, then pass propellant (probably LH2) through it.  

These should give Isp close to NTR, around 900 for simple, indirect LH2 heat exchange. However, thrust to weight ratio would be much lower than NTR, so no good for landers. But for a TMI or TLI type, in-space application, who cares if acceleration lasts 5 minutes or 50? In fact lower thrust means lower loads on structures, especially docking ports.

Assuming LH2 boil off can be managed, a mass ratio of less than 4 would get you from LEO to LM(ars)O and back.

Offline libs0n

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #151 on: 12/31/2007 05:17 am »
Quote
kkattula2 - 30/12/2007  11:21 PM

I think everyone (NASA included) is still missing the point of "Return to the Moon" as part of VSE. It's supposed to be practice and a learning experience for "Mars Exploration". There's just no point in developing a Moon architecture that won't apply to Mars.

Key point: A Mars mission is going to require a big, extended duration, habitat module. Including things like personal space, emergency radiation shelter, water & air recycling and probably some sort of centifugal, artificial gravity. This is NOT going to land on Mars. Ideally, it should return to Earth orbit or L1/L2 for servicing, resupply & reuse.

The Moon architecture should incorporate this module so as to test it over shorter durations, and much closer to home. i.e. If something breaks, like air or water recycling, it's only a few days to home, not six months or more.

Similarly, TLI and TMI injection are of approximate size. A Mars Ascender has similar delta v to a Moon Lander/Ascender.

Design your Mars architecture, and test as much as possible by going to the moon.


I have a different point of view.  I believe that a moon mission should be designed solely around getting to the moon.  A Mars mission is not going to happen for another 20 years, and the lunar profile can be significantly different than a Mars profile that to confine the execution of one with the constraints of the other does not make a lot of sense to me.  When it comes time for a Mars mission, then wipe the slate clean and use some of the ideas and tools we'll have had 20 years to come up with.  I would have never described myself as a lunatic, but the moon is an interesting destination in its own right that is deserving of the same kind of consideration martians seem to insist should be reserved for Mars.

What you're describing, save for the artificial gravity and the rad shelter, is a space station.  There was a book I read a few months ago called Leaving Earth that detailed the Soviet space program and the later Mir/ISS efforts, and it's clear that that is what the Russian program was testing out incrementally with their space station modules.  Some figures in the book had the same thought concept, with one even going so far as to attempt a long duration mission of the same timeframe a transit to Mars would take.  I would also really like to see a program involving what you have in mind; perhaps Bigelow's stuff will take up along these lines, or maybe after the ISS NASA might get their act together.

Incidentally, I've been turning over Moon mission architecture elements in my head for the past few weeks, and one of my ideas featured something similar, a refuelable EDS with a habitat module that would take on a crew in Earth orbit, drop them off to a Lunar Lander come the Moon, and do the reverse on the way back.  In my mind it would have been a true spaceship cycling between the Earth and the Moon, but I did not have the required expertise to figure out if it was feasible, and was most likely barking up a smaller tree than I had thought.

Offline tankmodeler

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #152 on: 12/31/2007 03:33 pm »
Quote
kkattula2 - 30/12/2007  11:21 PM

Ideally, it should return to Earth orbit or L1/L2 for servicing, resupply & reuse.
I suspect that isn't going to happen until there is enough traffic to Mars to make it economical to retain the MM. Remember, to retain a Mars MM you have to brake it into Earth orbit, which means you have to take the fuel for that all the way to Mars and back, which puts you on the up-spiral in weight for the entire system. If you're going to Mars to support a colony (in some far-off and to-be-desired future) then retaining the MM is probably the way to go. Along with high efficiency nuke propulsion, fuel depots at either end and a buncha other "colony level" stuff I hope we have at some point. But that won't be in my lifetime or in yours. :)

At the "boots & footprints" stage, cheap is the way to go and providing for the fuel to brake the hab module isn't at all cheap. Making more hab modules, at the rate of one every 2-4 years (based on what the mission rate will be) would make a lot more sense. Once you have put the money into the design & building of one, then building more for the low mission rate wouldn't be enomously more expensive.

Paul
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Offline clongton

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #153 on: 12/31/2007 03:39 pm »
Quote
tankmodeler - 31/12/2007  11:33 AM

I suspect that isn't going to happen until there is enough traffic to Mars to make it economical to retain the MM. Remember, to retain a Mars MM you have to brake it into Earth orbit, which means you have to take the fuel for that all the way to Mars and back, which puts you on the up-spiral in weight for the entire system. Paul
If the spacecraft is NEP or SEP powered and the start/return point is EML2, then the returning spacecraft would be thrusting almost all the way home. By the time they arrive in the vicinity of EML2, they could probably be captured there with simple thruster maneuvers. -Reusable interplanetary spacecraft!
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Offline tankmodeler

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #154 on: 01/01/2008 06:48 pm »
Quote
clongton - 31/12/2007  11:39 AM

Quote
tankmodeler - 31/12/2007  11:33 AM

I suspect that isn't going to happen until there is enough traffic to Mars to make it economical to retain the MM. Remember, to retain a Mars MM you have to brake it into Earth orbit, which means you have to take the fuel for that all the way to Mars and back, which puts you on the up-spiral in weight for the entire system. Paul
If the spacecraft is NEP or SEP powered and the start/return point is EML2, then the returning spacecraft would be thrusting almost all the way home. By the time they arrive in the vicinity of EML2, they could probably be captured there with simple thruster maneuvers. -Reusable interplanetary spacecraft!
Yes, that's true, but you're still carrying the fuel all the way there & back. A reuseable vehicle will also be heavier due to the longer service life expectations. Being heavier always carries a committment to fund the infrastructure to support that additional weight. Nuke engines may reduce the point where reusability becomes economically viable, but I suspect that until there is some sort of colony or at least a frequently repeating mission rate (and, as much as I'd like to see it, I don't think that it's going to be that way from the beginning) there just won't be the committment to building into the program the ability to expand that way right from the beginning.

NASA has _never_ built for the long term or for possible additional capability. They have always built just to the limits of the requirements mainly for cost reasons. I don't see that changing and I don't see the guaranteed mission rates being supported to drive to re-useable anything (whether for moon, mars or even LEO CEVs).

Commercial exploitation will provide the impetus to do things over and over bringing with it the requirements of reusability to reduce overall sustainability costs. NASA just doesn't work in that envelope.

Paul
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Offline kfsorensen

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #155 on: 01/01/2008 07:18 pm »
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tankmodeler - 1/1/2008  1:48 PM

Yes, that's true, but you're still carrying the fuel all the way there & back.

The fuel load isn't nearly as bad as with a chemical rocket.

Offline tankmodeler

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #156 on: 01/02/2008 12:06 am »
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vanilla - 1/1/2008  3:18 PM

Quote
tankmodeler - 1/1/2008  1:48 PM

Yes, that's true, but you're still carrying the fuel all the way there & back.

The fuel load isn't nearly as bad as with a chemical rocket.
True, but that is what I mean about it changing the point where it become viable. It still doesn't do anything for the first missions where NASA would have to choose to build-in more weight. And they _never_ do that. They would have to have been given a requirement to make the system re-useable and that's not going to come without a higher level directive (like congress or at least the Administrator).

Paul
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Offline kkattula2

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #157 on: 01/02/2008 07:11 am »
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libs0n - 31/12/2007  5:17 PM

I have a different point of view.  I believe that a moon mission should be designed solely around getting to the moon.  ...

I agree that the moon is worth going to for its own sake, and for long term occupation you would want an optimized transportation system.  But that's not the clearly stated objective in the VSE. Mars is the goal. The Moon is just practice. Until & unless that changes, ESAS is not implementing the VSE.  Whether it should change is another question.

I would like to see NASA gradually develop more and more capability. It needn't be all in one go:

1)  Develop a crew launcher to LEO
2)  Put a long duration habitat (HM) in LEO (no propulsion, but designed to handle interplanetery injection stresses), test with crew
3)  Put a propellant depot (PD) in LEO, and start filling it
4)  Put a propulsion module (PM) in LEO (similar to an EDS), practice filling at depot
5)  Test PM on loop around the Moon, Lunar Orbit insertion, LEO return
6)  Use PM to send PD 's to Mars Orbit, Lunar orbit, L1 etc,
7)  Use PM to send crewed HM on various Lunar, NEAR & Mars tests
8)  Put Moon or Mars specific landers in LEO, dock with HM, test
9)  Use PM to send HM and lander to Moon, Mars etc

Almost all of this could be done with EELV's, with minimal "assembly", but quite a few dockings.
Heavier lift would make it a bit simpler though.

Things like docking and propellant transfer will have to become routine one day. Now is the time they should be developed.

"...we choose (to do these things) not because they are easy, but because they are hard." anyone?


Offline A_M_Swallow

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #158 on: 01/02/2008 08:28 am »
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clongton - 29/12/2007  3:15 PM
{snip}
Ross outlined an EELV Heavy Lift a little ways above that was better than the Ares. It beats the Ares hands down - more powerful, less costly and fielded much sooner. And most important - sustainable. On top of that, the Orion would fit on the unenhansed core of that launcher and get the US back into manned space within 2 years of Shuttle retirement. What's not to love? LM and Boeing are perfectly capable of proposing this launch vehicle and then they could do what I suggested above; sell the customer the “equivalent” of the “Mack” truck. But apparently, the EELV company CEO’s do not want to play. They don’t have the balls to compete. Oh well. Then let them stew in it. That is a sad commentary from my perspective. I would “LOVE” to see that competition against STS. I am for STS because it's the only heavy lift option offered. If LM & Boeing would get off their scardy-cat lazy butts and compete - well it could be a totally different ball game and I'm not so sure STS would win a fair competition like that. But apparently they are too cheap to spend the cash to put the proposal in place. They have been feeding at the government cow's teet for too long. It's time to wean them and make them earn their business, just like everyone else. They could produce such an awesome launch vehicle family for this nation if only their leaders would grow a little hair. I know that the designers and engineers that work for them are just itching to do this because they know beyond a doubt that they can. Those employees have more faith in themselves, their abilities and their companies than their leaders do and that is just plain sick. It turns my stomach. So I guess as far as EELV is concerned, it's 25mT pop-guns or nothing.

The man-rated extra heavy EELV design specification does not have to come from LH or Boeing.  It could come from a 'retired' employee.

Offline meiza

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Re: To the Moon and Beyond–Examining the EELV-L1 Approach v2
« Reply #159 on: 01/02/2008 11:41 am »
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kkattula2 - 2/1/2008  8:11 AM

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libs0n - 31/12/2007  5:17 PM

I have a different point of view.  I believe that a moon mission should be designed solely around getting to the moon.  ...

I agree that the moon is worth going to for its own sake, and for long term occupation you would want an optimized transportation system.  But that's not the clearly stated objective in the VSE. Mars is the goal. The Moon is just practice. Until & unless that changes, ESAS is not implementing the VSE.  Whether it should change is another question.

I would like to see NASA gradually develop more and more capability. It needn't be all in one go:

1)  Develop a crew launcher to LEO
2)  Put a long duration habitat (HM) in LEO (no propulsion, but designed to handle interplanetery injection stresses), test with crew
3)  Put a propellant depot (PD) in LEO, and start filling it
4)  Put a propulsion module (PM) in LEO (similar to an EDS), practice filling at depot
5)  Test PM on loop around the Moon, Lunar Orbit insertion, LEO return
6)  Use PM to send PD 's to Mars Orbit, Lunar orbit, L1 etc,
7)  Use PM to send crewed HM on various Lunar, NEAR & Mars tests
8)  Put Moon or Mars specific landers in LEO, dock with HM, test
9)  Use PM to send HM and lander to Moon, Mars etc

Almost all of this could be done with EELV's, with minimal "assembly", but quite a few dockings.
Heavier lift would make it a bit simpler though.

Things like docking and propellant transfer will have to become routine one day. Now is the time they should be developed.

"...we choose (to do these things) not because they are easy, but because they are hard." anyone?


Yeah there are some good ideas in this post. Doing incremental development, testing, no need for new launchers for every phase...

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minimal "assembly", but quite a few dockings.
- that's a pretty good way to boil down what can be achieved with 25 t launchers. Berthing or even just attaching some propellant lines with a robotic arm too, which could be much easier for a supply craft than docking.

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