Author Topic: 1.5 Lunar Launch variation  (Read 19418 times)

Offline marsavian

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1.5 Lunar Launch variation
« on: 09/18/2010 01:28 pm »
So it looks like a SD-HLV is being built first. Is it technically feasible to launch the Astronauts in a Lunar Lander connected to the EDS on the SLS and use the Lander as the LAS and lifeboat ? Orion could go up unmanned on a Delta IV Heavy first and the SLS could be sent up later to dock with it. Without humans forcing a low-g launch profile and a LAS the D-IV Heavy will be able to lift a heavier Orion not to mention easy growth options like J-2X and GEMs taking a 45mT Orion into the realms of possibility. The hypergolic AJ-10 would not suffer the same boiloff problems as the cryogenic EDS meaning any delays would not be a major problem if Orion was kept waiting in orbit. I suppose it all boils down to how well a modified Lunar Lander could behave as a safe LAS. Opinions ?
« Last Edit: 09/18/2010 01:30 pm by marsavian »

Offline Warren Platts

Re: 1.5 Lunar Launch variation
« Reply #1 on: 09/18/2010 01:42 pm »
Quote from: marsavian
1. So it looks like a SD-HLV is being built first.

2. taking a 45mT Orion into the realms of possibility.

3. The hypergolic AJ-10 would not suffer the boiloff problems

1. Keep dreamin'.

2. You've got to be kidding....

3. Hypergolic lunar landers are a step in the wrong direction. Half the reason for going to the Moon is to get lunar derived propellant--that means LH2/LO2. Boiloff is a non-issue. Read the ULA papers.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline marsavian

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Re: 1.5 Lunar Launch variation
« Reply #2 on: 09/18/2010 01:46 pm »
Boiloff is an issue when you want to dock two LVs in LEO. I was referring solely to the AJ-10 on Orion as the Lunar lander could have any engine that did the job.
« Last Edit: 09/18/2010 02:31 pm by marsavian »

Offline pathfinder_01

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Re: 1.5 Lunar Launch variation
« Reply #3 on: 09/18/2010 02:55 pm »
There is more than one way to skin a cat. Going up in a lander is probably a bad idea. The Orion capsule is built for entry descent and landing on earth and those systems could be used for abort scenarios. The lander is built for landing on some other body and forcing it to be water proof(in case of abort into ocean) or even capable of landing on earth could make for a less than optimal lander design.

One option would be to use commercial crew to launch the crew into leo to join their craft.  Using a space station could be helpful for this purpose. Orion plus lander is launched by SLS months ahead of time automatically docks to the station.  Commercial launches the crew and docks to the station while SLS readies the EDS. The EDS launches and the crew leave the commercial craft to come home on auto pilot.  If the commercial craft could perform a crew rotation on the station there are savings.

Another option is to launch the lander first, then launch Orion and EDS together. Orion docks with lander in LEO.  The lander could be supported in LEO via a reusable unmanned satelight or a space station that provides power and other things the lander needs for  support.

A final option is to use a propellant depot to hold the cryogenic propellants until needed. Boil off could be much more manageable in the depot since for an EDS more insulation equals less performance. Or you could use a hypergolic one to hold propellant for the lander. Both options free mass on the launching booster.
 
Finally the only mission where it would make any sense for Orion to grow would be a lunar one where it performs the exact same role as Apollo (i.e. No refueling or staging at L1/L2). Or if you want to stretch Orion’s tanks for a direct trip to L1/L2 (In which case you don’t need an EDS).  And in both cases the only thing that would be added would be propellant.

 In general you don’t want the capsule itself to gain mass. More mass equals longer peek heating on reentry and more work the EDL systems in general.  What you could do is add a some Soyuz like upper module that could contain extra supplies.

IMHO a 1.5 launch tries to shoe horn too much into too little. Either launch it all at once ala Apollo or break it into manageable pieces (i.e. ISS). If you use 1.5 you have forced your smaller launcher to be much larger than is commercially viable(i.e. a LEO craft does not need  enough propellant for  1500+ delta V)and you may have a boil off problem.

Both add cost. You might as well use the larger launcher twice or do the mission in three.

Finally if you must the delta IV heavy can lift 30-50MT to LEO with some non J2 upgrades.
« Last Edit: 09/18/2010 02:59 pm by pathfinder_01 »

Offline marsavian

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Re: 1.5 Lunar Launch variation
« Reply #4 on: 09/18/2010 03:31 pm »
Don't we want a lander that can eventually float on Titan ? ;)

Offline JohnFornaro

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Re: 1.5 Lunar Launch variation
« Reply #5 on: 09/18/2010 03:36 pm »
I know what One launch looks like.  What exactly, does a half a launch look like?
Sometimes I just flat out don't get it.

Offline marsavian

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Re: 1.5 Lunar Launch variation
« Reply #6 on: 09/18/2010 03:43 pm »
SLS and EELV Heavy like Ares 1 and 5 doing one Lunar mission. ESAS terminology.

Offline douglas100

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Re: 1.5 Lunar Launch variation
« Reply #7 on: 09/18/2010 03:52 pm »
From Marsavian

Quote
Is it technically feasible to launch the Astronauts in a Lunar Lander connected to the EDS on the SLS and use the Lander as the LAS and lifeboat ?

I suppose it's technically feasible. But I have to say it sounds like a crazy idea to me. Are you seriously proposing launching the crew in a vehicle with no heat shield and no escape system? No one would ever consider doing such a thing.
Douglas Clark

Offline Warren Platts

Re: 1.5 Lunar Launch variation
« Reply #8 on: 09/18/2010 03:57 pm »
Quote
No one would ever consider doing such a thing.

That depends on the person....
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline douglas100

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Re: 1.5 Lunar Launch variation
« Reply #9 on: 09/18/2010 03:58 pm »
Sorry, I misread your post. You mentioned an escape system. But to launch a crew in a vehicle without a heat shield is crazy. What would happen to the crew if the the upper stage engine shut down just before reaching orbital velocity?
Douglas Clark

Offline marsavian

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Re: 1.5 Lunar Launch variation
« Reply #10 on: 09/18/2010 04:00 pm »
It's a powered descent vehicle. If it is well above the atmosphere it can dock with the waiting Orion and the crew can come back on that if they need to.
« Last Edit: 09/18/2010 04:02 pm by marsavian »

Offline pathfinder_01

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Re: 1.5 Lunar Launch variation
« Reply #11 on: 09/18/2010 04:06 pm »
It's a powered descent vehicle. If it is well above the atmosphere it can dock with the waiting Orion and the crew can come back on that if they need to.

Yes but if they are riding in it they wont be above the atomsphere for sometime. LAS are for challenger type disaters.

Offline marsavian

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Re: 1.5 Lunar Launch variation
« Reply #12 on: 09/18/2010 04:08 pm »
If the descent module engine fails you could have parachutes on the ascent module and come down on that.

Offline pathfinder_01

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Re: 1.5 Lunar Launch variation
« Reply #13 on: 09/18/2010 04:15 pm »
If the descent module engine fails you could have parachutes on the ascent module and come down on that.

So now you have parachutes on both the capsule and the lander? Plus a heat shield is needed once the rocket gets supersonic. 

Just launch the crewed capsule with the EDS or use commercial crew or assemble in orbit. The 1.5 isn't the best nor the only way to do it. In fact even with Apollo, the Saturn IB could not launch a fully fueled Apollo CM. In order to do LEO they had to short load it. In the case of Orion, it is pre short loaded because it only has enough propellant to return from the moon not break into and return.

Go with a TWO SLS launch or go with three launches.  There is no .5 launch in the real world.  A .5 launch is like buying a large size detergent item and a small size detergent of the same product.  If the large size is too small either buy an extra large or buy two large.  A .5 forces you to squeeze a lunar sized payload item onto a LEO sized rocket. IF you must do so then it would be best to launch the lander unmanned and the crew plus EDS.
« Last Edit: 09/18/2010 04:26 pm by pathfinder_01 »

Offline marsavian

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Re: 1.5 Lunar Launch variation
« Reply #14 on: 09/18/2010 04:17 pm »
Mars has an atmosphere so they will not be wasted on a Lander.

Offline pathfinder_01

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Re: 1.5 Lunar Launch variation
« Reply #15 on: 09/18/2010 04:27 pm »
Mars has an atmosphere so they will not be wasted on a Lander.

Ok lets step back a bit, why are you tring to make Orion larger?

Offline marsavian

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Re: 1.5 Lunar Launch variation
« Reply #16 on: 09/18/2010 04:36 pm »
So it can perform LOI, have greater shielding and/or carry some of the lunar payload. An unmanned version seems a good fit for the Delta IV Heavy which will be cheaper than a SLS especially if it looks like Ares V. Just doing some unconventional out of the box thinking to see if there is any mileage in the idea.
« Last Edit: 09/18/2010 04:46 pm by marsavian »

Offline pathfinder_01

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Re: 1.5 Lunar Launch variation
« Reply #17 on: 09/18/2010 05:47 pm »
So it can perform LOI, have greater shielding and/or carry some of the lunar payload. An unmanned version seems a good fit for the Delta IV Heavy which will be cheaper than a SLS especially if it looks like Ares V. Just doing some unconventional out of the box thinking to see if there is any mileage in the idea.


Orion currently maxes out Delta IV heavy.  Would need more than 1 launch or upgrade Detla to do it.
« Last Edit: 09/18/2010 05:48 pm by pathfinder_01 »

Offline Sparky

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Re: 1.5 Lunar Launch variation
« Reply #18 on: 09/18/2010 06:28 pm »
Don't we want a lander that can eventually float on Titan ? ;)
Mars has an atmosphere so they will not be wasted on a Lander.

Commonality is great, but you still don't want to have a heat shield or parachutes on a lunar lander. Every kilogram spent on them is a kilogram that can't be used carrying instruments, supplies, equipment, astronauts, etc.

Besides, if your plan involves giving a lander emergency reentry capability, why even bother with the Orion at all?

Offline marsavian

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Re: 1.5 Lunar Launch variation
« Reply #19 on: 09/18/2010 06:37 pm »
You need the Orion CM for reentry from the Moon. Parachutes and rentry shielding could be disposed for Lunar landers once successful docking has taken place with Orion in LEO.
« Last Edit: 09/18/2010 06:40 pm by marsavian »

Offline Jorge

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Re: 1.5 Lunar Launch variation
« Reply #20 on: 09/18/2010 06:48 pm »
It's a powered descent vehicle. If it is well above the atmosphere it can dock with the waiting Orion and the crew can come back on that if they need to.

Dude, give it up. Nothing like this is going to fly. Abort capability *throughout ascent* is a firm requirement. You are not going to get away without putting a full heat shield and recovery system on the lander if you expect to launch it with people, and that is an incredible waste of mass. Sell the idea to a crazy billionaire doing a private mission if you want, but NASA will never, ever go for this.
JRF

Offline pathfinder_01

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Re: 1.5 Lunar Launch variation
« Reply #21 on: 09/18/2010 06:57 pm »
Oddly if he didn't use SLS, it could be made to work with a phase II EELV. One core sized powerful enough to lift a 40 ton Orion to LEO and the combined sized powerful enough to lift 70 tons or so to LEO.

Offline Downix

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Re: 1.5 Lunar Launch variation
« Reply #22 on: 09/20/2010 02:04 am »
I may note, the AJAX proposal alternative SD-HLV, enables a far more contiguous 1.5 architecture than this proposal.  This one has redundant support structure and costs associated with it.  AJAX, however, enables the use of the already man-rated Atlas V for a crewed Orion, with the AJAX SD-HLV, with coherent components and launch structures shared between the two.

AJAX, BTW, is an all-liquid SD-HLV whereby the SRB's are replaced with Atlas CCB's, giving a far more powerful and flexible architecture, while simultaneously sharing support structure between the SD-HLV and the ISS crew launcher, as the Atlas V is already slated to be used for not one, but two ISS crew support vehicles, the Dream Chaser and CST-100.  Therefore, utilizing it for Orion as well would streamline support, as well as improve economics to operate.
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Offline marsavian

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Re: 1.5 Lunar Launch variation
« Reply #23 on: 09/20/2010 05:03 am »
This one has redundant support structure and costs associated with it. 

If your lander is planning to enter Mars it will need heat shielding anyway to resist that atmosphere although granted it's a lot thinner. If you also make the ascent module heat resistant with parachutes you also have greater crew safety if that module fails to launch off Mars successfully as the crew could then abort to the surface and await rescue. The real trick would be in tying up the two different requirements of aborting from Earth ascent and descending /ascending into Mars in one piece of hardware without major mass growth. The other obvious benefit of this architecture is that you don't have to lift a specific LAS on the CEV launcher leaving more usable mass for the CEV.
« Last Edit: 09/20/2010 05:10 am by marsavian »

Offline pathfinder_01

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Re: 1.5 Lunar Launch variation
« Reply #24 on: 09/20/2010 05:09 am »
This one has redundant support structure and costs associated with it. 

If your lander is planning to enter Mars it will need heat shielding anyway to resist that atmosphere although granted it's a lot thinner. If you also make the ascent module heat resistant with parachutes you also have greater crew safety if that module fails to launch off Mars successfully as the crew can abort to the surface and await rescue. The real trick would be in tying up the two different requirements of aborting from Earth ascent and descending /ascending into Mars in one piece of hardware without major mass growth. The other obvious benefit of this architecture is that you don't have to lift a specific LAS on the Orion launcher leaving more usable mass for Orion.

For mars lifting Orion is the least of your worries. Orion on a mars trip at best would be a craft used to send crew to the stack and return after. Most of the mass will not be Orion or the lander plus no way you are going to get a mars trip in 1.5 launches. 

Offline Sparky

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Re: 1.5 Lunar Launch variation
« Reply #25 on: 09/20/2010 06:19 am »
This one has redundant support structure and costs associated with it. 

If your lander is planning to enter Mars it will need heat shielding anyway to resist that atmosphere although granted it's a lot thinner. If you also make the ascent module heat resistant with parachutes you also have greater crew safety if that module fails to launch off Mars successfully as the crew can abort to the surface and await rescue. The real trick would be in tying up the two different requirements of aborting from Earth ascent and descending /ascending into Mars in one piece of hardware without major mass growth. The other obvious benefit of this architecture is that you don't have to lift a specific LAS on the Orion launcher leaving more usable mass for Orion.

If we're going to Mars, we will take a Lander designed for Mars. If we're going to the moon, we will take a lander designed for the moon. There is little advantage in having one design intended for both, and the result would be a vehicle sub-optimal for both worlds.

Not to mention the fact that all of this added stuff adds huge penalties to your launch. Even if you jettison the shields and chutes in LEO as you said earlier, (which would make the whole thing heavier with the release mechanisms and all) you're carrying up so much dead weight that you might as well just put the Orion on top of the stack and call it Apollo.

Offline Downix

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Re: 1.5 Lunar Launch variation
« Reply #26 on: 09/20/2010 05:41 pm »
This one has redundant support structure and costs associated with it. 

If your lander is planning to enter Mars it will need heat shielding anyway to resist that atmosphere although granted it's a lot thinner. If you also make the ascent module heat resistant with parachutes you also have greater crew safety if that module fails to launch off Mars successfully as the crew can abort to the surface and await rescue. The real trick would be in tying up the two different requirements of aborting from Earth ascent and descending /ascending into Mars in one piece of hardware without major mass growth. The other obvious benefit of this architecture is that you don't have to lift a specific LAS on the Orion launcher leaving more usable mass for Orion.

For mars lifting Orion is the least of your worries. Orion on a mars trip at best would be a craft used to send crew to the stack and return after. Most of the mass will not be Orion or the lander plus no way you are going to get a mars trip in 1.5 launches. 
Precisely. 

Orion is a crew launch and recovery vehicle, period, the end, deal with it.  For any meaningful BEO operations a specialized vehicle, a space-only or a lander, is what will be necessary.  This may be in the 1.5 Architecture.  After all, Orion *can* reach the moon on top of Atlas V if paired with an ACES derived SM (getting back is another story) so it could meet up with a lander in LLO.  If refueling from the lander is an option, and no reason why it shouldn't be, then the 1.5 LLO approach may be the right one.  Or not.  We don't know until we simulate the hell out of things, do we?
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Offline luke strawwalker

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Re: 1.5 Lunar Launch variation
« Reply #27 on: 09/21/2010 07:36 pm »
Oddly if he didn't use SLS, it could be made to work with a phase II EELV. One core sized powerful enough to lift a 40 ton Orion to LEO and the combined sized powerful enough to lift 70 tons or so to LEO.

That's something I suggested a couple years ago or so when discussing 'clean sheet' options when A I/V were just starting to go wrong...

Develop EELV upgrade capable of launching Orion in a single stick configuration and use the three-body heavy version of it for the HLV...

I was shot down in flames... didn't gain traction then don't expect it will now either, though as more time passes it looks more and more like the only sane and potentially affordable way to do it...

Probably have to see another TOTAL clusterfudge again before it'll be considered...

Later!  OL JR :)
NO plan IS the plan...

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Offline luke strawwalker

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Re: 1.5 Lunar Launch variation
« Reply #28 on: 09/21/2010 07:46 pm »
This one has redundant support structure and costs associated with it. 

If your lander is planning to enter Mars it will need heat shielding anyway to resist that atmosphere although granted it's a lot thinner. If you also make the ascent module heat resistant with parachutes you also have greater crew safety if that module fails to launch off Mars successfully as the crew could then abort to the surface and await rescue. The real trick would be in tying up the two different requirements of aborting from Earth ascent and descending /ascending into Mars in one piece of hardware without major mass growth. The other obvious benefit of this architecture is that you don't have to lift a specific LAS on the CEV launcher leaving more usable mass for the CEV.

I'm not going to pretend to be an expert on Mars EDL designs for manned landers, but this much I DO know...

Ain't no way, NO WAY, that a manned Mars lander is going to have TWO heatshields and parachute sets on both the descent and ascent stages.  NEVER gonna happen!  The extra mass would absolutely KILL any design EVER being capable of working-- too much wasted mass in the ascent stage, which means heavier/larger heatshield/parachutes/propulsive descent tanks/engines for the descent/lander stage, and too much extra unnecessary weight riding on the ascent stage in the form of the 'nominally' unneeded ascent stage heat shield/EDL equipment, driving it's propellant masses and therefore engine needs too high, which of course drives up the requirements for the descent/landing stage.   

And, playing devil's advocate a moment, IF a failure on ascent led to a second reentry and landing, what exactly would the crew "be rescued" by?? 

This is total fantasyland stuff... Mars is gonna be risky and difficult as it is... whatever we build for manned landings is going to be on the hairy edge of being capable of delivering the necessary masses anyway, and the risks WILL be high.  If we can't accept the risks and insist on hamstringing the effort with rediculous redundancies like this, it'll NEVER happen, and really we have no business even wasting time trying.  SMART decisions will make it possible, not useless hand-wringing exercises to justify useless capabilities...

All IMHO... OL JR :)
NO plan IS the plan...

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Offline pathfinder_01

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Re: 1.5 Lunar Launch variation
« Reply #29 on: 09/21/2010 11:34 pm »
Oddly if he didn't use SLS, it could be made to work with a phase II EELV. One core sized powerful enough to lift a 40 ton Orion to LEO and the combined sized powerful enough to lift 70 tons or so to LEO.

That's something I suggested a couple years ago or so when discussing 'clean sheet' options when A I/V were just starting to go wrong...

Develop EELV upgrade capable of launching Orion in a single stick configuration and use the three-body heavy version of it for the HLV...

I was shot down in flames... didn't gain traction then don't expect it will now either, though as more time passes it looks more and more like the only sane and potentially affordable way to do it...

Probably have to see another TOTAL clusterfudge again before it'll be considered...

Later!  OL JR :)

Luke you committed such blasphemy as to suggest putting Orion on an EELV gasp! What other blasphemy will you commit next!  It is politics that are damaging NASA.  The companies\people involved in STS don’t want to be locked out of the replacement.

Apollo and Ares both had the same problem. Apollo decided that time was of the essence and developing a totally new rocket to send Apollo to LEO was not a good idea. They took the Saturn I and developed it to the Saturn IB and got on to the hard work (the lunar stuff).

Ares figured that NO launcher was available to send people to the ISS and therefore spent time and money that should have gone to Ares V and lunar systems. The end result was that the planned gap was widened and commercial is looking like a better bet.

Anyway why did griffin choose a .5 launch anyway?  It just adds problems.  A capsule sized for lunar work is going to mass much more than a capsule sized to be an ISS taxi.  A 15MT launcher could be more than enough for an ISS taxi, but way too weak for lunar one. It forces you to develop two totally new rockets from scratch. Even Apollo didn’t do that.

Were politics so entrenched that he couldn’t develop an LEO Orion (with small service module) launch able on Atlas then develop BOE Orion with larger service module launched on NASA rocket?

Offline A_M_Swallow

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Re: 1.5 Lunar Launch variation
« Reply #30 on: 09/22/2010 12:27 am »
{snip}
And, playing devil's advocate a moment, IF a failure on ascent led to a second reentry and landing, what exactly would the crew "be rescued" by?? 

Initially no one can rescue them. Later the astronauts can return to the Mars Base in the Mars rover.

Online 93143

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Re: 1.5 Lunar Launch variation
« Reply #31 on: 09/22/2010 03:44 am »
If we're going to Mars, we will take a Lander designed for Mars. If we're going to the moon, we will take a lander designed for the moon. There is little advantage in having one design intended for both, and the result would be a vehicle sub-optimal for both worlds.

The delta-V required for a Mars lander/ascender that refuels on the surface is very similar to that required for a lunar lander/ascender that doesn't.

It has been remarked (by ULA, I think) that a single-stage lunar access vehicle can be easier and cheaper to design and build than a two-stage one, since the delta-V requirement isn't all that high - the mass fraction requirement is about 3 for hydrogen or 4 for methane, if your depot is at L1 or L2.

If we are going to maintain the capability to land on the moon while we go for Mars (I certainly hope no one here is arguing that we shouldn't), it would sure be a lot cheaper to maintain production infrastructure for one type of lander rather than two.  You'd probably want more thrust for Mars, so either have engine mounts left empty for the moon (like DIRECT's boattail) or design the lander so it can take either RL-10s or RL-60s...

Offline A_M_Swallow

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Re: 1.5 Lunar Launch variation
« Reply #32 on: 09/22/2010 09:46 am »
{snip}

If we are going to maintain the capability to land on the moon while we go for Mars (I certainly hope no one here is arguing that we shouldn't), it would sure be a lot cheaper to maintain production infrastructure for one type of lander rather than two.  You'd probably want more thrust for Mars, so either have engine mounts left empty for the moon (like DIRECT's boattail) or design the lander so it can take either RL-10s or RL-60s...

Rocket men are too mass fixated, so heat shields on lunar landers will not survive.  What may survive is common cabins - the Mars lander reuses the lunar landers controls, avionics, life support system and airlock.

Offline Warren Platts

Re: 1.5 Lunar Launch variation
« Reply #33 on: 09/22/2010 02:47 pm »
Quote from: marsavian
If your lander is planning to enter Mars it will need heat shielding anyway to resist that atmosphere although granted it's a lot thinner. If you also make the ascent module heat resistant with parachutes ...

Quote from: Sparky
If we're going to Mars, we will take a Lander designed for Mars. If we're going to the moon, we will take a lander designed for the moon. There is little advantage in having one design intended for both

The ULA paper says their DTAL lunar lander could be modified for Mars as a straightforward increase in volume and thrust. E.g., I ran the numbers for an ACES-71-based lander (with an ascender with somewhat enlarged tanks) would have enough delta v to do a fully propulsive landing without need of TPS's or parachutes, and still have enough propellant leftover for the ascender to get back to low orbit. Thus both landers could come from the same assembly line.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Online 93143

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Re: 1.5 Lunar Launch variation
« Reply #34 on: 09/23/2010 03:00 am »
Rocket men are too mass fixated, so heat shields on lunar landers will not survive.  What may survive is common cabins - the Mars lander reuses the lunar landers controls, avionics, life support system and airlock.

Who said anything about a heat shield?  This is fully propulsive landing on Mars with plenty of margin.  Just start from a higher orbit, so you aren't going very fast by the time you hit the atmosphere.

If you really need a heat shield, bolt-on should be fine.

...okay, granted I haven't done the math on this.  And Mars' atmosphere appears to be bigger than Earth's, even if it's not as dense near the ground...
« Last Edit: 09/23/2010 03:31 am by 93143 »

Offline A_M_Swallow

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Re: 1.5 Lunar Launch variation
« Reply #35 on: 09/23/2010 03:30 am »

Who said anything about a heat shield? {snip}

Lots of people.  You quoted reply #25 which is part of a debate about heat shields.

Online 93143

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Re: 1.5 Lunar Launch variation
« Reply #36 on: 09/23/2010 03:33 am »
Okay, fine.  But I didn't say anything about heat shields.

I actually had forgotten what the conversation had been about...

Anyway, I've got a Mars standard atmosphere calculator running; I may or may not attempt a landing profile one of these days...

Offline A_M_Swallow

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Re: 1.5 Lunar Launch variation
« Reply #37 on: 09/23/2010 03:51 am »
Okay, fine.  But I didn't say anything about heat shields.

No worries.

It was not obvious that you had found the fourth option - neither lander has a heat shield.

Offline Proponent

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Re: 1.5 Lunar Launch variation
« Reply #38 on: 09/23/2010 05:39 am »
Who said anything about a heat shield?  This is fully propulsive landing on Mars with plenty of margin.

Descending through the Martian atmosphere at speeds low enough that a heat shield is unnecessary will entail enormous gravity losses.

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Re: 1.5 Lunar Launch variation
« Reply #39 on: 09/23/2010 07:09 am »
Look, you can take off on the same prop load, right?  How is that not just the reverse? - except that going down, drag works in your favour, and the high-gravity-loss regime is now near the end of the burn when the lander is lighter, rather than near the beginning when it's full.  Besides, to do a round trip between EML2 and the lunar surface takes more delta-V than a Mars launch, so you have nearly a km/s of margin.

You don't need a heat shield for launch, do you?

As I said, I haven't actually done the math on this yet...

Online 93143

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Re: 1.5 Lunar Launch variation
« Reply #40 on: 10/06/2010 08:48 am »
Anybody know what the Martian atmosphere is like at high altitudes?  The model I'm using is probably fine for airplanes, but I'm still getting significant dynamic pressure well into the range where I've floored the temperature at a randomly guessed value to prevent it from becoming zero...

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Offline douglas100

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Re: 1.5 Lunar Launch variation
« Reply #42 on: 10/06/2010 02:35 pm »
I thought this thread was supposed to be about a lunar launch architecture.
Douglas Clark

Offline marsavian

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Re: 1.5 Lunar Launch variation
« Reply #43 on: 10/06/2010 03:17 pm »
Yes but any commonality with the eventual Mars lander is to be preferred.

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Re: 1.5 Lunar Launch variation
« Reply #44 on: 10/06/2010 06:15 pm »
http://www.grc.nasa.gov/WWW/K-12/airplane/atmosmre.html ?

Yeah, that's the one I'm using.  The temperature goes to zero a little past 110 km altitude, which is no good as I'm starting from a 500 km orbit...

EDIT:  Never mind; I found something.  Not a model, but decent for visual fitting.  Eyeballing, it looks like ~125 K floor and a 7.5*h thermospheric rise intercepting the floor at about 147-148 km or so.

Oddly, the lower atmosphere in the picture doesn't behave the same as it does in that model...  oh well; it's not like I'll be descending at Mach 4 in the middle of the discrepancy...  wait, yes it is...
« Last Edit: 10/07/2010 09:19 am by 93143 »

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Re: 1.5 Lunar Launch variation
« Reply #45 on: 10/10/2010 12:41 am »
Okay, I think I've got something.

The initial orbit is equatorial, altitude 500 km.  Engine delta-V for the descent is 4.28 km/s.  With two minutes of hover included, the total is 4.72 km/s.  Drag only accounts for 28 m/s.

The run was done with RL-60s running LOX/LH2, leading to a mass ratio of 2.85.  With LOX/CH4, I estimate that the same delta-V would require a mass ratio of 3.63.  Those numbers may be optimistic as they require a large expansion ratio, which may not be feasible.

Either way, the descent requires significantly less delta-V than a round trip between EML1 and one of the lunar poles (over 5.5 km/s) or even an equatorial site (still over 5 km/s).

It is possible that some of that surplus performance could be applied to reducing the peak temperature via further trajectory shaping, or perhaps including a few extra pieces to shield small, sharp parts...  Or maybe it's good as it stands, and the extra performance can land it in the polar regions if an electric mothership or tug can put it in a polar orbit...

Radiative equilibrium temperatures were calculated assuming an emissivity of 0.6.  Stagnation-point heating loads were calculated using Chapman's equation, which is probably invalid with the engines thrusting forward, but hey...
« Last Edit: 10/10/2010 07:42 am by 93143 »

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Re: 1.5 Lunar Launch variation
« Reply #46 on: 10/11/2010 05:19 am »
Actually, I calculate that if the lander were designed with enough delta-V for the lunar poles with Lagrange-point staging, it would have enough spare performance in a near-equatorial Mars landing to bring a tank of hydrogen for ISRU, sufficient to fill its own fuel tank with methane for the trip back up.

This might result in a small landed payload for high latitudes, or even not work at all, but at high latitudes there should be ice, so you'd have the option of either using in situ hydrogen to produce methane or just using the LOX/LH2 version of the lander...

I wonder (and wonder why I'm wondering) whether it would be cheaper/easier to supply a Mars base in an ice-poor area by using a mass driver at the lunar north pole, or by just trucking ice overland...
« Last Edit: 10/12/2010 06:07 pm by 93143 »

Offline alexw

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Re: 1.5 Lunar Launch variation
« Reply #47 on: 10/11/2010 06:19 am »
I wonder (and wonder why I'm wondering) whether it would be cheaper/easier to supply a Mars base in an ice-poor area by using a mass driver at the lunar north pole, or by just trucking ice overland...
  That's how Kim Stanley Robinson did it ;)
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Offline luke strawwalker

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Re: 1.5 Lunar Launch variation
« Reply #48 on: 10/22/2010 04:43 pm »
Luke you committed such blasphemy as to suggest putting Orion on an EELV gasp! What other blasphemy will you commit next!  It is politics that are damaging NASA.  The companies\people involved in STS don’t want to be locked out of the replacement.

Apollo and Ares both had the same problem. Apollo decided that time was of the essence and developing a totally new rocket to send Apollo to LEO was not a good idea. They took the Saturn I and developed it to the Saturn IB and got on to the hard work (the lunar stuff).

Ares figured that NO launcher was available to send people to the ISS and therefore spent time and money that should have gone to Ares V and lunar systems. The end result was that the planned gap was widened and commercial is looking like a better bet.

Anyway why did griffin choose a .5 launch anyway?  It just adds problems.  A capsule sized for lunar work is going to mass much more than a capsule sized to be an ISS taxi.  A 15MT launcher could be more than enough for an ISS taxi, but way too weak for lunar one. It forces you to develop two totally new rockets from scratch. Even Apollo didn’t do that.

Were politics so entrenched that he couldn’t develop an LEO Orion (with small service module) launch able on Atlas then develop BOE Orion with larger service module launched on NASA rocket?


"Shuttle (sorry, need to stop here for a second and just say that I have to use stupid words to get my point across. I know that means I must have a weak argument, but that's why I use bad words)." is alive and well??  (grins)  It's politics... and politics make strange bedfellows... 

Your correct.  That's why "spiral development" went out the window, and "SDLV" supporters (Griffin & Co.) were put in to replace them. 

IF (and that is a BIG, BIG IF) SDLV were done RIGHT (and so far I have seen NO reason to believe that it will be-- quite the contrary, as the cherry picking done on ESAS to justify the plain silly Ares I and V, etc.) it COULD be a viable path forward, CERTAINLY the MOST viable path to heavy lift. 

BUT, of course that requires a high enough flight rate to JUSTIFY heavy lift.  Any HLV that is only going to fly a mission every other year is going to be impossibly expensive to support, especially if it has to carry the costs of massive infrastructure to support SRB's and such.  What would shuttle flights cost if they only flew every other year??  Even at twice a year it'd be "too high" but that cost might be deemed acceptable to keep US spaceflight capabilities rolling until a replacement could be fielded. 

EELV-derived or clean sheet kerolox would doubtlessly be better TECHNICAL solutions, and could be designed with an eye to minimizing costs/overhead, but, as you said, it locks the "shuttle (sorry, need to stop here for a second and just say that I have to use stupid words to get my point across. I know that means I must have a weak argument, but that's why I use bad words)." out, so it's NEVER going to be politically viable-- not unless and until the whole thing crashes and burns and simply collapses irretrievably...

SO, maybe, just *maybe* we're seeing a genuine 'reboot' here with SLS and maybe, just *maybe* we'll see something TRULY SDLV come out of this that can leverage what we already have (and have paid for) to come up with something we can use. 

Course, I have LITTLE faith that will happen-- far MORE likely that NASA will again retread the same old "Battlestar Galactica" plans in a "new" version of their super-duper uber-booster that will be completely unaffordable and unsustainable and suck all the air out of the room, leaving NO money for payloads and missions, which will leave the rocket with NO reason to exist in the first place... (meet the new boss, same as the old boss...)  "There's nothing new under the sun." 

Of course, at that point, it may have become SUCH an unsavory mess that there will be little interest in funding ANYTHING to replace it...

I guess time will tell... I hope I'm wrong, but a LOT of folks hoped they were wrong about Ares too and we see now how THAT turned out...

Later!  OL JR :)
NO plan IS the plan...

"His plan had no goals, no timeline, and no budgetary guidelines. Just maybe's, pretty speeches, and smokescreens."

Offline luke strawwalker

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Re: 1.5 Lunar Launch variation
« Reply #49 on: 10/22/2010 04:49 pm »
Quote from: marsavian
If your lander is planning to enter Mars it will need heat shielding anyway to resist that atmosphere although granted it's a lot thinner. If you also make the ascent module heat resistant with parachutes ...

Quote from: Sparky
If we're going to Mars, we will take a Lander designed for Mars. If we're going to the moon, we will take a lander designed for the moon. There is little advantage in having one design intended for both

The ULA paper says their DTAL lunar lander could be modified for Mars as a straightforward increase in volume and thrust. E.g., I ran the numbers for an ACES-71-based lander (with an ascender with somewhat enlarged tanks) would have enough delta v to do a fully propulsive landing without need of TPS's or parachutes, and still have enough propellant leftover for the ascender to get back to low orbit. Thus both landers could come from the same assembly line.

That would be the way to do it, if the math works out...

If we can't start 'standardizing' things so they can be retasked for more than a single purpose, there is NO WAY a Mars mission will EVER be affordable... let alone sustainable. 

Moon either for that matter...

Why has DTAL been glossed over??  Why is NASA not pursuing something similar, even if they have NIH syndrome that precludes any possibility of them accepting ULA's proposal?? 

The LM was an acceptable idea-- it got the job done and it was pretty straightforward, but that doesn't mean it's the best solution for a 'scaled up' mission like Cx has planned all along.  The state of the art and technology has moved forward a LOT in the intervening years, and just as designs for a LOT of things have moved on and advanced, DTAL seems like a more advanced way of doing things, from what I've seen and read...

Later!  OL JR :)
NO plan IS the plan...

"His plan had no goals, no timeline, and no budgetary guidelines. Just maybe's, pretty speeches, and smokescreens."

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