Author Topic: ALTERNATIVE - NON SLS: Exploration Gateway Platform - Reusable Lunar Lander  (Read 57864 times)

Offline Bill White

  • Senior Member
  • *****
  • Posts: 2019
  • Chicago area
  • Liked: 5
  • Likes Given: 0
A depot in LEO has no reason to exist without a depot further out.

Build an EML Gateway and competitively bid the logistical support for that Gateway and if LEO depots make sense, they will emerge from the free market.
EML architectures should be seen as ratchet opportunities

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 27033
  • Minnesota
  • Liked: 6927
  • Likes Given: 4886
Assuming a 2200 m/s dv, 320 Isp, and 4 mt dry mass, the hypergolic crasher stage needs to be about 23 mt wet. Remember it's taking a 15 mt lander from L1 to near the lunar surface, not doing an Apollo style descent from LLO.

No way does your SEP tug mass less than 4 mt.

DS1 with only 2.5 KW (2.1 for the thrusters), massed nearly 500 kg. You're looking at more like 10+ mt dry for the SEP, and therefore 9 mt of Xenon per transfer. 10 with tankage and transfer equipment.

Even using your numbers it's still around 8 mt of Xenon.

23 + 8= 31 mt. Far too much to launch on one D-IVH. 

I did do the math before posting. :)


DS1 is a poor example. It uses the far poorer-performing NSTAR. NEXT is far better and has been raised to around TRL6 or so already. I don't know if another spacecraft will use NSTAR again. There are already commercial thrusters better than NSTAR. Even NEXT is not the limit of performance, either.

BTW, I used 30km/s exhaust velocity. But let's look at the higher, >4190s Isp NEXT thruster (has undergone years of testing).

As far as 23 mT for a crasher stage... True for a hypergolic stage, but since we're using Boeing's numbers, we could also use their methane/LOx engines, which they claim can do around >370s for pump-fed, which works out to around 19.5mT. That leaves around 5.5mT for Xenon plus Xenon tank, or around 5mT of Xenon proper.

Using NEXT's peak Isp of 4190s means that the 19.5mT of payload (and the tug, of course) can be sent through the 7km/s with about 4.5mT of Xenon. It may take a little longer, but that's still doable on a Delta IV Heavy. :) Not only that, but you could still put enough Xenon on that Delta IV Heavy to get the tug back to LEO.

Methane/LOx is space-storable (and according to Boeing, can do >370s Isp pump-fed... pump-fed also means better tank mass), NEXT can do 4190s Isp, so as long as you're willing to wait a little longer, a Delta IV Heavy can still put a large enough crasher stage and Xenon propellant up in a single launch to fit in Boeing's architecture. ;)

(And 4190s Isp is not the limit... operate at a higher voltage or use the cheaper and lighter Argon instead of Xenon, and you can get even higher Isp relatively simply.... over 12000s Isp for ion thrusters like NSTAR and NEXT has been demonstrated in the lab... the higher the voltage and thus Isp, the higher the electrical efficiency for ion thrusters)
« Last Edit: 12/05/2011 04:50 PM by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline mmeijeri

  • Senior Member
  • *****
  • Posts: 7442
  • Martijn Meijering
  • NL
  • Liked: 70
  • Likes Given: 162
I see a lot of arm-waving on this thread but little or no numbers.

Not all arguments need numbers, but I have plenty of numbers if you're interested.

Quote
There's no way to get a crewed Orion to EML-1 with only one launch of any LV smaller than SLS.

EELV Phase 1 would be smaller than both SLS and FH. And a crew taxi to L1/L2 could be smaller than Orion - there's no need for Orion, though there is a need for a service module.

Quote
There's no way to get a (non-ZBO) hydrolox crasher stage to EML-1 with only one launch of any LV smaller than SLS.

LOX/LH2 crashers should wait for commercial depots.

Quote

There's no way to get a hypergolic crasher stage to EML-1 with only one launch of any LV smaller than SLS or Falcon Heavy.

There's no need to do it in one launch, since it could be launched dry and only fueled at L1/L2.

Quote
Change to a hypergolic crasher and you will need 6 x D-IVH, with at least 2 of them launched in a 2 week period.

Not with a LOX/methane ascent stage.

Quote
Change to all hypergolic beyond LEO and you will need 8 x D-IVH, but you can launch the as far apart as need be. But the maximum mission rate will be less than 1.5 per year. ULA can't make enough cores to exceed that.

If there's enough demand, production capacity will grow. And in addition to Delta there's still Atlas, Falcon 9 and soon Taurus 2. And Proton, Zenit, Ariane... Or, if it is cheaper to develop cryogenic depots, the market will invest in that instead.

Quote
Overall, if you're not going to use SLS, I think somthing like the ULA ACES based architecture would be much better.

More advanced, but in the near term a less ambitious stepping stone would be better. Think in spirals.
« Last Edit: 12/05/2011 04:26 PM by mmeijeri »
We will be vic-toooooo-ri-ous!!!

Offline muomega0

  • Full Member
  • ****
  • Posts: 857
  • Liked: 64
  • Likes Given: 1
A depot in LEO has no reason to exist without a depot further out.

Build an EML Gateway and competitively bid the logistical support for that Gateway and if LEO depots make sense, they will emerge from the free market.

The {launch vehicle} "free market" wants:  more launches and more transfer stages and hence no LEO depot to maximize profits.  Dear taxpayer:  do you want to spend less than 1B by adding some power and pumps to the tanks of a stretched upper stage, or spend multiple billions more sending propellant to a Gateway orbit over 20 years? 

Again, a EML Gateway depot only does not solve the major cost issues with boiloff and disposing of expensive hardware, so the statement:  "has no reason to exist"  has not be substantiated in anyway, nor is it in fact correct.

So who is the "free market"?  Maybe Elon Musk says it more bluntly:
http://www.airspacemag.com/space-exploration/Visionary-Launchers-Employees.html

“If you were sitting at an executive meeting at Boeing and Lockheed and you came up with some brilliant idea to reduce the cost of Atlas or Delta, you’d be fired,” he says. “Because you’ve got to go report to your shareholders why you made less money. So their incentive is to maximize the cost of a vehicle, right up to the threshold of cancellation.”

Offline jongoff

  • Recovering Rocket Plumber/Space Entrepreneur
  • Senior Member
  • *****
  • Posts: 6048
  • Lafayette/Broomfield, CO
  • Liked: 2038
  • Likes Given: 692
A depot in LEO has no reason to exist without a depot further out.

That's not really true.  While I definitely favor a two-depot (LEO and EML1 or EML2) solution, a LEO depot by itself is actually pretty useful.  And for some particular destinations (NEOs with high departure declinations), a LEO depot might be preferable.  There may be some orbital dynamics tricks for getting a EML1/2 departure to high declination, low-C3 targets like NEOs without big penalties, but I still haven't figured those out.  We did figure out though how to do those targets directly from LEO depots with fairly negligible penalties...

Plus, while the markets aren't there yet, once a LEO depot exists there are some potential ways they could play into GEO comsat launch, which would give you a potential non-NASA customer base.  The challenge is that nobody is going to do a business that requires LEO depots to exist before LEO depots are a lot closer to existing.

~Jon

Offline mmeijeri

  • Senior Member
  • *****
  • Posts: 7442
  • Martijn Meijering
  • NL
  • Liked: 70
  • Likes Given: 162
And for some particular destinations (NEOs with high departure declinations), a LEO depot might be preferable.

Why would a departure from LEO be preferable over one from L1/L2 for such destinations?
We will be vic-toooooo-ri-ous!!!

Offline MATTBLAK

  • Elite Veteran & 'J.A.F.A'
  • Senior Member
  • *****
  • Posts: 3829
  • 'Space Cadets' Let us; UNITE!! (crickets chirping)
  • New Zealand
  • Liked: 749
  • Likes Given: 1425
Can anyone tell me what the optimum altitude and inclination would be for a LEO Depot? I'm wondering about thermal 'pollution' from the Earth and the day/night cycles.

EDIT: I know the answer is probably in one of the 'oodles' of long Depot articles I have, but I don't have time to comb through them right now ;)
« Last Edit: 12/05/2011 06:03 PM by MATTBLAK »
"Those who can't, Blog".   'Space Cadets' of the World - Let us UNITE!! (crickets chirping)

Offline pathfinder_01

  • Full Member
  • ****
  • Posts: 1874
  • Liked: 47
  • Likes Given: 0
Can anyone tell me what the optimum altitude and inclination would be for a LEO Depot? I'm wondering about thermal 'pollution' from the Earth and the day/night cycles.

EDIT: I know the answer is probably in one of the 'oodles' of long Depot articles I have, but I don't have time to comb through them right now ;)

It is also one of thoose things where a lot of factors come into play.

Lox/Methane for instance is a lot easier to keep cool in space than lox\loh and hydrazine would be in danger of freezeing in space.

It also depends on what is it's function.

Online douglas100

  • Senior Member
  • *****
  • Posts: 2152
  • Liked: 214
  • Likes Given: 95
Douglas Clark

Offline Rocket Science

  • Senior Member
  • *****
  • Posts: 7986
  • NASA Educator Astronaut Candidate Applicant 2002
  • Liked: 2177
  • Likes Given: 5142
Chuck, the engineering problem with lunar night isn't visibility, it's power and thermal.

In lunar night, you have zero option for solar power, but you have much greater power requirements due to having to heat the crew and electronics (and any hypergolics). Not a happy combination. So unless you mount an RTG on your reusable lander, it's not going to land at night.

Of course, the point is moot, as ostensibly the entire reason for landing is field geology, which will require illumination for rock-hunting (if not power/thermal for the suits).

I envision the lander being a horizontal lander, like the image above or something similar, with deployable solar panels that are stowed for the transit down and back, deployed at the LZ. Initially all landings will be limited to the lunar daytime at the LZ. Eventually, when that no longer remains practical, then power will be supplied by either fuel cells or RTG's, bearing in mind that it will need to provide thermal energy as well as electrical power.

Chuck

Thinking about the Reusable Horizontal Lander a bit more I figured why not marry the ULS’s ACES with the MPCV or even the lighter CST-100. If you land the Rover first and have it remotely drive over to dock with the hatch of the (MPCV or CST-100) after it lands, you now have a “mud room” and extra Hab space and access to the suits all without having to go EVA on the surface until you wish to. Most of this hardware exists in some form and studies done.
 
Regards
Robert
« Last Edit: 12/05/2011 11:43 PM by Rocket Science »
"The laws of physics are unforgiving"
~Rob, Physics instructor, aviator, vintage auto racer

Offline Rocket Science

  • Senior Member
  • *****
  • Posts: 7986
  • NASA Educator Astronaut Candidate Applicant 2002
  • Liked: 2177
  • Likes Given: 5142
I don't much like the idea of moving an Orion CM from SM to lander and back. That's effectively two extra dockings added to each mission. And forces compromises in both modes.

IMO, a light-weight, space/low-g optimized lander cabin, using Orion derived ECLSS & avionics makes more sense, since you only have to deploy it to L1 once with the rest of the re-usable lander.

Mud-room, good idea.  Perhaps even an inflateable like the airlock on the D-TAL concept.

Much prefer the horizontal lander. That ladder looks pretty tall.

You don't have to transfer the MPCV from Earth. You would dock to an already fueled reusable lander ready to go to the Moon and the crew then tranfers over.
Note: My photoshop image of ULA's proposal from here:
http://lunarnetworks.blogspot.com/2010/10/commercially-based-lunar-architecture.html
« Last Edit: 12/05/2011 11:36 PM by Rocket Science »
"The laws of physics are unforgiving"
~Rob, Physics instructor, aviator, vintage auto racer

Offline kkattula

  • Member
  • Senior Member
  • *****
  • Posts: 2508
  • Melbourne, Australia
  • Liked: 10
  • Likes Given: 3
I see a lot of arm-waving on this thread but little or no numbers.There's no way to get a crewed Orion to EML-1 with only one launch of any LV smaller than SLS.

Why is this a problem? Launch Orion unmanned to ISS. Launch crew on ccdev craft. Launch EDS stage. Only EDS stage is time sensative.  2 launches required and 1 launch that was going to happan anyway( the ISS crew rotatation launch). ISS will likely be around till 2028.  The two needed Delta IV launches will cost less than the fixed costs of any HLV and so long as you do 1-2 trips a year this works out fine.

Heck you probably need atleast 4 trips before it makes any sense to use Heavy lift.  In addition you can switch to FH or any future launcher that can lift a 25MT EDS stage in the future. You can swicth to cheaper ccdev in future and so forth. With SLS you have locked your costs in.


Quote
There's no way to get a (non-ZBO) hydrolox crasher stage to EML-1 with only one launch of any LV smaller than SLS.

Why does it have to be hydrolox? You can use storables, you can use SEP(which again offers reuse). Why does it HAVE to be done with 1 launch?

Quote
There's no way to get a hypergolic crasher stage to EML-1 with only one launch of any LV smaller than SLS or Falcon Heavy. Yes you could use an SEP tug, but that would still require several tons of reaction mass. SEP still uses propellant, if more efficiently.

Propellant can be launched either in one launch or launched to a depot or tanker in LEO. If forced to something like a Falcon 9 or a Taraus II could probably launch enough propellant for an SEP stage and again there is a huge launch window here(i.e.  it is going to take months for the SEP to come and go to and from LEO).


These are not problems, merely facts that need to be accounted for with multiple additional launches.

If you think 4 x D-IVH and some additional smaller launches is going to be cheaper than 1 x SLS, then you're probably correct at one mission per year.

At two per year I suggest the balance tips the other way. They should be launching SLS at least 2-3 times per year. It costs very little for each additional SLS launch, and the payloads here are not expensive either: 1 x Orion, 1 x D-IVUS, 1 x Methane tank.

Offline kkattula

  • Member
  • Senior Member
  • *****
  • Posts: 2508
  • Melbourne, Australia
  • Liked: 10
  • Likes Given: 3
So AIUI, the answer to every one of my objections as to why you can't just replace the SLS with existing medium launchers in this proposed architecture is: change the architecture!

Most of theses changes revolve around hypergolics and SEP tugs or ZBO hydrolox depots or EELV Phase I. Fair enough, they would all be workable, but they wouldn't be this architecture.

In the original thread it was claimed this architecture was DOA because it could equally be done without SLS. I think it's pretty clear now it couldn't, without being transformed into something very different.


Offline Jason1701

  • Senior Member
  • *****
  • Posts: 2238
  • Liked: 70
  • Likes Given: 39
In the original thread it was claimed this architecture was DOA because it could equally be done without SLS. I think it's pretty clear now it couldn't, without being transformed into something very different.

While there isn't a drop-in replacement for SLS in this architecture, it does heavily suggest the possibility of alternative architectures employing much of the same hardware without SLS.

Offline clongton

  • Expert
  • Senior Member
  • *****
  • Posts: 10283
  • Connecticut
    • Direct Launcher
  • Liked: 2059
  • Likes Given: 638
Launch Orion unmanned to ISS. Launch crew on ccdev craft.

This is "not smart". Orion is a *manned* spacecraft. If you want to put Orion's crew into orbit then put them inside their own spacecraft and launch them. Going to the extra expense of launching the crew on CCDev spacecraft after their own spacecraft is already in orbit is really dumb. That's like sending a Boeing 737 from New York to Seattle on autopilot and then sending its flight crew to meet it by DC-8 so they can then fly their 737 the rest of the way to Anchorage.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Jason1701

  • Senior Member
  • *****
  • Posts: 2238
  • Liked: 70
  • Likes Given: 39
Launch Orion unmanned to ISS. Launch crew on ccdev craft.

This is "not smart". Orion is a *manned* spacecraft. If you want to put Orion's crew into orbit then put them inside their own spacecraft and launch them. Going to the extra expense of launching the crew on CCDev spacecraft after their own spacecraft is already in orbit is really dumb. That's like sending a Boeing 737 from New York to Seattle on autopilot and then sending its flight crew to meet it by DC-8 so they can then fly their 737 the rest of the way to Anchorage.

Whether or not one has a religious aversion to such an act, it makes sense in terms of total integrated mission cost if the CC launch service costs less than the marginal cost of Orion launching crew.

Offline clongton

  • Expert
  • Senior Member
  • *****
  • Posts: 10283
  • Connecticut
    • Direct Launcher
  • Liked: 2059
  • Likes Given: 638
Launch Orion unmanned to ISS. Launch crew on ccdev craft.

This is "not smart". Orion is a *manned* spacecraft. If you want to put Orion's crew into orbit then put them inside their own spacecraft and launch them. Going to the extra expense of launching the crew on CCDev spacecraft after their own spacecraft is already in orbit is really dumb. That's like sending a Boeing 737 from New York to Seattle on autopilot and then sending its flight crew to meet it by DC-8 so they can then fly their 737 the rest of the way to Anchorage.

Whether or not one has a religious aversion to such an act, it makes sense in terms of total integrated mission cost if the CC launch service costs less than the marginal cost of Orion launching crew.

It doesn't!
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Jason1701

  • Senior Member
  • *****
  • Posts: 2238
  • Liked: 70
  • Likes Given: 39
Launch Orion unmanned to ISS. Launch crew on ccdev craft.

This is "not smart". Orion is a *manned* spacecraft. If you want to put Orion's crew into orbit then put them inside their own spacecraft and launch them. Going to the extra expense of launching the crew on CCDev spacecraft after their own spacecraft is already in orbit is really dumb. That's like sending a Boeing 737 from New York to Seattle on autopilot and then sending its flight crew to meet it by DC-8 so they can then fly their 737 the rest of the way to Anchorage.

Whether or not one has a religious aversion to such an act, it makes sense in terms of total integrated mission cost if the CC launch service costs less than the marginal cost of Orion launching crew.

It doesn't!

I believe that "the marginal cost of Orion launching crew," when the launch vehicle is taken into account, may be greater than the $140-200 million for the CC service, and is certainly greater than the 3/7 or 4/7 of that price that would be incurred if the mission was combined with ISS crew rotation.

Offline deltaV

  • Full Member
  • ****
  • Posts: 1538
  • Change in velocity
  • Liked: 165
  • Likes Given: 480
This is "not smart". Orion is a *manned* spacecraft. If you want to put Orion's crew into orbit then put them inside their own spacecraft and launch them. Going to the extra expense of launching the crew on CCDev spacecraft after their own spacecraft is already in orbit is really dumb. That's like sending a Boeing 737 from New York to Seattle on autopilot and then sending its flight crew to meet it by DC-8 so they can then fly their 737 the rest of the way to Anchorage.
Once the capability to launch crew on Orion/SLS is developed it probably does make sense to use it. The potential savings from launching crew on CCDev comes from not paying for the development and maintenance of the capability. I don't know enough about the potential savings to judge if launching crew on Orion/SLS or CCDev would be better.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 27033
  • Minnesota
  • Liked: 6927
  • Likes Given: 4886
So AIUI, the answer to every one of my objections as to why you can't just replace the SLS with existing medium launchers in this proposed architecture is: change the architecture!
Well yeah, there would be differences since it's designed to require SLS. Obviously, you're not going to use the SLS third stage if you don't have an SLS, right? It looks like you ignored my response to your post where I showed that, yes, a single EELV Heavy launch (i.e. 25mT to LEO, 19.5mT for the crasher stage, 5.5mT for the Xenon) would be enough to place the crasher stage at EML1 (using a SEP-tug), as long as you used the NEXT thruster (which, of course, could be improved upon).

Quote
Most of theses changes revolve around hypergolics and SEP tugs or ZBO hydrolox depots or EELV Phase I. Fair enough, they would all be workable, but they wouldn't be this architecture.
Interesting that you're kind of ignoring that the SLS third stage is kind of doing the same thing as EELV Phase I (i.e. a stretched and heavily modified Delta IV upper stage). You're also ignoring that "this architecture" makes explicit use of SEP tugs.

Quote
In the original thread it was claimed this architecture was DOA because it could equally be done without SLS. I think it's pretty clear now it couldn't, without being transformed into something very different.
Not that different.

If you compare this architecture with Constellation, this architecture looks a lot easier to transition to other launchers. For instance, the crew transfers to the lander from the EML1 gateway. The gateway is like a mini-ISS, with both NDS and Russian ports (they even basically mention Soyuz going to the gateway... you tell me how they plan to do that, but they apparently think it's possible), and all the commercial crew vehicles will be capable of docking with NDS, and both Dragon and CST-100 are probably capable of being modified to be capable of deep space operations (Dragon is probably easier to modify in that regard, since it already has solar panels... and is a lot lighter). So, there could be at least 3 other ways to get crew to the gateway besides Orion (when can we retire the name 'MPCV'?).

The lander itself gets the methane and LOx transfered via the NDS port. It shouldn't care how that methane/LOx gets to EML-1, as long as it gets there and is transferred using the right NDS fluid transfer interface. The descent/crasher stage is the third stage of SLS. Obviously you'd need a different stage to stand in for that one. But that's really one of the only modifications needed to the architecture (by definition if you're not going to use SLS, you can't use pieces of SLS either).

If you have a hydrolox (and possibly methane) depot at EML-1, you can even reuse the crasher stage as well (have it perform a quick burn after separating from the lander to go back to the EML-1 rendezvous point). Or, if your crasher stage uses just methane like I suggested, you only need methane and oxygen and no "ZBO" (methane/LOx is space-storable).

(BTW, I mentioned 370s Isp for pump-fed methane... Boeing says in the presentation it can get to 372s, so I was being a little conservative... also, a methane crasher stage should have a lower tank mass because of methane's much higher density than hydrogen...)

I agree with you that this architecture ISN'T dead-on-arrival just because it leaves open the possibility of not using SLS. That's too cynical for me. I think this really neat architecture would work well with SLS, and I think it's a great double-use of the third stage for SLS.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Tags: