Lockheed Martin reveal their three Lunar Lander Concepts

[impulse]

Yah about those ceilings... they come essentially "for free" in a sense. The top element is like the top of a bagel- it contains all the air handling, lighting, power and data distribution, water etc. It has a domed upwards shape and the apex is dictated by structural efficiency- making a flat pressurized structure is inefficient- at least at large dimensions. <br /><br />Without my immediate access to the diagrams which outline the architecture concept it is a bit difficult to discuss it but here are some fundamentals:<br /><br />The key thing about exploration transport is that most of the mass we have to move is propellant and most of that is LO2. This is often lost on a lot of folks. So the thing we need the most of has almost no intrinsic "value". It is not a super-complex spacecraft. We need to become absolute experts at moving and storing propellants. Without this you aren't going to Mars and your lunar explorations will be pretty feeble.<br /><br />Storing cryogens can be either hard or easy- you get to pick. The last place to put a cryo depot is in LEO. There is not only the normal solar irradiance but also earth albedo and IR- both of which are significant. Aerodrag is nonzero as well as gravitational/tidal effects. Once you pick an orbital plane you are also quite restricted in when you can go to the moon thereafter. It is far better to burn out of LEO and just get to cislunar space as soon as possible. In other words, you must execute a 3100 m/sec burn to get out of LEO and another 1100 or so for LOI so it is best to do that immediately and reduce the mass of cryos that must be stored. It is far easier to maintain reasonable boiloff rates with reduced masses and in lower heating environments. <br /><br />You don't have to eliminate boiloff- in fact you need to have some. If you plan on staying near the moon you must count on using up stationkeeping propellants. Fortunately it turns out that GH2 makes a wonderful propellant- so we use it exclus

 

[willpittenger]

Low ceilings have their own problems. My sister's ex was 6' 4". He was always ducking around my parent's old home. If he were to move back in with my sister again, he would probably get a very cramped neck. The ceilings at her new home are roughly 7' with doorways about 6' 3" or so.<br /><br />Besides, things like ceiling fans are required to be a certain distance up off the floor. (Now if you have always wanted to loose your head, I suppose you could try mounting a fan lower.) <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[willpittenger]

<blockquote><font class="small">In reply to:</font><hr /><p>You don't need jetways, if that's what you mean. The whole idea would be to have the vehicle in an enclosed, pressurized hanger where it could be serviced and payloads could be unloaded and loaded with minimal complications.<p><hr /></p></p></blockquote><br />The hanger concept only works after you have delivered a lot of modules -- starting with the hanger, which would be amongst the last base components to go. (Any servicing the lander gets would be minimal. That is why you would only get something like 5-10 flights per lander.) For smaller operations, the lander stays outside. You could have the lander land on a movable pad. The pad moves out for landings and take-offs. You then move it back in to dock. However, you still need to dock somehow. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[gunsandrockets]

Fascinating stuff!<br /><br />First things that pop to mind:<br /><br />1) Cold-gas GH2 thrusters for stationkeeping.<br /><br />I'm really surprised that scheme has as high an ISP as you say, I would never have guessed it. It makes me wonder why the ISS wastes the hydrogen generated as a byproduct of the Elektron airmaker rather than store the hydrogen for stationkeeping purposes.<br /><br />2) Parallel flights of the Orion and LSAM to moon LLO.<br /><br />Aha! I suspected something like that had to be the case. Now the 'pie-wedge' lifting body CM that made a splash in Popular Mechanics with it's associated MM and PM makes much more sense to me. The Propulsion Module really had me scratching my head as I tried to figure out how all the various masses for various propulsion events worked out. Refuelling in LLO scrambles all those assumptions and makes the cofiguration sensible.<br /><br />3) LLO cryopropellant depot<br /><br />Very interesting. I wonder why LLO instead EML-1 though? And how bad is the boil-off?<br /><br />5) 75 tonne LEO payload Atlas derived launcher<br /><br />It's not really accurate to describe this as a medium launcher now is it. Even if a little on the lower end of the scale this is really a Heavy Launch Vehicle.<br /><br />6)Architecture applicability to Mars?<br /><br />The scheme you describe looks nice for lunar missions. Well done!<br /><br />But how would you apply it to a Mars mission? In all fairness I think understanding the best way to get to Mars first requires filling important gaps in our knowledge of Mars and of human survival in long duration spaceflight.<br /><br />For example, is permafrost sitting as little as 1m below the Martian suface at 40+ degrees lattitude as currently thought? Is there harvestable ice present in the moons of Phobos or Deimos? If so that could radically alter the best methods for travelling to Mars.<br /><br />Then there is the gravity issue. How long can a human remain healthy under prolonged conditions of weightless

 

[barrykirk]

One of the more important factors involved in ISP is the MW of the exhaust gas. The lower it is, the higher the ISP.<br /><br />It's hard to get much lower than the MW of H2.

 

[mrmorris]

<font color="yellow">It makes me wonder why the ISS wastes the hydrogen generated as a byproduct of the Elektron</font><br /><br />I've seen the question brought up in various threads about why the hydrogen gas from the Elekton is simply vented to space rather than being stored in a tank at the ISS. I suspect that technically, maintaining the gas as LH2 in LEO is more challenging than people tend to assume (most things about spaceflight *are*). However, I'm going to ignore the technical end and look at this from a volume standpoint. If it were being saved... how much would be generated?<br /><br />Water is about 18 grams per mole, and 1000 grams per liter.<br />Water usage on the ISS is about 1.8 liters per day per crewmember. <br />H2 is 2 grams per mole.<br /><br />So for three crewmembers, the daily H2 production of Elekton assuming <b>all</b> of this water were to be reprocessed by Elekton would work out as follows:<br /><br />One liter of water is ~55.55 moles of H2O (also 55.55 moles of H2 for that matter).<br />Each liter then contains 111.1 g of H2.<br />Given a crew of three, the daily H2 production would be about 599.94 g of H2.<br /><br />Let's work out the production-to-date numbers assuming (wrongly) that we'd had three crewmembers on-board since the first crew arrived on November 2, 2000 and that Elekton were in place and generating H2 from day one. I'm going to be lazy and give them until Nov 2 of this year to make more hydrogen so that I can simply use 6*365 to get a count of days (yes, I'm ignoring leap years). This would mean that the Elekton would have produced 1314 kg of H2 gas from then until a couple of months from now. Of course there hasn't always been three crewmembers, and there are other holes in the assumptions (like this assumes zero boiloff losses), but we'll use the number as a high figure anyway.<br /><br />1300 kg of H2 seems reasonably hefty... but it t

 

[scottb50]

Where I differ with your plan is handling the propellants and having to send a new descender for every mission. I have repeatedly pushed using water for two reasons, first it is simple to contain, easy to handle and presents no boil-off problems. Second there is more than enough Solar power availability in LEO and on the moon to produce LH2 and LOX as it is needed eliminating the need for long term cryogenic storage. <br /><br />I fully agree LH2 and LOX should be used exclusively alllowing common thruster and engine designs throughout the system. I would use the same main engines on the upper stage of a launcher as I would use on the moon transit vehicle and the Lander/Ascender Vehicle. If you use the propellant tanks from the upper stages as Modules to build LEO facilities, transit vehicles, lunar landers/ascenders as well as lunar surface facilities you have a lot more useful payload capability. You would still need to take water to the moon, but if you use the same Modules as the upper stage uses they can be used to expand the station or packed with return samples or crews and sent back to LEO.<br /><br />I still think with a system like this cyclers from LEO to LMO and back to LEO would be economical. It would take a lot of propellant to enter LEO on return, but if you eliminate hardware losses the only real expense is bringing the water to LEO, something that can be done with virtually any launch system. This would also simplify the manned launch system, it would be limited to Earth, LEO missions only, no need to carry it along to the moon or Mars when you have upper stage Modules that can be outfitted for passengers and crew. <div class="Discussion_UserSignature"> </div>

 

[josh_simonson]

As an advocate for fuel depots and sustainable exploration, I love this plan. However I don't think that LLO is the right place for the first fuel depot - it should be in LEO, dispite the slightly worse thermal environment (you mention drag too, but that's equivalent to stationkeeping in LLO). <br /><br />There are two reasons for this, first being that it will be far cheaper to deploy such a depot in LEO for demonstration purposes. NASA will probably require such a demonstration for them to take this approach seriously. <br /><br />Second is that LEO is available to wider range of launch vehicles than LLO is, especially smaller ones and re-useables, and fuel delivery missions are simpler. A LEO fuel station allows fuel to be launched on the cheapest available vehicle while the expensive hardware is launched on the most reliable vehicle. Since cost an reliability are exclusive to a large extent, fueling for TLI in LEO will be a good cost reduction tool. Fuel delivery could be carried out by the international partners, who already have or are close to having LEO delivery spacecraft. This is a great way that they can participate without falling afoul of export restrictions.<br /><br />Having two depots also creates an opportunity to provide fuel transport from one to the other if it can be done cheaper than LH2/Lox stages, such as SEP. This again provides cost savings.<br /><br />Last, a LEO depot could serve as a replacement for the ISS after the ISS is retired, not so much a human tended behemoth, but a place where experiments could be conducted that would have some human interaction occasionally available.<br /><br />Another minor suggestion, make sure your depot prominently features a robotic arm and an airlock. The robotic arm greatly simplifies docking, construction, and EVAs, as well as providing inspection capability to enhance safety. JAXA will soon demonstrate arm-assisted docking on the ISS (if no-one else does), making that another 'proven' cost saving tec

 

[gunsandrockets]

"Version 1 is the one that I (as the designer) really favor...Plus if I was an astronaut I would rather fly V1 than some hokey 1960's spider thing. If you do the vehicle dynamics work that simple machine is amazing- almost scary capability in maneuver ( you can do radical pitchup loop maneuvers if you are so inclined) and yet quite stable for landing."<br /><br />For Version 1 of the dual-axis thrust lander to minimize attitude-rotation issues and place the windows in the right position for observation of the final approach and landing the main descent engine must apply enough delta V to fully stop movement (and maybe even a little bit more) before transitioning to the other thrust axis. Absent that change in flight direction the lander would have to, at the minimum, do a pitch-down maneuver of 90 degrees while transitioning from the initial thrust axis to the final thrust axis.<br /><br />Since by necessity Version 2 of the dual-axis thrust lander (with the lunar-crasher-stage) must drop the descent stage prior to hover, the Version 2 lander is stuck with the added risk of the pitch-down maneuver. So I don't think the dual-axis-thrust lander is practical with a crasher-stage; but a crasher-stage type lander is very practical if the lander's upper-stage thrust is in-line with the crasher-stage. <br /><br />An in-line thrust lander increases abort options when the lander is docked with the Orion. The payload advantage of a crasher-stage type cargo lander compared to other cargo lander designs could make it very appealing to NASA. A crasher-stage manned-lander also has the advantage of not littering the landing area of a moon-base with expended descent-stages.<br /><br />I understand that with the Version 1 lander leftover descent-stages are assumed to be a feature, not a bug. But requiring a lunar base be built up from leftover descent-stages could unneccessarly constrain the design of the lunar base.<br /><br />Even though I think NASA would lean more favorably to a

 

[gunsandrockets]

"Plus if I was an astronaut I would rather fly V1 than some hokey 1960's spider thing. If you do the vehicle dynamics work that simple machine is amazing- almost scary capability in maneuver ( you can do radical pitchup loop maneuvers if you are so inclined) and yet quite stable for landing. Visualize a UH-60 landing and you have it right. Now watch how those Blackhawk pilots maneuver and you have some idea of what this thing can do. Much of this design was influenced by my discussions with helicopter pilots in New Zealand who do an extraordinary amount of flying to unprepared and rough terrain due to the vast roadless areas they have. "<br /><br />Speaking of helicopters, have you considered helicopter-style landing skids for landing gear? Such landing skids can also be combined with small wheels (like the small wheels illustrated on the dual-axis thrust lander's small landing struts). Landing skids can be very lightweight, appropriate for supporting the low weight of a lunar lander, and still provide a large stable footprint for touchdown. <br /><br />I first saw skids suggested in the book "Chariots for Apollo" which gave a detailed story of the Apollo lunar lander program. It seems the Lunar Module's landing gear was overbuilt because the engineers kept getting horror stories from astronomers about possible lunar surface conditions. The book said that if the engineers were to design a lander informed of the true lunar conditions they would have preferred to use lightweight helicopter-style landing skids instead.

 

[gunsandrockets]

Confirmation from nasaspaceflight.com of the Centaur based cryogenic lunar architecture the poster 'impulse' was talking about so long ago...<br /><br />http://www.nasaspaceflight.com/content/?cid=5063<br /><br />

 

[JonClarke]

I would hope that NASA would be convinced by the advantages from an access and internal layout perspective of a dual axis lander over the LM style layout.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[docm]

We can only hope. It makes a lot of sense. <br /><br />That said I'd still like to see an Eagle running around the moon, sort of a "Dual-Axis on steroids"? <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> </div>

 

[gunsandrockets]

[That said I'd still like to see an Eagle running around the moon, sort of a "Dual-Axis on steroids"?]<br /><br />Ain't no piddly RL-10 in an Eagle's tail, more likely an NTR!

 

[gunsandrockets]

[I would hope that NASA would be convinced by the advantages from an access and internal layout perspective of a dual axis lander over the LM style layout.]<br /><br />If other information can be trusted, it appears the dual-axis thrust configuration is out of the running for the NASA lunar lander. But only one of the half-dozen configurations which have made the final cut is close to the old spider style configuration. All of the other configurations try to ease surface access and one of them is even a horizontal lander! <br />