Below are my expanded notes from my Thursday 20 March interview with Altair project office deputy manager, Clint Dorris. I haven’t included everything. There were a couple of facts that came up that warrant further investigation for stories on flightglobal.com
credit: Boeing
NASA received more than 30 proposals for the lander study. Industry should provide their own concepts. We’re onto next design cycle, LDAC-2 for safety features. The minimum functionality lander [already arrived at] may not have global capability.
Altair project is embracing the [Ares V cargo launch vehicle] 10m shroud for the lander, the primary impact being on structures, we can widen and squat the descent module. Doesn’t change subsystems but gets the deck closer to the surface.
Biggest challenge is getting the payload to the moon. We are justifying every functionality and system we add so we do not have to strip down the design later and then buy back functions.
We think it could drive a different safety paradigm, where you don’t assume that two tolerance means its safe.
The Lunar Architecture Team's (LAT) work will impact LDAC-2.
Our design can be indifferent to that [what cargo demands LAT needs]. If we are maximising that capability then we are giving them everything we can with the lander configuration that meets three missions, sortie, outpost and cargo.
The cargo lander has 14,000kg capability to the surface right now, so the regolith mover or the habitats have to fit that 14,000kg.
The [contract winning] companies have been given a one page lander requirements document. It is what the Altair project office team had at the beginning.
Industry is out of phase by one cycle but they are going to evaluate LDAC-1 and propose changes while project office is working on LDAC-2, which is to add safety features to the lander.
We want a scalable, point of departure design to be the outcome of LDAC-2 and industry input.
Dorris didn’t recall the JSC/MSFC Phase b cost estimate. The project office asked JSC and MSFC engineering for pre-Phase A, Phase A and Phase B work estimates, along then lines of how NASA has always done business.
The lander is exclusively a US responsibility but there has been interest from European companies.
We have looked at a drop stage. So have some of our industrial partners. [Boeing has and one of its designs is the embedded image in this posting.]
“Concept I’ve seen more frequently [from industry] is it [the drop tank] would perform [Lunar orbit insertion] burn and then it would drop off. It’s not complete ruled out.”
But when you get to a detailed design they tend to see the drop tank dropped.
Although the study announcement asked how would companies perform the work, during some conversations with industry some wanted to bring drop tank to the table.
Apollo Sages – it has been fantastic. I would like an independent technical assessment by the government and contractor sages. We had a question and answer session with three to four Apollo astronauts. None of them were present at the design review stage.
We are addressing the LOX/LH2 boil off issue. Amount of [Earth orbit] loiter time affects whether it is a problem or not. Looking at a similar mechanism to Ares V EDS, a passive capability, it is still in the trade zone.
Landing areas and scavenging hydrogen issues are in the trade space for surface systems people.
Minor clarification requested: when you say "drop tank" did you intend to say "drop stage" instead?
It seems "drop stage" is the preferred term in NASA today for the old 'crasher stage' concept. I guess crasher stage has too many negative connotations!
I'm glad to see the crasher stage concept hasn't yet been fully abandoned by NASA. I think a drop stage is the logical way to employ a liquid hydrogen fuelled rocket for LOI and lunar descent.
Yes drop tank, drop stage, I think they were interchangeable during the discussion.
Essentially Dorris said that when you get into the detail of the design they become less attractive.
I don't understand the attraction of them at all. You still have to have an EDS that can push all that mass out there. And then you want to junk a chunk of that mass? Why not have a more structurally efficient lander in the first place?
I don't think this 45,000kg boundary is going to last long either. If you look at Dorris' space exploration conference presentation the mininmum functionality designs for the three mission concepts hit 45,000kg real easy, and he admits that that design can't go every where on the Moon, no 'global capability' to use the jargon, and they want to add systems, more mass, to make the lander safer.
I am beginning to feel that the current architecture is not going to be able to efficiently deliver all the equipment and crew to the Moon's surface.
If built, the Ares V would be the largest rocket ever made by the hand of man in all history & it still wouldn't do the job.
The only (non drop-stage) hydrogen-fuelled lander that impressed me is the Lockheed-Martin dual-axis thrust horizontal-lander concept.
To me it is the lander design details that make a drop-stage appealing. A drop-stage can exploit lighterweight construction, use simpler non-throttling engines, and employ a larger expansion-ratio nozzle to wrest out every bit of ISP.
Most of the hydrogen enginned cargo landers NASA considered during the Apollo-era used drop-stage design. Without a drop-stage, the huge prop tanks of low-density hydrogen usually result in a towering lander with heavier landing gear, a higher center of gravity and cargo perched way way up above ground level.
Heck, even without hydrogen a drop-stage is appealing; the efficient Surveyor lunar probes used a solid-propellant drop-stage, the original Apollo moon-direct was going to use a drop-stage as was the later Soviet manned lunar lander.
Glad the crasher stage concept hasn't been dropped it's a good concept for reducing mass.
With a drop stage you don't have to decelerate the tanks and engines needed for LOI all the way to nearly zero velocity for landing.
14,000kg is starting to get to a useful payload and could land a half sized bigelow BA330 or a full sized sundancer.
Which would be an expandable module with about 160 cubic meters of volume once deployed.
I'd go with the transhab design over conventional aluminum one it offers a better mass to volume and two it's over twice as strong and resistant to MMOD damage.
14 metric tons also is enough to land a robot/truck like Athlete or a good pressurized rover.
Other stuff they really need to look into is getting away from hydrogen on the lander it's self and using a solar/nuclear electric ion or vasimr tug for transporting bulk cargo from LEO to the surface of the moon.
Cargo doesn't have to take a 3 day trip it can take six months if needed.
Such a tug could reduce the cost of maintaining a base by an order of power by allowing use of a smaller LV on non time critical cargo like hab sections,bulk water and heavy equipment.
IE a delta IV of Falcon 9-H can be used send the same 14 tons to the lunar surface.
With the pervious design it seemed like even Ares V would not be enough and they might have had to look into sea dragon or rombus just to make their payload budget.