Alan Boyle has a pretty good article over on Cosmic Log about the Lunar Lander Challenge as well as the Artemis Lunar Lander (aka LSAM) that NASA intends to field in the coming years. I think the fact that Northrup is sponsoring the event highlights the “furry dinosaurs” (“mammal-friendly dinosaurs” maybe?) trend I was mentioning in a previous post.
The article makes a good point about a better approach to doing lunar missions: sending both manned landers as well as resupply landers, instead of trying to do each manned mission using a single lander. The whole idea that you should design your lunar lander vehicle to also function as a 6 month hotel is kind of silly in my opinion. Transport vehicles in a pinch can serve as emergency shelters, but if you’re planning on going to stay, send enough supplies to build a base camp or settlement. Along with your crew/passengers, send several landers carrying the long-duration habitats (possibly initially using Sundancer modules to provide housing before enough in-situ manufacturing has been figured out to build the rest of the structures out of local materials). Much better than trying to make each landing mission a self-contained base camp.
I’m still not a big fan of splitting the lander and ascent stages like they’re planning. I’d much rather have a single-stage reusable system, as it’s a lot easier to make such a system flexible, and able to benefit from future ISRU propellant supplies if they become available. Even if you’re talking about staging out of L1 or L2 instead of lunar orbit, the Delta-V is only about 5km/s, which is just about the same as a round-trip from LEO to lunar orbit and back (with partial aerobraking to return to LEO instead of direct to the surface). It’s a bit of a challenge, definitely tougher than what we’re doing at the moment at MSS, but not unrealistic at all, especially if you use propellant combos like LOX/Kerosene, LOX/Methane, or LOX/Propane. Anyhow, I’ll have to give some more of my thoughts and musings about real lunar lander design at some future date.
I also like the comment near the end:
Davis acknowledged that the teams targeting the challenge could someday be Northrop Grumman’s competitors – or its partners. “What I think is really remarkable about these entrepreneurs is that they’re not constrained by traditional practices,” he told me. “In some sense, they don’t know what it is that they can’t do.”
I think this quote makes two good points. First off, there might actually be something to be gained by more traditional aerospace companies teaming up with emerging space companies for developing lunar landers. Both the dinosaurs and mammals have their strengths and weaknesses, and working together as partners might really make sense (for both parties). The second point was that “not knowing what you can’t do” is often useful, because many times the “conventional wisdom” ends up becoming obsolete over time. One example of this is the fact that conventional wisdom says that deep throttling of liquid biprop engines is extremely difficult, however you’ll notice that one of the problems that neither MSS or Armadillo really had was with getting the engines to throttle stably.
Anyhow, I’m rambling a bit, but I think the overall thrust of the article was good, and I really hope that these prizes end up serving as a catalyst for strengthening the emerging base of new VTVL companies, and that those companies can help establish a robust commercial lunar transportation system. Oh, and I also hope that I get to continue to get to participate in the adventure.
Jonathan Goff
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Jon, it occurs to me (as a non rocket-scientist type) that EML-1 or EML-2 are the only locations that makes any sense whatsoever for a extended program of repeated lunar access.
LEO? Your LSAM either needs an aeroshell or fuel for propulsive orbital capture. That equal mass.
LLO? Choosing the inclination for parking a single stage LSAM in low lunar orbit will always result in serious compromises and will make difficult the timing of Earth launches to meet up with an LLO LSAM.
EML-1 and EML-2 have 24/7 access to every point on Earth and every point on Luna. No launch window issues, ever.
Also, isn’t the moon “lopsided” (uneven mass distribution) which causes long term low luanr orbits to degrade in ways that are difficult to predict? Keeping an LSAM in a chosen low lunar orbit for an extended period may not be a trivial undertaking.
Is precession the right term?
My understanding is that an LSAM parked in LLO that passes over a lunar base will see a gradual shifting in its orbit and 30 or 45 days later it will no longer be at an inclination that allows access to the base without doing plane change engine burns.
Park it an L point and it will stay just about exactly where you leave it.
= = =
One Bigelow crew quarters (Sundancer?) plus one FBG-2 class module plus a multi port docking module and you have yourself an EML-1 transfer station.
Fly to EML-1 with Soyuz or equivalent SpaceX vehicle, change trains to that single stage LSAM and you have access to the entire Moon for a fairly low incremental cost per mission.
PS:
I recall a discussion with Rand Simberg from a while back where he said that single stage fully reuseable LSAMs only made sense if you have access to in situ lunar fuel.
That observation makes a great deal of sense to me. Unless lunar oxygen is to be made a high priority item, staging the LSAM and leaving descent modules behind probably is the way to go.
And, I wrote lunar oxygen on purpose.
Harvesting lunar H2 would be terrific but its only ~12% or ~15% by mass of the 2H2 + O2 combustion equation and you can harvest oxygen from just about anywhere on the Moon, not merely polar cold traps.
Bill,
Wow. You do like long comments, don’t you? 🙂
Jon, it occurs to me (as a non rocket-scientist type) that EML-1 or EML-2 are the only locations that makes any sense whatsoever for a extended program of repeated lunar access.
Well, if you mean that “L-1 or L-2 are the only locations that make sense for basing your lunar lander out of” then I’d mostly agree. The reality however is that you need both LEO infrastructure and Lunar orbital (whether Lagrangian or not) infrastructure to make a real transportation system work. As you say, you wouldn’t want to use the Lunar lander for trips back to earth–you would want a more purpose-built transfer vehicle that was kitted out for aerobraking and such, not kitted out with landing gear, etc. Now, having the ability to bring the empty lunar lander back to LEO or to the earth’s surface for overhauls, upgrades, or repairs that are too difficult to do in L-1/L-2 or on the lunar surface might be useful. But you’d probably accomplish that by having a lunar transfer vehicle that could enclose the empty lunar lander and protect it during aerobraking and/or reentry.
Now, near-term, before we actually have actual permanent infrastructure in lunar orbit or the lunar lagrange points, LLO isn’t entirely a bad option. There are tricks you can do with highly elliptical lunar orbits that get you many of the benefits of the lagrange points at a lower cost, but LLO is more unstable longterm than the Lagrange points, so once you have a station there, you’d probably want it at one of those two locations.
Fly to EML-1 with Soyuz or equivalent SpaceX vehicle, change trains to that single stage LSAM and you have access to the entire Moon for a fairly low incremental cost per mission.
Alas, it will be a long time before it’s *that* easy. The reality is you have a lot of logistics you have to deal with for stuff like the lander propellant and such. Longer term it will aproximate that more closely, but long before it reaches that point, we’ll have long since abandoned Soyuz’s and ELV launched capsules for manned space access.
~Jon