Sunday, September 22, 2013

SLS for Return to the Moon by the 50th Anniversary of Apollo 11, page 5: A 90+ metric ton first launch of the SLS.

Copyright 2013 Robert Clark

 Finally someone at NASA acknowledges that the Block 1, first version of the SLS to launch in 2017 will have a 90+ mT payload capacity not the 70 mT always cited by NASA:

SLS Dual Use Upper Stage (DUUS).

 This is important since it means we will have the capability to do manned lunar landing missions by the 2017 first launch of the SLS.
 As discussed in the blog post SLS for Return to the Moon by the 50th Anniversary of Apollo 11, page 2: Orion + SEV design, a 90+ metric ton launcher means we can even use the Orion as the crew capsule. This is important for political reasons since the great expense spent on it means there would be a great desire among its supporters to see it be used. 
 There also is a preference at NASA for the departure stages from the lunar surface and from lunar orbit to use hypergolics, which have the surety of igniting on contact. Then another advantage of a 90+ mT SLS is that the heavier hypergolics can be used for these stages rather than the lightweight hydrogen-fueled stages I suggested in that blog post. In an upcoming post I'll show using existing hypergolic stages how we can get a lunar landing mission at less than 90 mT to LEO.
  For any of these methods it is important to use currently existing stages rather than developing them from scratch. A big reason that NASA ruled out a return to the Moon was because of the assumption that it required the development of new Altair-sized lander at a $10 billion development cost. But the need for a 45 mT Altair-sized lander is provably false as shown by the Apollo lander at one-third the size. And simply adapting already existing stages reduces the cost to a fraction of that needed for an Altair.
 So NASA is making expensive policy decisions such that we can't return to the Moon based on provably wrong assumptions. One is that the Block 1 would only have a 70 mT payload capability and so would require an expensive upper stage to increase the payload to do lunar missions, and another is that a lunar lander would require an additional $10 billion development.
 In fact, once you recognize the, obvious, fact that a lunar mission does not require an Altair-sized lander then so many possibilities become apparent. We did not have the great variety of existing launchers back in the Apollo days that we have now. If you allow your lander to be at or smaller than the Apollo lander then there are a variety of launchers that could be used for lunar missions, not just the SLS. And since they are already existing, or will be soon such as the Falcon Heavy, there would be no huge, multi-billion dollar development cost to use them. 
 So likewise also is the case for the in-space stages needed. They are already currently existing and would require relatively minor adaptations to be used for a lunar lander, for example.
 Indeed we could do manned lunar missions for what NASA is currently paying the Russians to send a crew of 3 to the ISS. The implications of that are jarring: we could have regular manned flights to the Moon for the same amount as what we are currently paying to send regular manned flights to the ISS.  And since the cargo flights to the Moon would be similarly low cost and using Bigelow style lightweight habs would allow a habitation module to be sent to the Moon on a single flight, we could have a manned lunar base for the same amount as what we are paying to sustain the ISS.
 All this comes from simply the mental reset that a lunar mission does not require the $10 billion Altair.
 Free your mind, the rest will follow.

    Bob Clark

Note: thanks to M. Moleman for discussing the NASA report "SLS Dual Use Upper Stage (DUUS)" on his blog.


  1. The size of the lunar lander is set by the mass you want to land, more than any other factor.

    It needs to be staged only if there is a max size limit, as there was in Apollo because of the one-mission/one-launch technology limitation back then, that is nothing but a preconception today.

    Fundamentally, the lander can be a one-stage device on the moon, if only you allow it to be a bit bigger. That it what makes reusability possible.

    I have not seen much discussion of what actually is to be landed in a return to the moon, coming from NASA. Instead, we saw an Altair lander concept sprung upon us. The fundamental mission to be accomplished was never explained.

    Apparently, the only folks discussing the fundamental mission to be accomplished are folks like us on these sites. Opinions vary considerably, so I'm not sure what it really is.

    A very small staged, one-shot lander could reprise an Apollo flags-and-footprints mission, augmented by better sample return. But is that what we really want to do? I don't think so.

    A moon mission involving a base or research station would require landing much heavier payloads. That's a inevitably bigger lander, so it can be one-stage, and potentially reusable. In fact it ought to be reusable, because it will need to land multiple payloads to establish that base or station.

    That kind of mission could be flown with multiple launches of rockets we have or will soon have, whether or not SLS ever flies. We know an awful lot about rendezvous, docking/assembly, and EVA operations than we did during Apollo. Things are vastly different now.

    Something like a Falcon Heavy could fling a manned capsule to lunar orbit. That one or any of today's Falcon-9, Atlas-V, or Delta-IV could fling propellant tanks and payloads-to-be-landed one-way to lunar orbit for the lander.

    If we go with a big reusable lunar ferry for the lander, it could probably be assembled in low Earth orbit from a couple of Falcon-Heavy shots, and fueled by a third, then shoot itself to lunar orbit, manned or otherwise.

    That's how you put a big base or station on the moon, without a huge gravy-train development program for a giant rocket or any other piece of hardware.

    If there is a development to be done, I would develop a "supple space suit" out of the mechanical counterpressure approach. But, I would turn it into vacuum-protective underwear, worn with a variety of different outer garments suited to the various tasks at hand.

    To take on a mission that makes sense requires only an act of public will: we have to get the politics out of the government space program, so that NASA looks more like the NASA of 1960. Then your lead agency people can actually finally do things that make sense, starting with basic mission objectives and strategy at the top. Right now decisions are completely driven by who made what prior tinkertoys in which congressional district. That's utter nonsense.

    As Mark Twain said, "Politics is really show business for ugly people".


  2. I appreciate your comments Gary, and thanks for the link Bob.

    A one-way mission to the lunar surface could land yet more payload. I'm not talking a manned mission here but rather a telerobotic ice harvesting mission with the goal of producing enough propellant to initiate a sustainable cis-lunar transportation system.

  3. Bob: Take a look at my 9-24-13 post over at "exrocketman". -- GW

  4. "Note: thanks to M. Moleman for discussing the NASA report "SLS Dual Use Upper Stage (DUUS)" on his blog."

    No problem!

    Though, as for the post itself is concerned, I don't think Altair was completely unnecessary. Apollo had to support 2 people for 3 days, Altair had to support 4 people for 7 days, which is 6 man days versus 28. It's a big difference and results in a much bigger lander. It also had to do the LOI burn for the entire stack, making it even bigger. I do think the use of either a cargo lander or two separate HLV launches with docking in LLO would have been a much better idea than the one Constellation settled for, and the size of Altair could easily have been reduced to 20-25 tons with a different architecture.


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