Author Topic: Can SLS/Orion carry a LITTLE lunar lander with ascent vehicle?  (Read 3179 times)

Offline carmelo

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So the key is a new service module (and of course a new LEM)?

Online MATTBLAK

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I'm unsure of the architecture of the Orion Service module these days - most of the documentation I have for the SM is from the Constellation era. It's a relatively 'stumpy' design, so I'm not sure if a mere propellant tank stretch would work without a big moldline change.
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Offline ncb1397

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I'm unsure of the architecture of the Orion Service module these days - most of the documentation I have for the SM is from the Constellation era. It's a relatively 'stumpy' design, so I'm not sure if a mere propellant tank stretch would work without a big moldline change.

If you needed the stack to carry more propellant, why would you stretch the service module instead of just adding more to the lander from the beginning? The SLS Block 1B's universal stage adapter provides 286 cubic meters of volume, enough for a couple hundred mT of propellant.

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Well, yes. The dry unfueled mass of the Apollo LM was less than 5 metric tons, or 10,000 pounds. And that was a bare-bones vehicle! It's 10 tons of hypergolic propellants was only just sufficient for the job. The Constellation Altair baseline - though the goalposts moved a few times - was a 40+plus ton vehicle. And that was a LOX/LH2 powered craft that was to carry enough propellants to insert itself and an Orion into Lunar orbit. If we assume that a baseline modern LM was to be sent to the Moon separately on another SLS 1B, which apparently can send 39 tons on TLI, then it's probable fueled mass would be in that 39 ton neighborhood. Assuming that it would be a hypergolic fueled LM that only needed to insert itself into LLO, then it's propellant load for that - plus descent/ascent duties would be about 27 tons.

This is assuming a modern composite, low mass unfueled structure of about 10 or 11 metric tons for a crew of 4. A crew of 2 with this class of vehicle would be easier to achieve. Using LOX/Methane for the LM would yield better results, but not a massively better difference. So; that's the design goal for a low technology risk, understood LM concept - a crew of 2 or 4, throttling hypergolic engine(s) and an all-up fueled mass of 37-to-39 metric tons. This craft could be evolved to be fully reusable, staging from a Lunar Orbit space station. That way, a Command Module either Orion or some other commercial craft could transit crews to the Station and it's Lander. And as others have said; propellants for the Lander can be sent by Commercial suppliers or brought as a refueling pod by the Command Module.
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