With a fuel depot infrastructure the single stage lander would not be too large for SLS or even a smaller vehicle like New Glenn or Falcon Heavy as it could act as it's own departure stage.
The deck of charts are now publicly available here: https://www.nasa.gov/directorates/heo/nac-heocBut these appear to be the most relevant to the current discussion (these are from Crusan’s slides)
Hypergolics do have one advantage they can be easily stored long term in space so a SEP tug could be used to take propellant from LEO to where it's needed.But it doesn't lend itself to ISRU like hydrogen or methane and LOX which does make it kind of a dead end for Mars and beyond.
Anybody here with inside knowledge on accurate numbers for the ESM?Quote Its dry mass is 3.5 metric tons and it can carry 8.6 tons of propellant. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170009574.pdf
Its dry mass is 3.5 metric tons and it can carry 8.6 tons of propellant.
Long-term storage of liquid hydrogen, a deep cryogen, would be problematic, but moderate cryogens like lox and methane are sometimes referred to as "space storable." And you wouldn't have to worry about them freezing.
1NASA seems think storing LH is big problem while LM ( Lunar lander and Mars orbiting base station) and ULA (ACES Upper Stage) don't see any problems storing it for weeks to months without cryocoolers. Its about time NASA funded a demo mission by one of these companies to prove it one way or another. Besides higher ISP performance of LH LOX it is also fuel we have lot of flight experience with. There is no flight proven methane boosters or USs.
A 6 month lunar surface mission aiming to have at least 1 litre of hydrogen at the end of the test. An additional design aim to lose less than half of the say 2 litres that were delivered to the Moon.
Quote from: TrevorMonty on 12/11/2018 02:42 pm 1NASA seems think storing LH is big problem while LM ( Lunar lander and Mars orbiting base station) and ULA (ACES Upper Stage) don't see any problems storing it for weeks to months without cryocoolers. Its about time NASA funded a demo mission by one of these companies to prove it one way or another. Besides higher ISP performance of LH LOX it is also fuel we have lot of flight experience with. There is no flight proven methane boosters or USs.A 6 month lunar surface mission aiming to have at least 1 litre of hydrogen at the end of the test. An additional design aim to lose less than half of the say 2 litres that were delivered to the Moon.Probe likely to include hydrogen, flask, sun shield, instrumentation, (insulated) legs, own radio link, controller, solar panel, (heated) batteries and optional cryocooler. Optionally the transmitter and electronics may be switched off during the lunar night to save power.CLPS can deliver the payload to the Moon. Electronics that works at cryogenic temperatures was developed for the James Webb Telescope. For example https://www.nasa.gov/centers/goddard/news/topstory/2008/jwst_shakerattle.html
It is not immediately clear to me that taking methane down, and just using it with ISRU oxygen is not a better plan than all of the infrastructure that goes into finding, extracting water and storing it as hydrogen, then using it in comparably bulky tanks.
Quote from: A_M_Swallow on 12/11/2018 04:51 pmA 6 month lunar surface mission aiming to have at least 1 litre of hydrogen at the end of the test. An additional design aim to lose less than half of the say 2 litres that were delivered to the Moon.Because loss is a surface phenomena, not volume, a litre of hydrogen has with the same tank technology, a tenth of the storage duration of 1000l.So, you want to scale down the duration unless you actually want six month long hydrogen missions with a kilo of fuel.
Quote from: Markstark on 12/08/2018 05:36 pmThe deck of charts are now publicly available here: https://www.nasa.gov/directorates/heo/nac-heocBut these appear to be the most relevant to the current discussion (these are from Crusan’s slides) I don't think that adding all the delta-V's is correct. Each stage does not perform TLI twice!
Quote from: speedevil on 12/11/2018 05:25 pmIt is not immediately clear to me that taking methane down, and just using it with ISRU oxygen is not a better plan than all of the infrastructure that goes into finding, extracting water and storing it as hydrogen, then using it in comparably bulky tanks.The expensive part and most energy intense is splitting hydrogen from oxygen, its waste throw H away once hard work has been done. Cooling should be easy with access to deep cold of water bearing craters.
Hey Steve - which case are you referring to in the chart? The places where I see TLIs listed twice are in instances where two rockets involved (1 crew, 1 cargo). So the multiple TLI are for the multiple rockets rather than # stages. At least that's how I read it. But I could be misreading it. Thanks!
Considering how changing an in-space stage and service module into a lunar lander would already warrant many changes to the design anyway, like new avionics and landing legs, slightly stretching the tanks to meet additional delta V requirements would be a minor change.
Quote from: TrevorMonty on 12/11/2018 06:09 pmQuote from: speedevil on 12/11/2018 05:25 pmIt is not immediately clear to me that taking methane down, and just using it with ISRU oxygen is not a better plan than all of the infrastructure that goes into finding, extracting water and storing it as hydrogen, then using it in comparably bulky tanks.The expensive part and most energy intense is splitting hydrogen from oxygen, its waste throw H away once hard work has been done. Cooling should be easy with access to deep cold of water bearing craters.Apologies for being unclear, I was referring to sourcing O2 from regolith, not water.For the case of methane (or O2), a storage vessel that ends up with 50% of the total initial mass after 6 months is utterly trivial and off the shelf, for containers over some 30l.An off-the-shelf dewar will get you that performance, for around $1000 shipped. You will need a simple sunshade.No cryo refrigeration, no development.
Quote from: Coastal Ron on 12/08/2018 06:37 pmI guess I'm not understanding why NASA wouldn't want to make the entire lunar lander reusable. What's mentioned in the presentation: If you use hypergolic propellants a single stage lander, even when using a space tug for lunar orbital transfers, would be too heavy and physically large to lift on commercial launchers and can't be co-manifested on SLS.Seeing how NASA limits itself to hypergolics, it seems more likely that NASA instead wants to minimise programme risk and development cost, foregoing the technologies I mentioned earlier that would enable full reuse. With only partial reuse, SLS only flying once a year and no potential for ISRU, there is no actual plan to actually do frequent surface sorties that would justify the added development costs for fully reusable lander. In other words there is no plan to actually turn this into a serious way to do lunar exploration and settlement.
I guess I'm not understanding why NASA wouldn't want to make the entire lunar lander reusable.
<snip regolith oxygen extraction question>To extract O, the regolith is heated with H gas. O bonds with H forming water, with iron being one of by products of this reaction. NB this how to produce iron on moon. Water now needs splitting by electrolysis to extract O and H. H can be used again to extract more O from regolith by repeating process.If you have access to water may as well produce LH and LOX for little more energy input.