Quote from: TrevorMonty on 12/12/2018 08:20 am<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.Sure, if that is the method you are using.Melt phase electrolysis is also another possibility - broadly how aluminim is made.
<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.
I listened in on the call during Jason Crusan’s Gateway presentation this week. He spent a lot of time discussing the Gateway Lunar Lander. He was specifically asked about ISRU and he said that a fuel combination has not been selected for the lander at this point and that the trade space is open to various types including methalox, hydrolox and hypergolics. There’s an imminent lander study broad agency announcement where they will fund 6-9 month studies to refine the design including propellant selection. He also mentioned that there is a desire to have all three elements be reusable at some point but it will not be a requirement for the initial descent elements. Hope this helps.
Was anything said about how propellant is actually sent to NRHO to enable this "reusable" architecture? Based on a previous slide, total mass of all ascent & descent stages is 21-27 tonnes ->24 tonnes average. Assuming 0.8 propellant fraction, that's about 20 tonnes of propellant to be refueled per surface mission.SLS Block 2 can deliver 45 tonnes TLI, of which Orion is 25.8 tonnes leaving only 19 tonnes available for propellant, tanks and maneuvering to NHRO. This leaves a very tight to impossible margin for a single SLS + Orion to accomplish a lunar landing, or the descent stage is carried as co-manifested cargo, in which case you still need to deliver 20 tonnes of propellant to Gateway (in excess of supposed limits of commercial vehicles).Best case a lunar mission is one SLS Block 2 + Orion + propellant, plus a new descent stage on a commercial vehicle.Worst case one SLS Block 2 + Orion + Descent vehicle, 2 expendable propellant transfer vehicles sent on commercial vehicles.
Using the Gateway to land astronauts on the Moon allows the first building blocks for fully reusable lunar landers. Initially NASA expects two of the lander elements to be reusable and refueled by cargo ships carrying fuel from Earth to the Gateway. The agency is also working on technologies to make rocket propellants using water ice and regolith from the Moon. Once the ability to harness resources from the Moon for propellant becomes viable, NASA plans to refuel these elements with the Moon’s own resources. This process, known as in-situ resource utilization or ISRU, will make the third element also refuelable and reusable."
NASA intends to release a solicitation under the second Next Space Technologies for Exploration Partnerships (NextSTEP-2) Broad Agency Announcement on January 2, 2019 to seek proposals from industry in support of design analysis, technology maturation, system development and integration, and spaceflight demonstrations for a human lunar landing system. An Industry Forum is planned, tentatively scheduled for January 8, 2019 at NASA Headquarters. Confirmation of these dates and additional details will be posted soon.
{snip}Will be interesting to see if this is an open solution RFP or if NASA seeks to have bidders conform to their predetermine 3 part lander. Simply put does SpaceX get to propose Starship? Does ULA have an opportunity to propose XUES? Lockheed and their lander?
{snip}This NextSTEP-2 Appendix E will include a NASA reference human lander architecture configuration. The full architecture will include a Descent Element, Ascent Element, Transfer Vehicle, Refueling Element, and Surface Suit. NASA plans to launch the first demonstration mission in 2024. The minimum objective of this mission is to demonstrate a lunar surface landing with one or more Descent Elements capable of supporting a future human lander that includes both Descent Element and Ascent Element. Contracts awarded under Appendix E may have multiple phases. The first will be for brief studies to mature requirements, tailor applicable standards, procure long-lead parts and implement technology maturation plans for early risk reduction ...
Quote from: Patchouli on 12/08/2018 06:04 pmWith 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.Yeah, it seems odd that they're talking about refueling and reuse of stages in lunar orbit but act as though you couldn't do the same thing in LEO--even if the rocket isn't a lander with legs on it.~Jon
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.
I don't understand... while SSTO is extremely hard on Earth (9.5 km/s) the Moon seems a little easier (2.5 km/s, one way, 5 km/s, two way). It is a little sad NASA can't build a lunar SSTO. Is maintenance or reliability an issue ? on Earth there are entire OPF for maintenance. Around the Moon, there is none.
Specification of possible reusable tanker vehicle flying full from LEO to low lunar orbit (LLO) and empty back to LEO.Using Wikipedia data.Payload of SLS Block 1 to LEO is 95 tonne.Payload of Falcon Heavy to LEO is 63.8 tonne.Payload of Falcon 9 expendable to LEO is 22.8 tonne.Payload of Atlas V to LEO is 20.5 tonne.Dry mass of tanker including main engine, RCS, its own fuel tanks, structure, avionics, solar panels, sun shield, cooling system, docking system, pump and payload tank is To Be Determined (TBD).Delta-v LEO to LLO using chemical thrusters is 4.04 km/s one-wayDelta-v LEO to LLO using electric propulsion is 8.0 km/s one-wayMasten Broadsword engine producing 35,000 lbf thrust vacuum burning methane/LOX Isp ~321.Masten Machete engine producing 1,000 lbf burning MXP-351 Isp 322 s (probably 4 off engines).VASIMR producing 5 N (1.1 lbf) burning Argon Isp 5,000 s.How much could such a tanker deliver?
Quote from: A_M_Swallow on 12/14/2018 08:51 pmHow much could such a tanker deliver?ULA distributed launch paper had Vulcan Heavy using 2 launches, delivering 20t to GSO, similar DV to Gateway.A Vulcan + NG distributed launch should be good for 23t and probably cheaper. Another advantage of using this combination is launches can be days apart as they launch on separate pads. 2xVulcan would need 2-3wks for 2nd launch.
How much could such a tanker deliver?
I understand why NASA is going this route. A project of this scale on or around the moon requires heavy lift, if not super heavy lift vehicles to really make sense from a payload size sense. The only vehicle that NASA has confidence in actually existing any time soon is SLS. Yes there are commercial companies with plans, but we have to look at it from NASA's perspective: they are still plans, they are out of NASA's control, and they are not guaranteed. There's no way they can budget around that.
Quote from: JonathanD on 12/14/2018 05:35 pmI understand why NASA is going this route. A project of this scale on or around the moon requires heavy lift, if not super heavy lift vehicles to really make sense from a payload size sense. The only vehicle that NASA has confidence in actually existing any time soon is SLS. Yes there are commercial companies with plans, but we have to look at it from NASA's perspective: they are still plans, they are out of NASA's control, and they are not guaranteed. There's no way they can budget around that.Sure they can. Put the companies under contract to provide a certain launch capability by a certain date. NASA has not developed a launch vehicle since the early 1980's and has not developed one that delivered on its specs since the 1960's. ULA and SpaceX are both more credible rocket builders than is NASA.
I have some sympathy for NASA at the moment on this basis.
Put a proven rocket-building company under contract to provide a stated capability by a fixed date. That won't eliminate all of the risk, but it would be much less risky in terms of cost and schedule than relying on NASA to complete SLS.
Quote from: Proponent on 12/17/2018 09:58 amPut a proven rocket-building company under contract to provide a stated capability by a fixed date. That won't eliminate all of the risk, but it would be much less risky in terms of cost and schedule than relying on NASA to complete SLS.Who do you think is building SLS, NASA employees?
Quote from: JonathanD on 12/17/2018 02:09 pmQuote from: Proponent on 12/17/2018 09:58 amPut a proven rocket-building company under contract to provide a stated capability by a fixed date. That won't eliminate all of the risk, but it would be much less risky in terms of cost and schedule than relying on NASA to complete SLS.Who do you think is building SLS, NASA employees?NASA designed SLS, manages its development and intends to buy SLS rockets which it will launch itself. Any other time the US government wants to launch something into space, it buys launch services.
Quote from: Proponent on 12/17/2018 09:44 pmQuote from: JonathanD on 12/17/2018 02:09 pmQuote from: Proponent on 12/17/2018 09:58 amPut a proven rocket-building company under contract to provide a stated capability by a fixed date. That won't eliminate all of the risk, but it would be much less risky in terms of cost and schedule than relying on NASA to complete SLS.Who do you think is building SLS, NASA employees?NASA designed SLS, manages its development and intends to buy SLS rockets which it will launch itself. Any other time the US government wants to launch something into space, it buys launch services.orbit, yes....space, no....