Quote from: theinternetftw on 03/16/2018 06:31 am{snip}Crew vehicle:* Develop and build a Lunar Excursion Vehicle: the LEV. Cabin the size of the LM. 2 tons.* Have on the LEV a hydrolox stage with enough fuel to do TEI and then EOI back to LEO. All told, 6 km/s.* The above requires a mass ratio of 3.7, resulting in a 8 ton vehicle.* Put all that in a cargo module, to be landed by the previously developed cargo lander.{snip}2 tons is a bit low, I would be happier with 3 tons. The Apollo LEM had weak walls because of the extreme weight saving measures used. Upper end caravans are around 5 tons.
{snip}Crew vehicle:* Develop and build a Lunar Excursion Vehicle: the LEV. Cabin the size of the LM. 2 tons.* Have on the LEV a hydrolox stage with enough fuel to do TEI and then EOI back to LEO. All told, 6 km/s.* The above requires a mass ratio of 3.7, resulting in a 8 ton vehicle.* Put all that in a cargo module, to be landed by the previously developed cargo lander.{snip}
Probably, then again launch failure rates are the following....Falcon 1: 60%Falcon 9: 4%Shuttle: .7%
Quote from: ncb1397 on 03/17/2018 05:57 pmProbably, then again launch failure rates are the following....Falcon 1: 60%Falcon 9: 4%Shuttle: .7%Failure rate (last 20 missions):Shuttle/STS: 5%Falcon 9: 0%So?
Quote from: daveklingler on 03/17/2018 04:23 pmThere's another thread where we've been talking about something like this, the "going back to the Moon really fast" thread.I thought it was kind of funny that Bob Zubrin hadn't ever heard of Xeus and ACES, which he's basically describing. In other words, he's rediscovered what Dave Masten figured out, that Centaur makes a great lander with a few mods and also a great tug.But that's fine. Maybe he'll draw more attention to Xeus and ACES, and ULA (and Dave Masten) will get the funding they want to move forward with it a little sooner.Back in 2009 ULA released this paper:
There's another thread where we've been talking about something like this, the "going back to the Moon really fast" thread.I thought it was kind of funny that Bob Zubrin hadn't ever heard of Xeus and ACES, which he's basically describing. In other words, he's rediscovered what Dave Masten figured out, that Centaur makes a great lander with a few mods and also a great tug.But that's fine. Maybe he'll draw more attention to Xeus and ACES, and ULA (and Dave Masten) will get the funding they want to move forward with it a little sooner.
At the risk of going all 'Sheldon Cooper' on you guys - what is the point of arguing about loss of mission and reliability statistics of Shuttle and rocket launchers when we're talking about a fairly decent Lunar mission architecture??!!
There's a thread on NSF from last year; dealing with a Dragon 2 derivative for lunar landing. It was a bit Apollo-redux, in the sense that the Dragon 'Command Module' was left in lunar orbit and a Dragon lander did the descent and ascent. We imagined a lander built around the Dragon pressure shell - no outer aerodynamic mold line and heatshield - surrounded by propellant tanks and mylar, somewhat like the Apollo LM ascent stage was. The thread dealt with hypergolics for propellants. I imagined a version where lunar oxygen could refuel the oxidizer of the Super Draco engines - burning a combo of LOX and MMO.But even though this is a Zubrin lunar architecture study, I though it was related enough to mention. Maybe for the interim; we could concentrate on suggestions and improvements to 'tweak' Dr Zubrin's ideas? I think taking your TEI/EOI propellant up and down with you would be wasteful. Perhaps the crew lander could leave the cryogenic propulsion stage at either EM-1 or high lunar orbit? Then, the Lander could make direct descent and ascent back to the stage, dock with it and fly back to Earth with EOI then done? This is a concept actually a bit close to a previous Dr Spudis paper I once read.
In answer to Final Frontier above - I said a fairly decent mission architecture. In no way did I intend it to be characterized as optimal. I agree that with Vulcan and New Glenn coming; we could talk about several different mission options available. This is why I think we should discuss the good points and any bad points of Zubrin's ideas. No mission architecture is going to please everyone and be deemed 'perfect'. But they can be improved. I used the world 'tweak' earlier...
No refueling a Falcon 9 second stage would not be easier, Falcon 9 S2 was never intended to be refueled you would basically have to build an entirely new stage no point in doing this when they are already into fabrication and testing of BFS.
XBASE is likely to be split off from the ISS and become a LEO spacestation in its own right. Dream Chaser, CST-100 and Dragon 2 on Falcon 9 can deliver astronauts there from about 2021. A second spacecraft could fly them to the Moon.LOP-G and Bigelow Depot may become spacestations in lunar orbit. The Falcon Heavy could fly a Dragon 2 to the lunar spacestation. A reusable lander can live there. Propellant, cargo and consumables could arrive in separate flights.There may be several years between the BFR getting certified to carry cargo and having the upper stages life support certified. See the time between Dragon 1 and Dragon 2.
There may be several years between the BFR getting certified to carry cargo and having the upper stages life support certified. See the time between Dragon 1 and Dragon 2.
Quote from: A_M_Swallow on 03/18/2018 01:35 amXBASE is likely to be split off from the ISS and become a LEO spacestation in its own right. Dream Chaser, CST-100 and Dragon 2 on Falcon 9 can deliver astronauts there from about 2021. A second spacecraft could fly them to the Moon.LOP-G and Bigelow Depot may become spacestations in lunar orbit. The Falcon Heavy could fly a Dragon 2 to the lunar spacestation. A reusable lander can live there. Propellant, cargo and consumables could arrive in separate flights.There may be several years between the BFR getting certified to carry cargo and having the upper stages life support certified. See the time between Dragon 1 and Dragon 2.BFS would be a better choice for a LEV and/or lander since it is currently being developed. BFS could use Dragon 2's life support.Edit: and it's reusable
It is not a decent architecture. Why is this proposal a thing? Why isn't he proposing COTS/CRS/CCDEV for BEO? Something that would be far easier to sell to Congress (there is already discussion of using commercial launchers for pieces of the Lunar Platform thing)? Elephant in the room is being ignored once again, money being wasted on a giant NASA rocket and spacecraft that could be better served elsewhere. Good luck paying for lunar mission elements while simultaneously funding that nonsense. I am somewhat upset that Dr. Zubrin and others in similar positions don't want to talk about this issue. It is only going to get worse and more pronounced as time goes by and the commercial sector continues to mature. They don't want to talk about it to the point they are proposing whole new mission architectures and totally ignoring it.
* Develop and build a Lunar Excursion Vehicle: the LEV. Cabin the size of the LM. 2 tons.* Have on the LEV a hydrolox stage with enough fuel to do TEI and then EOI back to LEO. All told, 6 km/s.* The above requires a mass ratio of 3.7, resulting in a 8 ton vehicle.* Put all that in a cargo module, to be landed by the previously developed cargo lander.