If you're leaving a return stage in LMO, why not leave the ERV hab there also? I don't think there's any way to keep a ACES full of LH2 fueled long enough for a Mars return. Boiloff is going to catch up with it eventually.
Quote from: envy887 on 10/19/2017 02:53 amIf you're leaving a return stage in LMO, why not leave the ERV hab there also? I don't think there's any way to keep a ACES full of LH2 fueled long enough for a Mars return. Boiloff is going to catch up with it eventually.Yah the hab could be left in LMO if it's not being used on Mars such as a separate BFS being used for the surface hab I was mostly thinking about getting everything on one BFR.I'm also not sure if ACES would have enough thrust to weight it depends on the version and what engine is used but hydrogen boil off was one reason I figure the F9 US might be a better choice for an ascent stage.The kerosene probably can sit inside it for the entire mission and lox can come from residual propellants in BFS or the Merlin can be switched to a derated Raptor or a cluster of Chase-10s and all the propellants can come for BFS.If the BFS solar arrays could be removed and deployed on the ground they might be able to power enough ISRU for a small MAV just enough to lift a Dragon into LMO.
I believe that the reailities of (very) large scale fuel manufacture on Mars means that any kind of direct return from Mars will come after earlier missions that don't depend on industrial scale mining. But its still worth contemplating.So have you guys considered a scaled version of Elon's vehicles? Perhaps with the ability to land methane but with indigenous oxygen?
Initially I began a thread in the SpaceX department inquiring about applying the ITS booster toward the original Mars Direct effect vehicles. MATTBLAK quoted: QuoteQuote from: MATTBLAK on 05/01/2017 07:08 amThe traditional Mars Direct by Robert Zubrin and David Baker had Direct vehicles of about 45 tons being sent on Trans-Mars Injection. This is about what the SLS Block II with 'Dark Knights' solid boosters could achieve with an Exploration Upper Stage. If the corestage was redesigned for 5x RS-25E and the EUS had slightly higher thrust engines, this could raise the Direct Vehicle's masses to about 50 tons.We probably need to have a new thread about Mars Direct redesigned for alternate launch vehicles such as New Glenn, Vulcan/ACES and Falcon HeavyWhen Baker and Zubrin conceived Mars Direct back in the 1990s there was only the space shuttle and, at best, the Titan rockets available with no signs of commercial rocketry beyond the ULA monopoly or perpetually-stalled-pie-in-the-sky plans within NASA. 20 years later now, we miraculously have a new world opening up despite the end of the space shuttle. There may quickly be a huge range of options Mars Direct launchers to utilize for a plan created when there essentially were none.The thread rules are the following:1) Assume we wish to land 20+ metric ton vehicles onto the Martian surface with as minimal an architecture as possible - i.e. at least 2 but not more than 4 vehicles and launchers per expedition to Mars2) Debate any launch vehicle from any company so long as it has the ability to throw over 20 metric tons to Mars3) Focus discussion on launch vehicles that are active as of 2010 onward; we are trying to update Mars Direct's options4) Discuss the ITS booster as a launcher but NOT the ITS spaceship as one; the spaceship isn't a launch vehicle by itself applicable to Mars
Quote from: MATTBLAK on 05/01/2017 07:08 amThe traditional Mars Direct by Robert Zubrin and David Baker had Direct vehicles of about 45 tons being sent on Trans-Mars Injection. This is about what the SLS Block II with 'Dark Knights' solid boosters could achieve with an Exploration Upper Stage. If the corestage was redesigned for 5x RS-25E and the EUS had slightly higher thrust engines, this could raise the Direct Vehicle's masses to about 50 tons.We probably need to have a new thread about Mars Direct redesigned for alternate launch vehicles such as New Glenn, Vulcan/ACES and Falcon Heavy
The traditional Mars Direct by Robert Zubrin and David Baker had Direct vehicles of about 45 tons being sent on Trans-Mars Injection. This is about what the SLS Block II with 'Dark Knights' solid boosters could achieve with an Exploration Upper Stage. If the corestage was redesigned for 5x RS-25E and the EUS had slightly higher thrust engines, this could raise the Direct Vehicle's masses to about 50 tons.We probably need to have a new thread about Mars Direct redesigned for alternate launch vehicles such as New Glenn, Vulcan/ACES and Falcon Heavy
One of the things that grates on me about Musk's vision (apart from the absurdity of the whole idea of a colony) is the idea of sending civilians into space for several months of zero g and then subjecting them to 4 to 6 gs on Mars entry. I think we can and should do better than that.
I can't comment on the absurdity of a colony because its off topic. But I can say that 5 tonnes per colonist is hopelessly unrealistic.What I will say that is on topic is that 6gs is a lot of force on a civilian plucked at random. What makes it worse is months of bone loss in zero g.Its not a case of grinning and bearing. Its a case of being stretchered out.
Years ago when I was a lot younger and fitter I pulled 6.5 g in a jet fighter for about 20 seconds. Not being a dedicated pilot, I was wrecked for a good 24 hours afterwards. A barely trained person enduring those g's for 5+ minutes during EDL is going to suffer for days.
What makes it worse is months of bone loss in zero g.Its not a case of grinning and bearing. Its a case of being stretchered out.
To my eye, Elon's first couple of flights to Mars look very much like Mars Direct. Zubrin's ideas did not have a hope to be funded. It is not clear how Elon's Mars ambitions will be fully funded, but he does have both enormous financial and technical clout. It is plausable to think that either private investors, philanthropists, and/or the government will step up and contribute the rest of money to make a Mars effort a reality.
https://en.wikipedia.org/wiki/High-G_trainingThe human body is considerably more able to survive g-forces that are perpendicular to the spine....Early experiments showed that untrained humans were able to tolerate 17 g eyeballs-in (compared to 12 g eyeballs-out) for several minutes without loss of consciousness or apparent long-term harm.
Quote from: MickQ on 11/30/2017 11:40 pmYears ago when I was a lot younger and fitter I pulled 6.5 g in a jet fighter for about 20 seconds. Not being a dedicated pilot, I was wrecked for a good 24 hours afterwards. A barely trained person enduring those g's for 5+ minutes during EDL is going to suffer for days.What actually were the issues. Was it all the blood forced into your legs? Lack of blood to the brain?If someone was flat in a properly supporting bed, wouldn't it be pretty similar to the pressure of being under 6 feet of water?https://en.wikipedia.org/wiki/High-G_trainingVertical quote: This seems to be talking about vertical acceleration, as you would experience in a roller coaster or jet doing a turn:The g thresholds at which these effects occur depend on the training, age and fitness of the individual. An untrained individual not used to the g-straining maneuver can black out between 4 and 6 g, particularly if this is pulled suddenly. Roller coasters typically do not expose the occupants to much more than about 3 gHorizontal quote: This seems to be talking about flat on your back.The human body is considerably more able to survive g-forces that are perpendicular to the spine....Early experiments showed that untrained humans were able to tolerate 17 g eyeballs-in (compared to 12 g eyeballs-out) for several minutes without loss of consciousness or apparent long-term harm.[3]