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I found this http://www.marsinstitute.info/rd/facult … ml]article on the great "Romance to Reality" site. It has a great quote about In-Situ Propellant Production: it woun't happen with humans until a robot does it first.
I also took note of their fuel choice: propane from earth combined with oxygen from Mars' carbon dioxide. Maybe this combination makes for a lighter and more reliable rocket. I don't like the idea of lugging super-cold hydrogen to Mars from the earth and expecting it to not boil off.
Who needs Michael Griffin when you can have Peter Griffin? Catch "Family Guy" Sunday nights on FOX.
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I found this http://www.marsinstitute.info/rd/facult … ml]article on the great "Romance to Reality" site. It has a great quote about In-Situ Propellant Production: it woun't happen with humans until a robot does it first.
I also took note of their fuel choice: propane from earth combined with oxygen from Mars' carbon dioxide. Maybe this combination makes for a lighter and more reliable rocket. I don't like the idea of lugging super-cold hydrogen to Mars from the earth and expecting it to not boil off.
On a 6 month flight to mars - cryogenic storage of H2 would have about 15% boil off. The point of H2 is that it's so very very light. You get a hell of a lot of moles of H2 in, say, 100kg, compared to just about anything else.
Doug
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15% is a very significant number when engineering a piece of aerospace hardware. It means that the fuel mass must be 15% more than needed, and the tanks have to be 15% bigger to accomodate it. This all adds up to extra weight.
The problem with propane is that we don't have any engines to burn it. My gut feeling is that it would not be too difficult to modify an exiting engine to burn it. After all, Zubrin wanted to modify the RL-10 to burn methane, and the Russians successfully modified their RD-0120 engine (from the Energia core) to burn methane. The open question is thether it would be easier to start off with a kerosene-burning or hydrogen-burning engine when creating the propane engine.
Who needs Michael Griffin when you can have Peter Griffin? Catch "Family Guy" Sunday nights on FOX.
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15% is a very significant number when engineering a piece of aerospace hardware. It means that the fuel mass must be 15% more than needed, and the tanks have to be 15% bigger to accomodate it. This all adds up to extra weight.
Extra weight - but still a HUGE ammount of weight saving over any other solution. The sort of weight saving that makes the difference between a mission being feasable - and a mission not being feasable.
Doug
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