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Robert Zubrin's Mars Gashopper Airplane
Fraser Cain writes "Universe Today has a story about Robert Zubrin's (Mars Society President) Martian Gashopper Aircraft proposal to NASA. It uses solar power to liquefy carbon dioxide and then use it as a propellant to take off, fly hundreds of km above the surface of Mars like an airplane, and then land vertically again."
Is it possible to use this technology here on Earth? We certainly have the carbon dioxide for the fuel. Are higher temperatures or gravitational forces a showstopper?
While the mobility is an interesting concept (being able to move 100+ km at once), how does this change the vehicle's ability to analyze more area? The other crafts "can only examine a few square metres of ground"... at a time. But then it moves and does it again... The only differences I see is that the gashopper does it's analysis of the "few square metres of ground" then hops ~100km away only to analyze a "few square metres of ground." How is this spotty analysis better than continuous examination? Maybe it could be used in conjunction with other crafts of old style. The gashopper gets sent to interesting locations to determine if they should send a more traditional land-based craft? One thing is does have going for it is the ability to refuel itself.
"The object of war is not to die for your country, but to make the other bastard die for his." - Patton
CO2 sublimates, doesn't it? Might not make any difference for their application though.
Its a good idea NOT to have to import hydrocarbons as the nearest filling station is back here, far far away. CO2 is pretty plentiful.
The wings holding the solar panels would have to be self-cleaning though.
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What kind of response times do you get from mars? I mean, could you interactively fly this thing, or would you just kind of point it and it would end up in some random location, in that general direction?
If the latter, what's the advantage over, say, one of those tumbleweed style bots. What about a tumbleweed with "brakes", that can stop, expore, then curl back up into a ball and move along?
Mars exploration sounds like a candidate for the KISS principle to me.
I don't need no instructions to know how to rock!!!!
I remember some dude that had created Mars planes on a simulator, using real NASA-supplied data.
His findings: low gravity and ultrathin atmosphere are bitches.
For one, the ultrathin atmosphere (air density 1% of the Earth's) requires huge wings and a very high speed to generate enough lift.
Taking-off and landing are almost impossible. The planes needs a speed of 400 knots to take off. Landing is very... hard because low gravity prevents you from using brakes, and low air density from using reverse thrust.
Of course, the Gashopper isn't supposed to take off or land (it could not anyway). However, it'd still need massive horsepower and huge wings - all of which make it hard to cram the Mars plane into a space probe.
Bottom line: if the plane has been successfully tested on Earth, it is unlikely to work on Mars.
Disclaimer: I am not a Mars aerospace engineer. But that guy's findings were definitely interesting.
Odd: I get the exact opposite impression from Zubrin's book; he has consistently decried the shuttle program as a huge waste of time and money. He has also described Nasa in short as a goal-less money-eating machine with no worthy purpose; and made rock-solid, scientifically sound proposals (a conclusion I reach by observing that thousands, rather than mere tens or hundreds of other scientists - including other Nasa scientists - agree that they are sound) for unmanned exploration of Mars followed by a humans-to-Mars program, all within my lifetime. I tend to place him in the same category as Burt Rutan, i.e. maverick visionary, rather than 'crank'. Maybe you have your Zubrins confused... try here for better info: http://www.marssociety.org/