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NASA Wants Astronauts on Mars by 2010
FeloniousPunk writes "According to
this article
in the UK Guardian, NASA intends to send a manned mission to Mars by 2010, using nuclear propulsion. President Bush may announce this project, called Project Prometheus, at the State of the Union address." Here's
good background and context;
for technical background, I recommend
Zubrin
or
Stern.
The JPL will be involved in developing the nuclear propulsion tech, intended to cut the interplanetary trip from six months to two. Apparently the theory is that this proposal won't get shot down like the last Mars proposal because the shorter mission will save money. Here's hoping public response has progressed beyond "oh no! did he say nuclear?!"
In related news,
jkcity writes:
"according to this article by the BBC, the Chinese plan to have a man in space by October 2003."
Fat Chance.
Not that i don't think we should be going there, I just don't think it will happen by then. America lost its interest in Space Travel long ago and they will have no interest in funding this. It's going to take another country doing it first to provoke America to get on the ball. Even then we'll only be doing it out of spite. Of course if this proposal is based on one of Bush's magical projected revenue formulas they won't have enough money to even buy spacesuits by then.
If you wanna get rich, you know that payback is a bitch
Correct, and we are still talking rocket engines. Except that instead of heating and expelling propellant thanks to a chemical reaction (hydrogen + oxygen -> water), you use a nuclear reaction (pump hydrogen--or just about any gas--into a nuclear reactor, heat it like hell).
The difference is that a nuclear rocket is much more efficient: the exhaust speed is much higher. Therefore the propellant mass required for a given change in speed is exponentially lower, due to the "rocket equation":
m/m0=exp(dv/u)
where m0 is your ship's dry mass, m its total mass (including propellant), dv the change in speed you aim for, and u the exhaust speed.
It's not as cut and dried as that.
I worked at the JPL last summer with the MER group (MER: the next Mars rovers). It was a great place to be and the technology they had was impressive. Still, there's only so much a teleoperated robot can do with a 20 minute time lag, slow rad hardened processors, and one (sensor-laden) arm. If I recall correctly, the off-the-cuff figure tossed around there was that a human geologist on site could accomplish in 45 seconds what an earth-based team driving a Mars rover could do in an hour.
It has always been more cost effective to send robots to Mars instead of people. Don't think, though, that you can just send one of these guys up and find out everything you want to know!
--Tom
MAN SHOOTS ROVER!
aren't there easier/faster ways of propulsion already in existance than even nuclear?
Right now, nothing even comes close to uranium/plutonium for energy density. There are really two issues: power and reaction mass. A rocket combines the two, but a nuclear propulsion system doesn't. If ice is the reaction mass, then you can "refuel" on a comet. The more energy per unit of reaction mass you can get, the less of it you need.
There are already ion engines in existance, solar powered, but they are very low powered, incapable of moving significant mass through space at a useful speed.
Right, and it would help to use a fuel which has a low specific heat (that is, it takes little energy to heat it up) and also which doesn't take a lot of energy to go through phase changes. For each phase change a substance goes through it soaks up energy which could be better used in propulsion.
Hydrogen is better than water because hydrogen dissociates into a vapor with very little energy, where water takes a lot of energy to turn into steam. Water also will soak up a lot of energy in heating (high specific heat) up to the temperatures generated in the nuclear reaction, whereas hydrogen does not need as much energy to get up to temperature. In other words, you get more thrust out of equal masses of hydrogen and water with the same energy put into them.
However, there are other factors to consider. The main advantage of water is that it is easy to find, easy to store and pump around, can be used as a moderator for the nuclear reaction, can be used as shielding for the astronauts, the astronauts can use as their drinking supply, and they can use it to produce their oxygen supply. Hydrogen is a total mess to handle, its only real advantage is that it is a bit more energy efficient as a reaction mass. Water is generally accepted as a very good reaction mass due to these factors. The usability of water will most likely far outweigh any benefits you would get from using hydrogen.
Sapere aude!