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« Obama objects to bill to ban interrogations by contractors | Main | In Iran, Rafsanjani calls for release of political prisoners »

July 17, 2009


jj mollo

I don't think Bradbury had the necessary engineering background to estimate the necessary size of the mission. He was more of a literary writer, maybe a psychologist, than a science fiction guy. He did have a point though that these missions would be expensive, maybe even somewhat destructive environmentally. The point is that the need for better launch systems is intense.

The main objective is to be able to get lots of mass into orbit cheaply for whatever projects we want to do. Launch from Earth should use a combination system of three technologies. 1) Circular electro-magnetic catapult, 2) air-breathing scram-jet propulsion to reduce the cost of carrying oxygen, and 3) traditional hydrogen-oxygen rocket propulsion. Someday we'll give it all up in exchange for a space elevator, but not for a while yet.

Mars missions, for the sake of balancing speed and mass opportunities, should also use a combination. In addition to traditional thrusters, they should use ion or plasma propulsion(pdf) using nuclear power (submarines have used very compact and reliable reactors for years), along with solar wind sails in order to allow the maximum mass transport percentage-wise. Braking will require reversing the plasma thrusters past midpoint and making use of traditional thrusters along with atmospheric braking. I suspect that sails could also be used for braking somehow if the trajectory were configured carefully, though I'm not sure how. The keel analogy does not apply in space, and I'm not sure how much it would help.

I think that developing and using the right technologies might actually be more important than the mission itself. I sure want it to happen, but not just once.

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