I was reading that chemical rockets won’t take us to Mars (humans at least)-the Hohmann orbits take too long, and radiation exposure would be to dangerous. If we had high-impluse nuclear rockets, we could get to Mars in a few weeks…are these things feasible (with current engineering)? Suppose we are able do design one-how long would it take to build and test?
I like the idea of a 3 week trip to Mars-it makes things a lot easier.
Well, I don’t know what you were reading, but NASA is looking at least semi-seriously at sending a manned mission to Mars within thirty years or so, and they’d almost certainly be using chemical rockets to do it. Yah, it would be a lengthy trip, but that’s part of the point of the International Space Station - to anticipate the problems that arise from long-term human habitation in space. It isn’t a perfect model - I believe the ISS enjoys some protection from Earth’s magnetosphere, which a Mars ship would not. But the radiation levels wouldn’t be constantly high, and I believe the idea would be to have a lead-lined “storm shelter” on the ship for peak radiation times.
This isn’t to say that I think sending people to Mars is a particularly good idea, mind you - it seems like a ferociously expensive boondoggle, and the scientific goals could be achieved far more cheaply and safely with unmanned probes. And the idea that we might someday want to colonize Mars is absurd - Antarctica is infinitely more hospitable to human life than Mars could ever be, and yet no one other than scientists and their support staff wishes to live there.
As for how fast we could develop nuclear rockets - well, depends on what you mean. Some magically exotic device that used a self-sustaining, controlled fusion reaction to heat and expel reaction mass is far beyond anything we could build - we don’t even know how to build fusion reactors on the ground that consistently generate enough energy to be worthwhile. However, there is a quick-and-dirty approach to nuclear propulsion - the nuclear pulse drive, also known as Orion. Link: Project Orion (nuclear propulsion) - Wikipedia
Basic idea is that you build your spaceship on top of a very big metal plate, mounted upon very good shock absorbers. Then you set off nukes under it. Assuming that you’ve built your ship properly (that is, with an insane degree of toughness), it doesn’t go boom - instead, it goes zoom, very fast. That’s high-impulse nuclear propulsion right there, and it could probably have been done with 1960s technology - that’s when it was first proposed. Two problems:
1.) If you’re launching from the surface of the Earth, you’re setting off ground and atmospheric bursts every time you launch a ship. People frown on that, particularly the signatories of the Nuclear Test Ban Treaty.
2.) Once your ship is in space, you now have a whole lot of nukes in space. This, too, is highly illegal, for the very good reason that nukes in space can very rapidly become nukes leaving space, and this makes great powers Very Nervous. Nervous nuclear powers = bad.
The rocket being discussed to go to mars is the VASIMR. It is a plasma rocket that can be powered by solar energy (though a nuclear plant would be more suitable for a mission to Mars) and would cut transit time down to an estimated 39 days. They’re supposed to test the engine on the ISS pretty soon and the prototype recently got a special superconducting magnet it needs for full scale testing here on earth.
Not even high impulse. A crummy 1/10th G – constantly applied – would get us there in thirty days, give or take.
Found this by looking for threads on nuclear rockets. It looks like Russia is trying to build one. Trying.
The 2009 question was never answered about whether a nuclear rocket engine could be developed and if so how long would it take to build and test.
Nuclear thermal rocket engines have already been developed and extensively tested. This was in the 1960s under the NERVA program. The program was successful and full-scale rockets were test fired up to 1 hr at the same thrust needed for a Mars mission.
The NERVA test program met NASA’s specifications, including those related to thrust, thrust-to-weight ratio, specific impulse, engine restart, and engine lifetime.
By the late 1960s the NERVA program had sufficient experience and components to build a space-rated full-scale prototype for flight testing. This never happened.
“NUCLEAR ROCKETS: To Mars and Beyond”: Service Unavailable
Ninjaed by joema…
As mentioned, the Americans developed and tested (but did not fly) successful designs for nuclear rocket motors in the NERVA program. Quite a bit of info in that Wiki article, too.