Slashdot points to a news item from the University of Washington on a new propulsion idea for space travel. The idea is to use special satellites that would shoot a plasma beam at a spacecraft which would push it to the destination. Another satellite would then be at the destination to shoot a plasma beam in the opposite direction when it came time to slow it down. It is a cool idea, and I recommend reading about it if you're interested in space flight and all things techy. However, I don't think we'll ever use it for manned space flight as the article hopes.

Come on Nick. The idea is pure genius. You remove all that weight for a propulsion system from the space craft and put it on a satellite which can be used by many spacecraft. You can whip over to Mars and back in 90 days. Imagine how much less exposure astronauts would have to radiation. Less time in space means there is less time for something to go wrong. And there is the catch. What if something goes wrong?

As an engineer, I can tell you that the majority of time and effort you spend on projects that involve human health and safety aren't on the things that will go right. You spend the majority of time handling things that will go wrong. You try to account for as many of those worse case scenarios as possible. More importantly, you realize that it's impossible to account for all of them, so you make the effort to make your design as flexible as possible. And for that reason, I don't think any space flight system will ever be used for human space travel if the propulsion system doesn't go with the craft. I think this sort of system would rock for sending stuff into space... Satellites, un-manned explorers, whatever. But people? Nope.

Any spacecraft, even with this system is going to have to contain some sort of propulsion system, even if very small. You need to be able to get into orbit once you get there, wherever there is. And I don't think one of these mag-beam satellites will be able to do that. But will the orbital entry engine be enough to make a course correction in mid space? What if something major goes wrong and you need to be able to do a 180? Without your major propulsion system on board, you've just limited your options significantly. A mag-bean setup seems to much like a one shot deal. If you miss, you're screwed. Somehow I don't think that will ever fly when it comes down to putting people on it. You need your propulsion system on board if for no other reason than to keep your options open... for all the things that might go wrong.