

Spacecraft Traveling Close to Light Speed Should Be Visible with Current Tech - betolink
http://www.technologyreview.com/view/536091/spacecraft-traveling-close-to-light-speed-should-be-visible-with-current-technology-say/

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api
Side point, but I have heard shielding proposals for dealing with the matter
collision problem.

Basically you could create a plasma cloud ahead of yourself and hold it there
magnetically. It would take a ton of energy to generate and maintain, but if
you're doing this at all then you're already pretty good at generating a whole
lot of energy.

Anything impacting your plasma shield would itself become plasma. Plasma can
be controlled by a magnetic field, so as soon as this happens your magnetic
field grabs it and it becomes part of your shield mass.

Many potential relativistic propulsion systems such as fusion or antimatter
rockets have exhaust that is partly plasma, so maybe a simple way to engineer
such a shield would be to just waste a little bit of your propulsion output by
facing it forward combined with a massive electromagnetic field generator.

Seems like generating the energy required to accelerate to these velocities is
like 90% of the problem. But it's possible. There are already paper designs
like Project Orion (thermonuclear pulse rocket) that could achieve as much as
10-20% the speed of light, which is sufficient for close interstellar flights
in a human lifetime.

