Spacecraft Traveling Close to Light Speed Should Be Visible with Current Technology, Say Engineers

Relativistic spacecraft must interact with the cosmic microwave background in a way that produces a unique light signature. And that means we should be able to spot any nearby, according to a new analysis.
Interstellar travel may be the stuff of science fiction, but it’s straightforward to calculate that it should be possible given the ability to travel at a significant fraction of the speed of light. These kinds of speeds may even be achievable with near future technologies and the tax dollars to make them work.
There are significant challenges, of course. And today, Ulvi Yurtsever and Steven Wilkinson at the defense contractor Raytheon in El Segundo, California, outline another that seems to have been overlooked until now.
These guys point out that any object traveling at relativistic speeds will interact with photons in the cosmic microwave background. This interaction should create a drag that imposes specific limits on how fast spacecraft can travel, they say.
But it should also produce a unique signature of relativistic spaceflight that ought to be visible with today’s technology should any vehicles of this type be zipping through our galactic neighborhood.