There are no hospitals in space. The closest A&E is back on Earth, and astronauts can't exactly jump in a cab to get there. So what happens if the sun burps out a massive blast of radiation while an astronaut is space-amblin' by?
We've seen people attempt invisibility cloaks for ages, mostly failing miserably, even in films. But how about hiding something with darkness. That's what researchers using carbon nanotube forests are attempting to do.