India, Oct. 29 -- Imagine sending a tiny lab to deep space, only to learn the experiment never woke up. That's pretty much what happened to NASA's BioSentinel. The cereal box-sized satellite carried living yeast and flew past the Moon, according to NASA's mission overview. The aim was to test the effects of deep-space radiation on living cells. But the yeast did not grow.

Astronauts on the International Space Station orbit about 250 miles above the Earth. Earth's magnetic field protects them from much of the radiation that can damage DNA in our cells and lead to serious health issues. Future crews venturing farther into space might not have that protection. They will be exposed to more dangerous radiation and will need heavy shielding. S...