NASA's Voyager craft have ventured where no other human machines have ever gone — the space between the stars. But that comes with a cost.

At some 15 and 12 billion miles away, Voyager 1 and 2 are beyond the protective bubble of the sun, called the heliosphere. Out in this realm of interstellar space, the nearly 50-year-old probes have a higher probability of damage from hostile, high-speed particles, called galactic cosmic rays, owing to a higher number of particles zooming by every...

Continue Reading NASA's Voyager is in hostile territory. It's 'dodging bullets.'