A bacterium already famous for shrugging off extreme radiation and desiccation has now passed another brutal test: surviving the kind of violent impact that could blast rocks off the surface of Mars.

A fungus pulled from NASA cleanrooms kept surviving tests that were meant to mimic nearly every stage of a trip to Mars. That does not mean Mars is about to be seeded with Earth life. However, the ...

The cleanrooms where NASA assembles its spacecraft are among the most sterile places on Earth. Engineers wear full-body suits, air is filtered to remove nearly all particles, and surfaces are scrubbed ...