Scott Kelly’s physiology, gene activity, and mental performance changed after time aboard the International Space Station, but mostly returned to normal once back on Earth.

An analysis of the scars left by long-gone flows reveals that Mars’s rivers may have run even when scientists thought the planet was drying out.

Rockets can transport humankind to Mars, but only the scientific and medical community can ensure our survival.

By simulating the structure and composition of Mars’s rocky materials, scientists observe how the metal-eating, extreme environment–inhabiting microbe Metallosphaera sedula could alter extraterrestrial environments.