extremophiles

Tardigrades — eight-legged microscopic animals roughly half a millimeter long — have survived exposure to the vacuum of outer space, temperatures from -272°C to 150°C, pressures six times the deepest ocean trench, and radiation doses 1,000 times the lethal threshold for humans. They accomplish this not by being indestructible, but by entering a state of suspended animation called cryptobiosis that effectively stops time in their cells. The study of these organisms has redrawn the boundary of where life can exist — and raised serious questions about what might be alive elsewhere in the solar system.

Astrobiology covers extremophiles, habitability criteria, biosignatures, candidate worlds (Mars, Europa, Enceladus), the Drake equation, and the Fermi paradox.

A thought experiment on alien biology, first contact protocols, and Fermi paradox resolutions — what discovering extraterrestrial life would really mean.