Comets carried noble gases to Earth

Measurement of argon on Comet 67P prompts new theory of space projectiles’ role

Comet 67P

ARGON DELIVERY  Comets such as 67P, seen close up in this March 1 image from the Rosetta spacecraft, might have delivered noble gases and prebiotic material to Earth, a new study suggests.

NavCam/Rosetta/ESA (CC BY-SA IGO 3.0)

Asteroids probably ferried water to an infant Earth (SN: 5/16/15, p.