Planetary science. Liquid water found on Mars, but it's still a hard road for life.
Kerr
Richard A
RA
D018559:Exobiology; D005118:Extraterrestrial Environment; D019369:Life; D018535:Mars; D010472:Perchlorates; D018531:Spacecraft; D013696:Temperature; D014867:Water
D010472:Perchlorates; D014867:Water