PX282 - M2 - possible environments for life

mars

• it lies in the habitable zone around the sun. where liquid water can exist on the surface of a planet, and the atmospheric pressure is just enough
• imaging and sampling show that surface water was abundant in the past
• enhanced deuterium-hydrogen ratio (D/H) provides evidence of past water lost to evaporation
• there is radar evidence of liquid water lakes below ice caps

venus

• it has no surface water, and has an extreme D/H implying extreme water loss
• possible detection of phosphine PH${}_3$ might be a biomarker
• liquid water droplets (in the form of sulphuric acid) do exist in clouds

icy moons of the giants

• europa, which is resurfaced with liquid water from a tidally-heated subsurface ocean

• it has relatively low water content

• thin ocean and maybe hydrothermal vents providing nutrients

• deeper oceans on ganymede will have ice at the bottom, and probably no hydrothermal vents

• enceladus has water geysers with organic chemistry, and molecular hydrogen

• titan may have exotic life in its methane lakes