North and South Poles; north cap is water ice year-round, south cap CO2 ice over water ice
Estimated Quantity
~3.7 million km³ equivalent water
Enough water to cover Mars to a depth of ~35 meters if melted
As of 2021-01-01
Mars's polar caps contain substantial water ice. The north polar cap is nearly pure water ice (600 m deep, 1,000 km wide) covered in seasonal CO2 frost. SHARAD radar on MRO has mapped the layers in detail. MOLA topography confirms the south cap is offset from geographic south pole and buried under CO2. These are the largest confirmed water repositories on Mars.
Electrolysis to produce rocket propellant (H₂+O₂), life support water and oxygen for crewed missions, radiation shielding via water walls
Reality Check
Polar ice is far from equatorial landing sites — nearest useful water ice deposits are mid-latitude subsurface glaciers
Confidence: high · Last verified 2026-06-01
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