Mars: Foundations

Mars is a cold, dry terrestrial planet with a thin carbon-dioxide atmosphere, giant volcanoes, deep canyons, polar ice caps, widespread impact terrain, and abundant evidence that liquid water was more important in its ancient past.

Mars's lower gravity and lack of active plate tectonics allowed volcanoes to remain over long-lived mantle sources and grow to extreme size.

Orbiters, landers, and rovers have mapped channels, deltas, layered sediments, hydrated minerals, volcanic landforms, and polar deposits.