NASA’s Phoenix mission discovered water ice just beneath the surface near Mars’s north pole.
Phoenix landed in the northern plains on May 25, 2008. Its robotic arm dug trenches in the soil, exposing bright material that gradually disappeared. Scientists identified the material as water ice because it sublimated after being uncovered and because Phoenix’s instruments chemically analyzed samples.
The lander also studied Martian soil, weather, and the local water cycle. Its wet chemistry laboratory found that the soil was alkaline and contained perchlorate compounds.
Phoenix was a stationary lander rather than a rover. It operated until November 2008, when declining sunlight and seasonal cold prevented its solar panels from producing enough power. Later missions have also confirmed widespread subsurface water ice in Mars’s polar and mid-latitude regions.