Images from the European Space Agency's Mars Express orbiter show changes in the planet's north pole as the martian summer begins, astronomers say. As the planet's summer solstice approached, all the carbon dioxide ice that covers the area in winter and spring had gone, leaving just a bright cap of water ice, an ESA release said Friday.
Water ice, which showed up as bright white areas in the newly released images, occasionally emits large bursts of water vapor into the atmosphere, scientists said.
These processes bear witness to a dynamic water cycle on Mars, they said.
The images were captured by the orbiter's High-Resolution Stereo Camera on May 17, 2010, during the summer solstice, the longest day and the beginning of the summer for the planet's northern hemisphere in the martian year, which lasts about 1.88 Earth years.
