National Geographic : 2004 Jan
WHITE PLANET Snow and ice grip the landscape around Holden crater, at top, in Mars's southern hemisphere in this blend of art and reality. Artist Kees Veenenbos draped wintry white over topographic data from the laser altimeter on the Mars Global Surveyor (MGS) orbiter to simulate how the planet might have looked 50,000 to 500,000 years ago. "Ifyou'd viewed Mars then, you would have called it the white planet," says Phil Chris tensen. Scientists have begun to find dusty snowpacks and other evidence of an icier past far from epo which could help pin point wh liquid water-even life-might exist today. Aram Chaos crater (overleaf) once was underlain with water ice and deper down, liquid water. S violent ption water 5 the ground col ps complex shapes.