In what could turn out to be a landmark discovery
in the history of Mars exploration, NASA's Mars Global Surveyor
spacecraft returns data that suggests there may be current sources
of liquid water at or near the surface of the red planet.
The new images show the smallest features ever
observed from martian orbit -- measuring about the size of a sport-utility
vehicle. NASA scientists compare the features to those left by flash
floods on Earth. The gullies in the images are located on cliffs,
usually in crater or valley walls, and are made up of a deep channel
with a collapsed region at its upper end. At the other end is an
area of accumulated debris that appears to have been transported
down the slope. Relative to the rest of the martian surface, the
gullies appear to be extremely young, meaning they may have formed
in the recent past.