A growing bounty of images from NASA's Mars Reconnaissance Orbiter reveals that the timing of new activity in one type of the enigmatic gullies on Mars implicates carbon-dioxide frost, rather than water, as the agent causing fresh flows of sand.
NASA's Mars Reconnaissance Orbiter put itself into a precautionary standby mode after experiencing a spontaneous computer reboot on Sept. 15. The mission's ground team has begun restoring the spacecraft to full operations.
Almost 40 years ago, NASA's Mariner 9 spacecraft relayed to Earth the first video images of Mars' northern polar ice cap, revealing a strange pattern of spiral swirls that has puzzled scientists ever since. Using new data from the Mars Reconnaissance Orbiter (MRO), researchers have finally uncovered the secrets of the troughs that snake through the ice cap like a spiraled maze.
New studies of ripples and dunes shaped by the winds on Mars testify to variability on that planet, identifying at least one place where ripples are actively migrating and another where the ripples have been stationary for 100,000 years or more.
Near the center of a Martian crater about the size of Connecticut, hundreds of exposed rock layers form a mound as tall as the Rockies and reveal a record of major environmental changes on Mars billions of years ago.
Dunes of sand-sized materials have been trapped on the floors of many Martian craters. This view shows dunes inside a crater in Noachis Terra, west of the giant Hellas impact basin in Mars' southern hemisphere.