The photos, captured by NASA's Mars Global Surveyor spacecraft, were released by NASA's Jet Propulsion Laboratory and San Diego-based Malin Space Science Systems, which operates the spacecraft's camera. Global Surveyor has been in orbit around Mars since 1997.

"This set of photos shows the diversity of things we've been seeing on Mars during the last several months," said Dr. Michael C. Malin, president of Malin Space Science Systems. "We see everything from sand dunes covered with frost, water ice clouds hanging over volcanoes, and ancient craters being eroded by high winds."

The images are available at http://photojournal.jpl.nasa.gov or http://www.msss.com. The photos were released in conjunction with the International Mars Conference being held this week at the California Institute of Technology.