Glen Cushing, U.S. Geological Survey (Flagstaff, Arizona) and fellow astrogeologists (scientists who study the geology of celestial bodies) used imaging data from the NASA Mars Odyssey spacecraft to find seven entrances to caves on Mars. They were able to differentiate these caves, which are dark circular features, from craters, which are lighter in color.
The dark circular features, which are called the skylights of the caves, were found to be from 100 to 250 meters (328 to 820 feet) in diameter. They are located on the sides of a volcano called Arsia Mons, which is the southernmost of three volcanos (together called Tharsis Montes) on the Tharsis bulge near the equator of Mars.
Cushing suggests that the caves have an interior opening because the circular structures maintain constant temperatures while the nearby surface temperatures are different.
NASA’s Mars Odyssey is a spacecraft that was launched on April 7, 2001, from Cape Canaveral, Florida. It arrived at Mars on October 24, 2001. While orbiting Mars, its mission is to look for evidence of past or current water and volcanic activity.
Cushing and his fellow researchers presented their findings at the 38th annual Lunar and Planetary Science Conference, which was held in League City, Texas, outside of Houston, from March 12-16, 2007.
The next mission for the Cushing team is to search the rest of the planet Mars for more caves. They are especially interested in lower altitude/higher atmospheric pressure areas that have a better chance of containing liquid water.
Information about the 38th annual Lunar and Planetary Science Conference is found at: http://www.lpi.usra.edu/meetings/lpsc2007/.
The home Web page of the NASA Jet Propulsion Laboratory is: http://mars.jpl.nasa.gov/odyssey/.