NASA detects cave 'skylights' on Mars

FLAGSTAFF, Ariz., Sept. 24 (UPI) -- NASA spacecraft have detected entrances to seven possible caves near a Martian volcano, increasing interest in that planet's possible underground habitats.

Very dark, nearly circular features as large as 820 feet in diameter puzzled researchers who found them in images taken by the National Aeronautics and Space Administration's Mars Odyssey and Mars Global Surveyor orbiters. Using infrared imaging, NASA scientists concluded the circular features might be openings to cavernous spaces beneath the planet's service.

"They are cooler than the surrounding surface in the day and warmer at night," said Glen Cushing of Northern Arizona University and a member of the U.S. Geological Survey's Astrogeology Team. "Their thermal behavior is not as steady as large caves on Earth that often maintain a fairly constant temperature, but it is consistent with these being deep holes in the ground."

A report of the discovery of the possible cave skylights by Cushing and his colleagues was published online recently by the journal Geophysical Research Letters.