Deep Martian Holes

Left: A montage image of the "Seven Sisters"--seven dark openings into cavernous spaces on the slopes of Arsia Mons. Researchers have nicknamed the features Dena, Chloe, Wendy, Annie, Abby, Nikki and Jeanne.


Boy, this is weird! I remember seeing Phil Christiansen (who helped design the instruments) walking the halls at ASU when I was there, in 1988/89. He's been quite fortunate in helping make significant advances in planetary science, and this discovery is a major step forward for his group:

NASA's Mars Odyssey spacecraft has discovered entrances to seven possible caves on the slopes of a Martian volcano. The find is fueling interest in potential underground habitats and sparking searches for caverns elsewhere on the Red Planet.

Very dark, nearly circular features ranging in diameter from about 328 to 820 feet puzzled researchers who found them in images taken by NASA's Mars Odyssey and Mars Global Surveyor orbiters. Using Mars Odyssey's infrared camera to check the daytime and nighttime temperatures of the circles, scientists concluded that they could be windows into underground spaces.