Mars Caves?
Image courtesy NASA/JPL/University of Arizona
Looking like space slug hidey-holes, huge pits gouge a bright, dusty plain near the Martianvolcano Ascraeus Mons in a picture taken between October 1 and November 1 by NASA’s Mars Reconnaissance Orbiter (MRO).
Released in December, the image is among a series of new views snapped by MRO’s HiRISE camera that show intriguing geological features on Mars. Each image covers a strip of Martian ground 3.7 miles (6 kilometers) wide and can reveal a detail about as small as a desk—and so far no sign of Star Wars monsters.
MRO’s sister orbiter, Mars Odyssey, first noticed the two deep pits—which are about 590 feet (180 meters) and 1,017 feet (310 meters), respectively—a year earlier using its infrared camera, THEMIS. (Related: “Seven Great Mars Pictures From Record-Breaking Probe.”)
“When compared to the surrounding surface, the dark interiors of the holes gave off heat at night but were cool by day,” said Alfred McEwen, principal investigator on the HiRISE camera.
“So we then decided to target these with MRO because this thermal information may be evidence for these being caves—but the jury is still out on that.”
(See “Mars Has Cave Networks, New Photos Suggest.”)
The MRO has been studying Mars since 2006, beaming back more data than all other past and current missions to the planet combined.
Down the Martian Hole
Image courtesy NASA/JPL/University of Arizona
A sharp close-up of the the larger Martian pit revealed sediment and boulders (seen in a picture taken in fall 2010 by the Mars Reconnaissance Orbiter’s HiRISE camera), as well as hints of sand that was blown inside and trapped in the deepest and darkest parts of the hole, according to NASA.
The holes are believed to be vertical shafts that cut through lava flows along the edges of the Ascraeus volcano. Similar features called pit craters—the result of the ground collapsing above a void—can be found on Hawaii‘s volcanoes. (See “Mars Volcanoes May Re-Erupt, Hawaii Comparison Shows.”)
Scientists are still debating if these are genuine pits, which are simply vertical shafts in the ground, or caves—holes that lead into hidden horizontal undergound passageways.
“The big question is if these are in fact caves,” principal investigator McEwen said. “And do they provide some sort of micro-environment that could have supported life on Mars in the past?”
Youthful Pit on Mars
Image courtesy NASA/JPL/University of Arizona
Car-size boulders punctuate the bottom of the smaller Martian pit (pictured in a fall 2010 HiRISE image). A bright sand dune laced with windblown ripples covers the sloping western side of the hole.
The two pits are believed to be relatively young, according to NASA. As the pits age, the slopes become shallow and widen as they material at the edges collapses inward.
“There are probably thousands of the older ones, and the younger ones like these, which are very steep and dark, may number be up to dozens,” principal investigator McEwen said.
(Related: “Mars Has Liquid Water Close to Surface, Study Hints.”)
Source: nationalgeographic
