Pictures: Giant Mars Pits Revealed in Sharp Detail

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?"

Published December 21, 2010

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.")

Published December 21, 2010

Martian Mud Volcanoes

Image courtesy NASA/JPL/University of Arizona

Among other recently released pictures from NASA's Mars Reconnaisance Orbiter are these images of apparent mud volcanoes on in Acidalia Planitia, a large basin in Mars's northern lowlands (seen in a fall 2010 HiRISE picture).

Mud volcanoes—which also exist on Earth—form when wet, pressurized sediment buried at depth erupts onto the surface. (Related photo: "'Medusa' Worms Found in Mud Volcano.")

The Martian mud volcanoes might be prime targets in the search for past life on the red planet, according to NASA. (See Mars pictures.)

"If this mud is produced at depth, it could have brought up organic materials that may show biosignatures of some sort of ancient life on Mars," principal investigator McEwen said.

(Also see "Does Mars Methane Indicate Life Underground?")

Published December 21, 2010

Scar in Martian Lava

Image courtesy NASA/JPL/University of Arizona

A gigantic trough (center) slices through Mars's Tharsis volcanic region in a fall 2010 picture by HiRISE.

Called a graben, the 1.2-mile-wide (2-kilometer-wide) depression formed when a block of the planet's crust dropped down between two faults. In this case, the tectonic movement left nearly vertical walls—each about a kilometer (0.6 mile) deep—on either side. (See another picture of a Mars graben.)

"From the scarcity of craters inside the graben, it's estimated to be less than a billion years old," principal investigator McEwen said. "This one is nicely defined because it cuts a well-preserved lava flow."

Published December 21, 2010