Images: Orbiter explains bizarre Mars textures

SAN FRANCISCO--NASA's newest Mars orbiter has helped explain some strange textures near the planet's south pole, informally called Ithaca.

The Mars Reconnaissance Orbiter has taken high-resolution images, including multiple views of the same spot and 3D images taken with stereoscopic cameras. The result is a better understanding of surfaces that researchers have variously described as spiders, lace, and lizard skin.

NASA's Jet Propulsion Laboratory and scientists from the University of Arizona-Tuscon revealed the results Tuesday at the American Geophysical Union conference here.

These images show streaked black smudges that scientists already had believed were caused by gas jets that burst through the surface and deposited dust and other substances downwind. NASA now believes the lighter colors are caused by frozen carbon dioxide.

The researchers think the jets contain gaseous carbon dioxide. When it bursts free, it expands and cools, and some is deposited as frost in the smudges. The darker areas are believed to be composed of dust, NASA said.

Why would there be gas jets in the first place? The scientists believe carbon dioxide freezes on hillsides there in the winter and thaws in the summer. The resulting gas travels upward, but underneath the frozen cap, carving channels as it goes.