Stellary Starry Universe

This view of grains from a sand dune near Christmas Lake, Ore., was taken by a test version of the Mars Hand Lens Imager (MAHLI) camera on Curiosity, NASA’s Mars Science Laboratory, which is slated to launch in fall 2011. The image includes three manufactured spheres; each is a 2-millimeter-diameter (0.08-inch-diameter) ball bearing, placed to provide an independent measure of the image scale. Reflected in each sphere is the glow from the camera’s four white LEDs (light-emitting diodes). This image has a resolution of 15.4 microns per pixel, which is about twice as high as the camera resolution on Mars Rovers Spirit and Opportunity. The view covers an area about 1 inch, or 2.5 centimeters, across. Geologists can examine an image like this for information about the composition of the sand. In this case, the largest white grains are pumice fragments and the dark black and gray grains are fragments of basalt. Nearly transparent, slightly yellow crystals are feldspars. The crystals and pumice were erupted by Mount Mazama in its terminal explosion about 7,700 years ago; the volcano is known today as Crater Lake. Image Credit: NASA/JPL-Caltech/Malin Space Science Systems

NASA will hold a news conference at 2 p.m. EST on Thursday, Dec. 2, to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life.

The dark rippled dunes of Mars’ Proctor Crater likely formed more recently than the lighter rock forms they appear to cover, and are thought to slowly shift in response to pervasive winds. The dunes arise from a complex relationship between the sandy surface and high winds on Mars. Similar dunes were first seen in Proctor Crater by Mariner 9 more than 35 years ago. This image was taken by HiRISE camera on board the Mars Reconnaissance Orbiter, currently in orbit around Mars. Image Credit: NASA/JPL-Caltech/University of Arizona

The Soyuz TMA-19 spacecraft with Expedition 25 Commander Doug Wheelock and Flight Engineers Shannon Walker and Fyodor Yurchikhin touches down near the town of Arkalyk, Kazakhstan on Friday, Nov. 26, 2010. Russian Cosmonaut Yurchikhin and NASA Astronauts Wheelock and Walker, are returning from six months onboard the International Space Station where they served as members of the Expedition 24 and 25 crews. Photo Credit: NASA/Bill Ingalls

Harrat Khaybar, Saudi Arabia lies in the western half of the Arabian peninsula and contains not only large expanses of sand and gravel, but also extensive lava fields known as haraat (harrat for a named field). According to scientists, the volcanic field was formed by eruptions along a long north-south linear vent system over the past 5 million years; the most recent recorded eruption took place between 600-700 A.D. The presence of tuff cones — formed by eruption of lava in the presence of water together with other volcanic features indicative of water — in the Harrat Khaybar suggest that the local climate was much wetter during some periods of volcanic activity. Today, however, the regional climate is hyperarid — little to no yearly precipitation — leading to an almost total lack of vegetation. The image was taken by the Expedition 16 crew aboard the Inernational Space Station in March 2008. Image Credit: NASA