NASA's Dawn Spacecraft Reveals Mysterious Bright Spots On Planet Ceres 

by Mark Carreau
Sep 10, 2015

New imagery from NASA's Dawn mission spacecraft reveals the ever increasing mystique of the dwarf planet Ceres and its gleaming white spots, as the small instrumented probe continues a spiraling stair step descent toward a final lengthy close-up look at the 600 mile wide asteroid with a rocky surface, ice and perhaps subterranean liquid water and the chemistry required for biological activity.

Past telescopic surveys hint at the latter.

"Soon, the scientific analysis will reveal the geological and chemical nature of this mysterious and mesmerizing extraterrestrial scenery," Marc Rayman, chief engineer and mission director for NASA's Jet Propulsion Laboratory led mission, noted in a Sept. 9 mission update.

One of the impressive images collected by Dawn from its current 910 mile high orbital vantage point features scattered bright white stains in the midst of Ceres' Occator crater, anchored by a concentrated splotch in the middle of the depression. In some places, the crater wall rises vertically for a mile.

In March, Dawn became the first spacecraft to enter orbit around a dwarf planet as it approached Ceres. Launched in 2007, the spacecraft stopped first at the asteroid Vesta for a 2011-12 orbital survey before pressing toward its final destination. The stair step descent strategy has so far offered orbital vantage points of 8,400, 2,730 and currently 915 miles altitude.

In contrast, NASA's New Horizons spacecraft sped within 7,800 miles of Pluto, the much more familiar but vastly more distant dwarf planet on July 14 and will be transmitting its findings back to Earth for yet another year.

In December, Dawn will begin a two month trek to its lowest vantage point, orbiting Ceres from just 230 miles altitude for three months.

The spacecraft is currently working without reaction wheels for aiming. Launched with four of the gyroscopes for fine pointing during the mapping phases and communications with Earth,  Dawn experienced reaction wheel failures in June 2010 and August 2012, placing ever more pressure on the mission team to use the spacecraft's  hydrazine fueled thruster network as an alternative.

Under current planning, the remaining reaction wheel pair will return to duty at the 230 mile high vantage point. Observations could be extended depending on funding and the performance of the reaction wheels and hydrazine fuel reserves. Dawn's mission is currently funded until June.

Nonetheless, there are no plans to descend further in order to prevent Dawn from crashing to the surface for at least a half century and possibly contaminating a solar system destination with life's precursors.

Please log in or register to post comments.

We use cookies to improve your website experience. To learn about our use of cookies and how you can manage your cookie settings, please see our Cookie Policy. By continuing to use the website, you consent to our use of cookies.