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Rhea's wisps in color CASSINI PHOTO RELEASE Posted: February 23, 2006
To create the false-color view, ultraviolet, green and infrared images were combined into a single black and white picture that isolates and maps regional color differences. Most of the large-scale variations in brightness across the surface are removed by this process. This "color map" was then superimposed over a clear-filter image. The origin of the color differences is not yet understood, but it may be caused by subtle differences in the surface composition or grain sizes making up the icy soil. Wispy markings were seen on the trailing hemispheres of both Rhea and Dione in images taken by NASA's Voyager spacecraft, and were hypothesized by some researchers to be the result of material extruded onto the surface by ice volcanism. Cassini's earlier revelation of the braided fractures on Dione led to speculation that Rhea's wisps might also be created by fractures. This view shows terrain on the trailing hemisphere of Rhea (1,528 kilometers, or 949 miles across). North is up. The image was taken using the Cassini spacecraft narrow-angle camera at a distance of approximately 245,000 kilometers (152,000 miles) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 30 degrees. Image scale is 1 kilometer (4,771 feet) per pixel. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo. |
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The seventh flight of the space shuttle is remembered for breaking the gender barrier for U.S. spaceflight. Sally Ride flew into space and the history books with her historic June 1983 mission, becoming America's first woman astronaut. STS-7 also launched a pair of commercial communications spacecraft, then deployed a small platform fitted with experiments and camera package that captured iconic pictures of Challenger flying above the blue Earth and black void of space. The crew members narrate highlights from the mission in this post-flight film presentation.
The space shuttle program became a two-orbiter fleet on April 4, 1983 when Challenger launched on its maiden voyage from Kennedy Space Center. The STS-6 mission featured the first ever spacewalk from a space shuttle and the deployment of NASA's first Tracking and Data Relay Satellite. The four astronauts narrate a movie of highlights from their five-day mission in this post-flight presentation.
Commander Steve Lindsey and his crew, the astronauts set to fly the second post-Columbia test flight, hold an informal news conference with reporters at Kennedy Space Center on Feb. 17. The crew is in Florida to examine hardware and equipment that will be carried on the STS-121 flight of shuttle Discovery.
NASA Administrator Mike Griffin and his No. 2, Shana Dale, appear before the House Science Committee on Feb. 16 to defend President Bush's proposed 2007 budget for the space agency. Congressmen grill Griffin and Dale about the budget's plans to cut funding for some science programs.