mercredi 10 juin 2015
Bright Spots Shine in Newest Dawn Ceres Images
NASA - Dawn Mission patch.
June 10, 2015
New images of dwarf planet Ceres, taken by NASA's Dawn spacecraft, show the cratered surface of this mysterious world in sharper detail than ever before. These are among the first snapshots from Dawn's second mapping orbit, which is 2,700 miles (4,400 kilometers) above Ceres.
Image above: The brightest spots on dwarf planet Ceres are seen in this image taken by NASA's Dawn spacecraft on June 6, 2015. Image Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
The region with the brightest spots is in a crater about 55 miles (90 kilometers) across. The spots consist of many individual bright points of differing sizes, with a central cluster. So far, scientists have found no obvious explanation for their observed locations or brightness levels.
"The bright spots in this configuration make Ceres unique from anything we've seen before in the solar system. The science team is working to understand their source. Reflection from ice is the leading candidate in my mind, but the team continues to consider alternate possibilities, such as salt. With closer views from the new orbit and multiple view angles, we soon will be better able to determine the nature of this enigmatic phenomenon," said Chris Russell, principal investigator for the Dawn mission based at the University of California, Los Angeles.
Image above: A large crater in the southern hemisphere of dwarf planet Ceres is seen in this image taken by NASA's Dawn spacecraft on June 6, 2015. Image Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
Numerous other features on Ceres intrigue scientists as they contrast this world with others, including protoplanet Vesta, which Dawn visited for 14 months in 2011 and 2012. Craters abound on both bodies, but Ceres appears to have had more activity on its surface, with evidence of flows, landslides and collapsed structures.
Additionally, new images from Dawn's visible and infrared mapping spectrometer (VIR) show a portion of Ceres' cratered northern hemisphere, taken on May 16, including a true-color view and a temperature image. The temperature image is derived from data in the infrared light range. This instrument is also important in determining the nature of the bright spots.
Image above: Craters in the northern hemisphere of dwarf planet Ceres are seen in this image taken by NASA's Dawn spacecraft on June 6, 2015. Image Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
Having arrived in its current orbit on June 3, Dawn will observe the dwarf planet from 2,700 miles (4,400 kilometers) above its surface until June 28. In orbits of about three days each, the spacecraft will conduct intensive observations of Ceres. It will then move toward its next orbit of altitude 900 miles (1,450 kilometers), arriving in early August.
On March 6, 2015, Dawn made history as the first mission to visit a dwarf planet, and the first to orbit two distinct extraterrestrial targets. At its previous target, Vesta, Dawn took tens of thousands of images and made many observations about the body's composition and other properties.
Images above: Images from Dawn's visible and infrared mapping spectrometer (VIR) show a portion of Ceres' cratered northern hemisphere, taken on May 16, 2015. Images Credits: NASA/JPL-Caltech/UCLA/ASI/INAF.
Dawn's mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit: http://dawn.jpl.nasa.gov/mission
More information about Dawn is available at the following sites: http://dawn.jpl.nasa.gov and http://www.nasa.gov/dawn
Images (mentioned), Text, Credits: NASA/JPL/Elizabeth Landau/Tony Greicius.
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Publié par Orbiter.ch à 15:56