NASA - Mars Reconnaissance Orbiter (MRO) logo.
October 20, 2014
These images were taken of comet C/2013 A1 Siding Spring by NASA's Mars Reconnaissance Orbiter on Oct. 19, 2014, during the comet's close flyby of Mars and the spacecraft. Comet Siding Spring is on its first trip this close to the sun from the Oort Cloud at the outer fringe of the solar system. Image Credit: NASA/JPL-Caltech/University of Arizona.
The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter captured views of comet C/2013 A1 Siding Spring while that visitor sped past Mars on Sunday (Oct. 19), yielding information about its nucleus.
The images are the highest-resolution views ever acquired of a comet coming from the Oort Cloud at the fringes of the solar system. Other spacecraft have approached and studied comets with shorter orbits. This comet's flyby of Mars provided spacecraft at the Red Planet an opportunity to investigate from close range.
This composite image shows two versions of each of two of the best HiRISE images of the comet. Shown at top are images with the full dynamic range, showing the nucleus and bright coma near the nucleus. Shown at bottom are versions where the fainter outer coma is brightened, saturating the inner region. The images at left and right were taken about nine minutes apart.
NASA's Mars Reconnaissance Orbiter spacecraft. Image Credits: NASA/JPL-Caltech
Images of comet Siding Spring from HiRISE are online at:
http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18618
The highest-resolution of images of the comet's nucleus, taken from a distance of about 86,000 miles (138,000 kilometers), have a scale of about 150 yards (138 meters) per pixel. Telescopic observers had modeled the size of the nucleus as about half a mile, or one kilometer wide. However, the best HiRISE images show only two to three pixels across the brightest feature, probably the nucleus, suggesting a size smaller than half that estimate.
For more about HiRISE, visit: http://hirise.lpl.arizona.edu
For more about Mars Reconnaissance Orbiter, visit: http://mars.nasa.gov/mro/
For more about comet Siding Spring, including other images of the comet, visit: http://mars.jpl.nasa.gov/comets/sidingspring/
Images (mentioned), Text, Credits: NASA / JPL / Guy Webster.
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