HiRISE Nabs Deimos

By Nancy Atkinson - March 9, 2009 at 12:50 PM UTC | Planetary Science
deimos.jpg

[/caption] Don't panic – its only Deimos. But what an image this is of the smaller moon of Mars! HiRISE captured this enhanced-color image of Deimos on February 21, 2009, showing the moon's smooth surface – with a few impact craters here and there. The one crater near the middle that looks sharp and crisp was created relatively recently. Deimos is composed fragmental rock, or regolith, rich in carbonaceous material, much like C-type asteroids and carbonaceous chondrite meteorites. Deimos is noticeably smoother than Phobos. (

See images of Phobos taken by HiRISE in 2008

). HiRISE took two images of Deimos, about five and a half hours apart – see below.

[caption id="attachment_26707" align="aligncenter" width="580" caption="Two images of Deimos taken 5.5 hours apart. Credit: NASA/JPL/U of Arizona"]

[/caption] These images have a scale of about 20 meters/pixel, so the features 60 meters or larger can be seen. The images were acquired 5 hrs 35 minutes apart, so the sun was to the upper left in the first (left) image and to the right in the second image. Although the viewing geometry is similar in the two images, surface features appear very different due to the changes in illumination.

There are subtle color variations—redder in the smoothest areas and less red near fresh impact craters and over ridges or topographic highs (relative to its center of gravity). The HiRISE scientists say these color variations are probably caused by the exposure of surface materials to the space environment, which leads to darkening and reddening. Brighter and less-red surface materials have seen less exposure to space due to recent impacts or downslope movement of regolith.

Deimos is named after a figure in Greek mythology representing panic or dread. Only two geological features on Deimos have been given names: the craters Swift and Voltaire are named after two writers who speculated on the existence of Martian moons before they were discovered.

More about the operations of taking the images from the HiRISE team.

Source:

HiRISE

Nancy Atkinson

Nancy Atkinson

Nancy Atkinson is a space journalist and author with a passion for telling the stories of people involved in space exploration and astronomy. She is currently retired from daily writing, but worked at Universe Today for 20 years as a writer and editor. She also contributed articles to The Planetary Society, Ad Astra (National Space Society), New Scientist and many other online outlets.

Her 2019 book, "Eight Years to the Moon: The History of the Apollo Missions,” shares the untold stories of engineers and scientists who worked behind the scenes to make the Apollo program so successful, despite the daunting odds against it. Her first book “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” (2016) tells the stories of 37 scientists and engineers that work on several current NASA robotic missions to explore the solar system and beyond.

Nancy is also a NASA/JPL Solar System Ambassador, and through this program, she has the opportunity to share her passion of space and astronomy with children and adults through presentations and programs. Nancy's personal website is nancyatkinson.com