November 18, 2010

Spacecraft Captures Images Of Cometary Snow Storm

Scientists have analyzed images from the EPOXI mission's pictures taken of comet Hartley 2 and found a cometary snow storm created by carbon dioxide jets spewing out tons of ice particles.

Scientists compared the new images to ones taken from a comet the spacecraft had previously visited, Tempel 1. 

"This is the first time we've ever seen individual chunks of ice in the cloud around a comet or jets definitively powered by carbon dioxide gas," Michael A'Hearn, principal investigator for the spacecraft at the University of Maryland, stated in a NASA press release. "We looked for, but didn't see, such ice particles around comet Tempel 1."

The new analysis shows Hartley 2 acts differently than Tempel 1 because carbon dioxide appears to be a key to understanding Hartley 2 and explains why the smooth and rough areas respond differently to solar heating.

"When we first saw all the specks surrounding the nucleus, our mouths dropped," Pete Schultz, EPOXI mission co-investigator at Brown University, said in a press release. "Stereo images reveal there are snowballs in front and behind the nucleus, making it look like a scene in one of those crystal snow globes."

According to NASA, the smooth area of comet Hartley 2 looks and behaves similar to the surface of comet Tempel 1.  However, the rough areas of Hartley 2 are much different.

"The carbon dioxide jets blast out water ice from specific locations in the rough areas resulting in a cloud of ice and snow," Jessica Sunshine, EPOXI deputy principal investigator at the University of Maryland, said in the press release. "Underneath the smooth middle area, water ice turns into water vapor that flows through the porous material, with the result that close to the comet in this area we see a lot of water vapor."

Engineers at NASA's Jet Propulsion Laboratory in Pasadena, California have found that particles weighing slightly less than the mass of a snowflake hit the spacecraft nine times.

"The EPOXI mission spacecraft sailed through Hartley 2's ice flurries in fine working order and continues to take images as planned of this amazing comet," Tim Larson, EPOXI project manager at JPL, stated in the press release.

Scientists will need more studies in order to determine how long this snow storm has been active.

EPOXI stands for the Extrasolar Planet Observatories and Characterization.  Ball Aerospace & Technologies Corp., in Boulder, Colorado, built the spacecraft for NASA.


Image 1: This image from the High-Resolution Instrument on NASA's EPOXI mission spacecraft shows part of the nucleus of comet Hartley 2. Image Credit: NASA/JPL-Caltech/UMD

Image 2: This image shows the nuclei of comets Tempel 1 and Hartley 2. Image credit: NASA/JPL-Caltech/UMD


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