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NASA Spacecraft Sees Cosmic Snow Storm During Comet Encounter

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"The carbon dioxide jets blast out water ice from specific locations in the rough areas resulting in a cloud of ice and snow," said Jessica Sunshine, EPOXI deputy principal investigator at the University of Maryland. "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."

  Part of nucleus of Comet Hartley 2   Particles swirling around nucleus of comet Hartley 2   Active end of nuclues of comet Hartley 2  
  This image from the High-Resolution Instrument on NASA’s EPOXI mission spacecraft shows part of the nucleus of comet Hartley 2.
  This image from the High-Resolution Instrument on NASA’s EPOXI mission spacecraft shows particles swirling in a “snow storm” around the nucleus of comet Hartley 2.
  This 3-D image shows the entire nucleus of Hartley 2 with jets and an icy particle cloud. Image credit: NASA/JPL-Caltech/UMD  

Engineers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., have been looking for signs ice particles peppered the spacecraft. So far they found nine times when particles, estimated to weigh slightly less than the mass of a snowflake, might have hit the spacecraft but did not damage it.

"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," said Tim Larson, EPOXI project manager at JPL.

Scientists will need more detailed analysis to determine how long this snow storm has been active, and whether the differences in activity between the middle and ends of the comet are the result of how it formed some 4.5 billion years ago or are because of more recent evolutionary effects.

EPOXI is a combination of the names for the mission's two components: the Extrasolar Planet Observations and Characterization (EPOCh), and the flyby of comet Hartley 2, called the Deep Impact Extended Investigation (DIXI).

JPL manages the EPOXI mission for the Science Mission Directorate at NASA Headquarters in Washington. The spacecraft was built for NASA by Ball Aerospace & Technologies Corp., in Boulder, Colo.

For more information about EPOXI, visit: http://www.nasa.gov/epoxi

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