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Ultraviolet Imaging Spectrograph (UVIS) from July 14, 2005
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Enceladus Atmosphere -- Star
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| Description |
Enceladus Atmosphere -- Star Struck |
| Full Description |
During the July 14, 2005, flyby of Saturn's moon Enceladus, Cassini's ultraviolet imaging spectrograph made the first direct detection of an atmosphere, first suggested by Cassini magnetometer measurements. The ultraviolet imaging spectrograph observed the star Gamma Orionis as Enceladus crossed in front of the star. The light of the star dimmed as it was obscured by the atmosphere before being blocked entirely by Enceladus itself. The spectrum of the starlight changed as it passed through the atmosphere, indicating the presence of water vapor. The ultraviolet imaging spectrograph results suggest that the atmosphere of Enceladus is not constant and may be consistent with a greater amount of atmospheric gas near the south polar region. The presence of water vapor is more consistent with warm water ice than with magnetospheric sputtering. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The ultraviolet imaging spectrograph was built at, and the team is based at the University of Colorado, Boulder. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The ultraviolet imaging spectrograph team home page is at http://lasp.colorado.edu/cassini . Credit: NASA/JPL/University of Colorado |
| Date |
July 29, 2005 |
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Enceladus Flyby
| Description |
Here on the Gallery page you can find the very latest images, videos and products from the Cassini-Huygens mission to Saturn, including the spectacular launch, spacecraft assembly and the exciting trip to Saturn. |
| Full Description |
This computer generated animation shows what the instruments on board of the Cassini spacecraft will be doing during the July 14, 2005 Enceladus flyby. The upper right panel shows Enceladus in the fields-of-view (boresights) of the cameras on Cassini. The magenta rectangles are Ultraviolet Imaging Spectrograph (UVIS) slits. The red box is the Wide Angle Camera (WAC). The white box is the Narrow Angle Camera (NAC). The red circle and small red rectangles are the fields of view of the Composite Infrared Spectrometer (CIRS) instrument. The lower right panel displays how Enceladus looks to the "prime" instrument at the current time. The left panel tells the viewer the attitude (orientation) of the Cassini spacecraft throughout the flyby, the color of the "beam" on Enceladus tells the viewer which instrument is prime at any time. However, because all four cameras/spectrometers (NAC, UVIS, VIMS and CIRS) all generally co-aligned, all these instruments will be taking data, no matter which slit is shown in the lower right panel. The movie starts seven and a half hours before closest-approach, with a CIRS scan that will provide temperature and composition maps of Enceladus. The Near Angle Camera will take a high-resolution global image of Enceladus. Jut prior to closest approach, Cassini will then turn to view a star whose path will pass behind Enceladus. This will allow the instruments (particularly the UVIS, shown by the magenta slits in the left panel starting at 19:51:50) to search for evidence of a tenuous atmosphere. Next, the spacecraft turns back to Enceladus (now looking at the night side of the body) and does CIRS mapping of the night side. During this observation, Cassini rolls to keep an attitude that is good for the magnetometer. The flyby concludes with another mosaic and a UVIS crescent observation. |
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Enceladus Atmosphere -- Star
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PIA06431
Saturn
Ultraviolet Imaging Spectrog
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| Title |
Enceladus Atmosphere -- Star Struck |
| Original Caption Released with Image |
During the July 14, 2005, flyby of Saturn's moon Enceladus, Cassini's ultraviolet imaging spectrograph made the first direct detection of an atmosphere, first suggested by Cassini magnetometer measurements. The ultraviolet imaging spectrograph observed the star Gamma Orionis as Enceladus crossed in front of the star. The light of the star dimmed as it was obscured by the atmosphere before being blocked entirely by Enceladus itself. The spectrum of the starlight changed as it passed through the atmosphere, indicating the presence of water vapor. The ultraviolet imaging spectrograph results suggest that the atmosphere of Enceladus is not constant and may be consistent with a greater amount of atmospheric gas near the south polar region. The presence of water vapor is more consistent with warm water ice than with magnetospheric sputtering. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The ultraviolet imaging spectrograph was built at, and the team is based at the University of Colorado, Boulder. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov [ http://saturn.jpl.nasa.gov ]. The ultraviolet imaging spectrograph team home page is at http://lasp.colorado.edu/cassini [ http://lasp.colorado.edu/cassini ]. |
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