MEDIA RELATIONS OFFICE<br />JET PROPULSION LABORATORY<br />CALIFORNIA INSTITUTE OF TECHNOLOGY<br />NATIONAL AERONAUTICS AND SPACE ADMINISTRATION<br />PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011<br />
http://www.jpl.nasa.gov<br /><br /> CASSINI MISSION STATUS<br /> July 23, 2002<br /><br /> Now within two years of reaching Saturn, NASA's Cassini spacecraft took <br />test images of a star last week that reveal successful results from an extended <br />warming treatment to remove haze that collected on a camera lens last year.<br /><br /> The quality of the new images is virtually the same as star images taken <br />before the haze appeared. In the most recent treatment, the camera had been warmed <br />to 4 degrees Celsius (39 degrees Fahrenheit) for four weeks ending July 9. Four <br />previous treatments at that temperature for varying lengths of time had already <br />removed most of the haze. The camera usually operates at minus 90 C (minus 130 <br />F), one of the temperatures at which test images were taken on July 9 of the star <br />Spica. <br /><br /> "We're happy with what we're seeing now," said Robert Mitchell, Cassini <br />program manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The team <br />will decide in coming weeks whether to proceed with another warming treatment <br />later this year.<br /><br /> Cassini's narrow-angle camera worked flawlessly for several months before <br />and after a December 2000 flyby of Jupiter. Haze appeared when the camera cooled <br />back to its usual operating temperature after a routine-maintenance heating to 30 C <br />(86F) in mid-2001. Lens hazing from engine exhaust or other sources is always a <br />possibility on interplanetary spacecraft. Planners designed heaters for Cassini's <br />cameras to cope with just such a situation.<br /><br /> Before treatment, the haze diffused about 70 percent of light coming from a <br />star, by one method of quantifying the problem. Now, the comparable diffusion is <br />about 5 percent, Cassini engineers Charles Avis and Vance Haemmerle report. <br />That's within one percent of what was seen in images from before the hazing <br />occurred, possibly within the range of statistical noise in the analysis. Comparison <br />images are posted at
http://www.jpl.nasa.gov/images/cassinicamera_caption.html.<br /><br /> Additional information about Cassini-Huygens is online at <br />
http://saturn.jpl.nasa.gov .<br /><br /> Cassini will begin orbiting Saturn on July 1, 2004, and release its <br />piggybacked Huygens probe about six months later for descent through the thick <br />atmosphere of the moon Titan. Cassini-Huygens is a cooperative mission of NASA, <br />the European Space Agency and the Italian Space Agency. JPL, a division of the <br />California Institute of Technology in Pasadena, manages the mission for NASA's <br />Office of Space Science, Washington, D.C. <br /><br /># # # # #<br />GW- 7/22/02 2002-149
