Stardust Craft Tested for Damage After Solar Storm By Lee Siegel Science Writer posted: 07:05 pm ET 08 August 2000 ET
stardust_update_000808
Originally posted 4:45 p.m., 8/8/00
A test performed Tuesday August 8 ruled out fears that solar flares damaged the camera on the Stardust spacecraft, which is due to photograph
Comet Wild 2 and collect collect comet dust in 2004. Now engineers will try to fix another problem that threatens to degrade Stardusts comet pictures.
"The flares didnt do a thing to us," said Ray Newburn, who heads the
Stardust imaging team at NASAs Jet Propulsion Laboratory in Pasadena, Calif.
NASA earlier had feared possible
solar radiation damage to the NAVCAM camera s electronic sensor. The agency had said the July solar flares might increase background "noise" that could "mask" Stardusts images of dim stars and Comet Wild 2.
Engineers tested the camera by turning on the electronic sensor -- known as a CCD or charge couple device -- without opening the shutter. A test image showing a known uniform shade of gray would indicate there was no damage, while brighter gray would indicate there was damage, said Tom Duxbury,
Stardust soars above Cape Canaveral Air Force Station, Florida moments after launch on February 7, 1999.
Stardusts acting project manager. Newburn said the lack of solar radiation damage means engineers now will proceed with a two-week effort to use the cameras heater to burn off contaminants coating the sensor. That repair was delayed while engineers first checked for radiation damage.
Officials confirmed 10 months ago that the camera sensor was coated with contaminants that might degrade the cameras resolution, or sharpness of detail, Duxbury said from Moscow, Russia, where he was vacationing. The material probably vented off the spacecraft after its 1999 launch, he added.
Stardust, launched from Florida, is on a
$199 million mission to photograph Comet Wild 2 (pronounced "vilt two"), collect dust from the comet on January 2, 2004, then return the sample to Earth in January 2006 via a reentry capsule that will parachute onto military land in Utah.
The sun is expected to reach the peak of its 11-year activity cycle late this year. In mid July, powerful solar flares buffeted Earth with the biggest geomagnetic and solar-radiation storms in years. Duxbury said the effects were noted by cameras on NASAs
The same people built the camera on Stardust, which at the time was much closer to the sun than Galileo or Cassini. So the designers recommended testing Stardust rule out solar-radiation damage, Duxbury said.
An artist's rendering of Stardust with its Dust Collector deployed, using Aerogel to capture interstellar grains.
He said engineers earlier had determined the camera sensor was coated with contaminants because navigation images showed stars smeared over many pixels instead of appearing as sharp, bright points.
If not corrected, "we would definitely lose resolution on the camera," and Stardust would be able to detect Wild 2 less than a month before its encounter instead of two months in advance, Duxbury said.
Even so, "our navigators believe they will be able to navigate sufficiently to meet our primary objectives" at Wild 2, he said, noting that burning contaminants off the sensor "is more so we get prettier pictures" of the comet.
Stardust is scheduled to fly within 3,730 miles (6,000 kilometers) of Earth on January 15, 2001, using this planets gravity to help boost it out to the orbit of Wild 2.
Duxbury said that before and after the flyby "we will take a whole set of images to determine the actual performance of camera" and determine how pictures will be impaired if the coating cannot be boiled off.
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