Space sensor coaxed to life following bleak troubles
BY JUSTIN RAY
Posted: June 15, 2010
Calling it a miracle recovery after early troubles left engineers wondering if the instrument could ever be activated, scientists have unveiled the first picture from the Solar X-ray Imager aboard the nation's newest weather satellite.
Controllers maneuvered the craft 22,300 miles above the equator and successfully brought online the visible and infrared weather instruments to track clouds, storms and conditions across the Americas.
But efforts to power up the Sun imager were thwarted by an apparent electrical short that prevented the instrument's camera from getting enough voltage to take pictures.
"Since the early checkout of GOES 15 and the anomalous turn-on of the Solar X-Ray Imager, the team has been aggressively pursuing all avenues to recover the instrument," said Andre Dress, GOES N-P deputy project manager at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
"Frankly, we were down to our last straw when all the teams' hard work and efforts finally paid off. We now believe we have a full recovery of the instrument's functionality! It's an incredible story and a true testament of our NASA/contractor teams' expertise, hard work and determination."
The satellite was built by Boeing and the SXI was supplied by Lockheed Martin. The craft, constructed under the name of GOES P, was the third in a series of three next-generation weather satellites deployed for forecasters.
NASA says extensive troubleshooting eventually cleared the electrical fault, boosting the SXI voltages to the expected range and the instrument finally activating on June 3. The image above was taken June 4.
"This is an enormously satisfying outcome," George Koerner, SXI program manager at the Lockheed Martin's Advanced Technology Center in Palo Alto, California.
The exact culprit in the system remains a mystery, but it's thought to be just a random part failure.
"From the data we had, we knew there was a short somewhere within or between the Power Electronics Box and the Camera Electronic Box. We started looking at all the possible areas where the failure could occur and result in this signature," Dress explained in an email.
The list of possible suspects numbered 12 different parts aboard the satellite, and engineers determined some of the components -- only noise filters and not critical to operating the SXI -- could be sacrificed to clear the short.
"We knew that with some of these parts, in the presence of a short, the temperature would rise and possibly fry the part and clear the short," Dress said.
With no other options left, controllers sent commands to begin lengthy power-on tests to get the equipment warm enough to possibly break through the problem. And it worked.
"The hope was that the part temperatures would get high enough to damage the failed part and clear the short. Approximately 16 hours into the testing, the short cleared and the instrument regained all its functionality," Dress said.
Further testing is planned to verify the instrument is properly processing image data.
"We still have a lot of testing to complete, but it looks like the instrument will now operate as expected for the remainder of the mission life," Dress added.
The information obtained from the orbiting SXI instruments help scientists study solar storms that erupt from the Sun, travel through interplanetary space and impact Earth. The disturbances can upset satellites, trigger power grid blackouts and interfere with communications and navigation signals.
"I don't think most people realize how important these space weather instruments are in our everyday life," Dress said. "This data is used by the U.S. Department of Defense, NOAA, NASA and the Federal Aviation Administration in protecting our space assets, land-based assets and directing flight paths for the FAA."
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