Landsat 5 Imaging Halted To Solve Latest Glitch

WASHINGTON -- Technical difficulties with a piece of equipment on the Landsat 5 satellite could mean the end of operations for the 21-year-old remote sensing spacecraft.

The U.S. Geological Survey confirmed Nov. 28 that Landsat 5 started experiencing problems with its back-up solar array drive Nov. 26. The device's function is to keep the solar panels pointed toward the Sun. When the drive's rotation became sporadic, it prevented the solar panels from generating enough power to charge the satellite's batteries.

"How it could get fixed is going to be the subject of much discussion with our engineers over the next few weeks," Jay Feuquay, coordinator of the land remote sensing program at the U.S. Geological Survey, said in an interview Nov. 28. "We're cautiously optimistic we will be able to resume some sort of operations, but we don't know that for sure, and we don't know how close to full operations we'd be able to get."

It is possible Landsat 5 will still be able to operate for more limited use, but details on how that could happen are still unclear, according to Feuquay.

"We'll have to work around whatever the onboard systems are," he said. "It's really whether or not the smart guys doing our engineering are going to be able to pull one more rabbit out of their hat."

Landsat 5 already is operating on its back-up solar array drive. Its primary array failed in January.

Feuquay said scientists should be able to determine what Landsat 5's future is within the next two weeks or so. In the meantime, imaging operations have been suspended for the satellite.

Landsat 5, which launched in March 1984, originally was designed with a three-year shelf life, but has been operating beyond its expected capability until now. The government's other remote sensing satellite, Landsat 7, has its own problems, as its main sensor malfunctioned in 2003, causing it to deliver degraded data since then.

White House policy officials are still deliberating the next course for the Landsat program; a policy decision last year would have put a Landsat imager on the National Polar-orbiting Operational Environmental Satellite System (NPOESS), but problems with NPOESS have made that alternative less likely.

The White House Office of Science and Technology Policy (OSTP) is weighing whether to launch a free-flying Landsat satellite in the meantime as an alternative. OSTP spokesman Donald Tighe did not return a call for comment Nov. 28. Feuquay said the U.S. Geological Survey still is waiting to hear from the office on their final decision, though he confirmed a free-flyer mission is among the alternatives being weighed.

Industry representatives who rely on Landsat data have been lobbying government officials this month with concerns that the lack of decision on how to go forward with Landsat will result in a data-gap where no remote sensing data is being collected for an extended period of time.

Organizations that have sent letters urging a quick decision include the Management Association for Private Photogrammetric Surveyors, the American Society of Photogrammetry and Remote Sensing, and the National Satellite Land Remote Sensing Data Archive Advisory Committee.