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Teams study solar array snag on Air Force weather satellite

Posted: April 6, 2014

Engineers are studying a problem that caused the power-generating solar array on a newly-launched U.S. military weather satellite to only partially deploy, but officials said Friday the anomaly has so far not affected operations of the polar-orbiting spacecraft.

Artist's concept of a DMSP satellite in orbit. Photo credit: Lockheed Martin Corp.
The $518 million satellite was successfully boosted into orbit from California's Vandenberg Air Force Base on Thursday on a United Launch Alliance Atlas 5 rocket.

The Atlas 5 rocket's Centaur upper stage released the 2,700-pound spacecraft into orbit 530 miles above Earth, beginning a two-month sequence of activations and tests for the satellite's systems and weather sensors.

The spacecraft is part of the U.S. Air Force's Defense Meteorological Satellite Program, which collects weather data from polar orbit to help forecasters produce forecasts for military and civilian users.

The satellite apparently hit a snag in one of its first post-launch tasks when it unfurled its solar array.

Kathryn Sullivan, administrator of NOAA, said Friday that controllers were sorting out a problem with the solar array boom.

"It's about 30 degrees shy of full deploy on the solar array boom, but we're not working that as a contingency, so we'll see how that goes," Sullivan told the National Research Council's Space Studies Board on Friday.

Sources familiar with the situation said spacecraft operations are currently not affected by the issue with the solar array boom. They said DMSP 19 is safe, stable and has sufficient power to proceed with early orbit testing, and a special team has been appointed to evaluate the problem.

The satellite's solar array includes ten flat structurally identical solar cell panels, according to a technical report issued in 2006 by the Aerospace Corp. on long-term storage of DMSP solar panels.

The panels are assembled into two packages of five panels. When unfurled in orbit, the ten panels are arranged in a single plane around the solar array boom, allowing the panels to track the sun as the spacecraft flies around Earth, engineers wrote in the Aerospace Corp. report.

Once operational, DMSP 19 will be controlled by a joint NOAA and Air Force team at NOAA's satellite operations center in Suitland, Md.

Built by Lockheed Martin Corp., the DMSP 19 spacecraft is the latest in a 52-year series of military weather satellites.

It was finished in 1998 and put into long-term storage to be launched when the Air Force deemed it needed the satellite in orbit to replace aging platforms.

Engineers put DMSP 19 through two lifetime extension efforts to raise its in-space life expectancy, upgraded its star trackers and installed a digital gyroscope to improve navigation in orbit. They also replaced materials and lubricants that degraded during storage.

The satellite is fitted with sensors to collect visible and infrared imagery of clouds, measure precipitation, surface temperatures and soil moisture, identify and locate severe weather, form three-dimensional cloud analyses, and monitor space weather, according to a Lockheed Martin fact sheet.

Along with NOAA's own civil weather satellites and European polar-orbiting meteorological observatories, the Air Force's DMSP constellation feeds data to international forecasters to track global storm systems.

DMSP 19 is the penultimate spacecraft in the DMSP series. The remaining satellite on the ground is in storage while Air Force officials decide whether to launch it in a few years or mothball it and move ahead with a newer, smaller and less costly weather satellite system.

With DMSP 19's launch, the military's polar-orbiting weather satellite system includes seven operating spacecraft. The satellite is designed for a five-year lifetime in orbit.