Faulty Solar Panel Mechanism Delays Launch of Glory Satellite Another 3 Months


WASHINGTON — Launch of NASA’s Glory satellite, which is designed to monitor solar radiance and particulates in Earth’s atmosphere, has been delayed an additional three months to February 2011 by a faulty mechanism in the motor that drives one of the spacecraft’s solar arrays, a NASA official said Oct. 7.

The $424.1 million Glory satellite was most recently scheduled for launch in November following a 13-month delay that was the result of both satellite hardware problems and the need to correct issues with its Taurus launch vehicle, which failed in its last launch attempt. The satellite is being built and launched by Orbital Sciences Corp. of Dulles, Va., and uses a spacecraft platform originally built for the Vegetation Canopy Lidar mission NASA canceled in 2001.

Glory was undergoing thermal vacuum testing at Orbital Sciences’ facilities in late 2009 when the first problem with the craft’s solar array drive assembly was detected, Glory Program Executive Joy Bretthauer said in an interview. Additional testing was performed at that time and the anomaly could not be replicated. This June, however, the problem resurfaced during testing and became chronic, and the decision to replace a faulty mechanism was made in late August, Bretthauer said.

Moog Components Group of Blacksburg, Va., built the failed component, a slip ring that allows the solar array to rotate while transmitting data and power. NASA is pursuing parallel paths to replace the component, with Moog and at least one other company working on new slip rings. A decision on which to use will be made next month, Bretthauer said. The Glory program has enough reserve funds to manage the situation within its current budget, she said.

Once launched, Glory will be placed into NASA’s so-called A-train polar orbit, joining five other NASA Earth observation satellites flying in relatively close proximity. The satellite features the Aerosol Polarimetry Sensor, built by Raytheon Space and Airborne Systems of El Segundo, Calif., that will provide measurements of black carbon soot and other atmospheric particles associated with climate change. The satellite also carries the Total Irradiance Monitor, built by the University of Colorado’s Laboratory for Atmospheric and Space Physics. That sensor is meant to continue NASA’s uninterrupted 30-year history of observing solar energy output. Those observations are currently provided by the Solar Radiation and Climate Experiment spacecraft, a nearly 8-year-old satellite that has surpassed its design life and could fail at any time, Bretthauer said. Despite operating beyond its design life, however, there are no known problems indicating the mission is at risk.

Glory will be launched on an Orbital Sciences-built Taurus XL rocket, making its return to flight some 24 months after a failure that destroyed NASA’s Orbiting Carbon Observatory (OCO) spacecraft. NASA identified four possible causes for the failure of the Taurus XL rocket. During that launch, a faulty pressure indicator prevented the payload faring from separating, causing the satellite to re-enter the atmosphere and plummet into the Indian Ocean near Antarctica. Orbital bore most of the cost associated with the rocket’s return to flight activities, Bretthauer said. Orbital spokesman Barry Beneski was unable to provide details of the return to flight activities or their cost by press time.

At the time of the OCO failure, Glory was slated for an October 2009 launch. Concurrent with the delay caused by the Taurus failure, Glory also experienced payload interface processor problems that required the purchase and integration of new hardware. Replacement of the satellite’s Maxwell SCS750 computer with a BAE Rad750 computer and the associated integration and test activities added $45 million to the program’s cost, NASA budget documents show.