Past Due NPOESS Sensor Finally Completes Testing

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The sensor blamed for delaying the U.S. civil-military National Polar-orbiting Operational Environmental Satellite System (NPOESS) completed testing in late October and is packed up waiting to be shipped to the spacecraft integrator, according to a Nov. 30 Northrop Grumman press release.

The first Visible Infrared Imaging Radiometer Suite (VIIRS) sensor, built by Raytheon Space and Airborne Systems of El Segundo, Calif., completed 112 days of thermal vacuum testing in which it was subjected to the temperature extremes it will experience in space, the release said. Northrop Grumman Aerospace Systems is the prime contractor for NPOESS.

The first VIIRS sensor will fly in 2011 on the NPOESS Preparatory Project satellite that is being built by Ball Aerospace & Technologies Corp. of Boulder, Colo. Raytheon is now building the second VIIRS sensor that will fly on the first NPOESS satellite, dubbed Charlie 1, which is slated for launch in mid-2014. That sensor will be delivered in 2011, Raytheon has said.

VIIRS is the most complex NPOESS instrument, designed to collect measurements of the atmosphere, clouds, land and sea in nearly two dozen spectral bands. The first sensor will lack some of the ocean-color monitoring capabilities it was designed for, but Raytheon says the partially redesigned second sensor will enable it to meet the full set of requirements.