Raytheon Space and Airborne Systems (SAS) is under contract to design and develop the Visible Infrared Imaging Radiometer Suite (VIIRS) EDU and seven flight units for NPOESS prime contractor Northrop Grumman Corp.

The EDU recently completed ambient testing and vibration testing, the first and second phases of system-level tests designed to ensure that the sensor will perform as intended and withstand the rigors of operation in space. The series of performance and environmental tests on the EDU, which is built using the same standards and processes that will be used for the flight units, proves the processes used to design and manufacture the sensor are sound.

In another test, the EDU's passive cooling system, consisting of the cryo-radiator and other passive cooling elements, demonstrated better-than-required performance during thermal vacuum testing. This cooling system supports the sensor's infrared focal plane arrays, which are responsible for gathering imaging data.

"As a company committed to delivering systems our customers know will work every time all the time, passing these critical milestones is a significant step toward ensuring the operational performance of VIIRS," said SAS President Jon Jones. "Our goal is to provide the most advanced weather sensor ever made."

VIIRS will collect visible/infrared imagery and radiometric data on the atmosphere, clouds, earth radiation budget, clear-air land/water surfaces, sea surface temperature, ocean color, and low-light visible imagery. The sensor will offer dramatic spatial, spectral and radiometric performance improvements compared with current operational capabilities.

"These successful tests, especially the vibration test, demonstrate the risk reduction effort on VIIRS is working effectively," said Alexis Livanos, president, Northrop Grumman Space Technology. "Northrop Grumman, Raytheon and our customer have worked very closely to develop this advanced capability. The recent successes make a strong statement about the dedication of the team to the entire NPOESS mission."

The next step is thermal vacuum testing in one of Raytheon's space-qualified thermal vacuum chambers. The chamber, also used to verify the performance of Raytheon instruments such as MODIS (Moderate Resolution Imaging Spectroradiometer) operating on NASA's Terra and Aqua spacecraft, replicates the extreme heat and freezing cold cycles spacecraft and sensors experience in space.

The EDU is scheduled for delivery later this year. Delivery of the first VIIRS flight unit is scheduled for 2008.

NPOESS, the nation's next-generation, low-earth-orbit environmental satellite system, is composed of satellites, sensors, a ground-control system and a data processing and dissemination network. NPOESS will provide civilian, military and scientific communities with regional and global meteorological data; oceanographic, environmental, climatic, and space environmental remote sensing information; surface data collection and search and rescue capabilities.

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