NPP Satellite Wraps Up Environmental Test Campaign

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WASHINGTON — The first of a new generation of polar-orbiting U.S. weather satellites completed a seven-month environmental test campaign April 27 and is on track for a planned Oct. 25 launch, government and industry officials said May 17.

The satellite — known as the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP) — will be tasked with demonstrating five new weather and climate instruments and a new ground system while ensuring data continuity for 27 Earth observation measurements, officials said during a media teleconference.

The NPP satellite was originally conceived in 1998 as a demonstration platform for instruments that were planned to fly on NPOESS, a now-defunct satellite program that was intended to replace separate military and civilian weather forecasting constellations. The $1.5 billion satellite was developed by NASA on behalf of the Defense Department and National Oceanic and Atmospheric Administration (NOAA).

The NPP spacecraft was built and integrated by Ball Aerospace & Technologies Corp. of Boulder, Colo., which also developed its Ozone Mapping and Profiler Suite instrument. It was planned for launch as early as 2006 but was held up by numerous technical troubles, most notably development of the Visible Infrared Imager Radiometer Suite built by Raytheon Space and Airborne Systems of El Segundo, Calif. The satellite also hosts the Cross-track Infrared Sounder, built by Northrop Grumman Electronic Systems of Azusa, Calif.; and the Advanced Technology Microwave Sounder and Clouds and the Earth Radiant Energy System instruments, both built by Northrop Grumman Aerospace Systems of Los Angeles.

The NPOESS program’s costs soared during its protracted development phase, leading to a program restructuring in 2006. In 2009, program officials decided NPP would have to take on an operational role. While no changes to the satellite itself were needed, work on some of the ground systems and data products had to be accelerated, said Ken Schwer, NPP project manager at NASA’s Goddard Space Flight Center in Greenbelt, Md.

In February 2010, the White House announced the NPOESS program would be dismantled. NOAA and NASA were directed to begin work on a new civil weather satellite system, known as the Joint Polar Satellite System, while the Pentagon was to pursue its own military weather satellites. The first of the new civil weather satellites, now planned for launch in 2016, will also be built by Ball Aerospace and carry the same five instruments as NPP.

The NPP spacecraft passed its environmental test campaign with flying colors and requires no rework, Schwer said. Over the next few months, Ball Aerospace will perform postenvironmental instrument testing, another satellite-ground system compatibility test and a final mission rehearsal before integrating the satellite’s solar arrays and conducting a final preshipment review, said Scott Tennant, Ball Aerospace’s NPP program manager, in an emailed response to questions. Then in August the 2,025-kilogram spacecraft will be shipped to Vandenberg Air Force Base, Calif., for what will be the last planned launch for the Delta 2 rocket that has been NASA’s workhorse for the past two decades.

NPP will be carried to an 824-kilometer-high polar orbit, where it will circle the globe 14 times per day, downlinking its data and receiving commands from a single ground station in Norway. The satellite will join on orbit and eventually replace NOAA’s N-Prime satellite that was launched in 2009, said Jim Gleason, the NPP project scientist at Goddard. NPP will undergo a 90-day checkout and evaluation phase with the goal of using data from all five of its sensors operationally within one year, Gleason said. The requirement is for all data to be validated for operational use within 18 months.

NPP has three missions: weather, short-term environmental observations and long-term climate measurements, Gleason said. There are 13 environmental measurements for which the United States has at least 20 years of continuous observation from space, such as levels of ozone, he said. Another 14 measurements have been collected for nearly a decade by NASA’s Aqua and Terra spacecraft.

“We’re trying to get a sense of what is changing on the planet and how it’s changing, in a quantitative sense,” Gleason said.