NASA Jet Propulsion Laboratory, California Institute of Technology

NASA has selected Orbital Sciences Corporation, Dulles, VA, as the industry partner for the Active Cavity Radiometer Irradiance Monitor (ACRIM) satellite (ACRIMSAT), a solar- observing mission that is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA.

ACRIMSAT's is part of the Earth Observing System (EOS) and will study the Sun and its impact on the Earth's climate as part of a five-year mission. ACRIMSAT is set for launch in October 1999.

The $8.3 million contract to Orbital Sciences calls for the company to design, build and test the ACRIMSAT satellite. Under the contract, Orbital Science's responsibilities include the integration of the JPL-supplied ACRIM instrument with the satellite bus, environmental testing and supplying a redundant ground station to JPL. The satellite will be based on Orbital's flight-proven MiniStar satellite platform.

"ACRIMSAT will gather total solar irradiance on a daily basis and data products will be provided by the science team to NASA for use by the scientific community. I am pleased that JPL and OSC, as partners, will be instrumental in extending the long- term total solar irradiance data base through the next solar maxima," said Ronald Zenone, the ACRIMSAT project manager at JPL.

Sunlight provides the energy for many of Earth's atmospheric processes, but the Sun's radiant output fluctuates during an 11- year cycle, from a maximum to a minimum and back again. There are also short-term variations within that 11-year cycle of the 27- day solar rotation period. Earth's atmosphere is influenced by both cycles, which makes the total solar irradiance coming from the Sun the primary driver of the Earth's climate.

JPL, a division of the California Institute of Technology, will manage the ACRIMSAT mission for NASA's Office of Mission to Planet Earth, Washington, DC.

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