MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
AcrimSat Mission Status
December 21, 1999
NASA’s Active Cavity Radiometer Irradiance Monitor
(AcrimSat) — a satellite designed to measure the total amount of
sunlight falling on Earth’s atmosphere, oceans and land, and
improve predictions of long-term climate change — lifted off at
11:13 p.m. Pacific Standard Time December 20 aboard a Taurus
rocket.
The night launch from Space Launch Complex 576 East at
Vandenberg Air Force Base, CA, begins a five-year science mission
to monitor incoming solar radiation and help scientists determine
whether an increase in sunlight is contributing to a rise in
global temperatures. The Active Cavity Radiometer Irradiance
Monitor sun sensor, managed by NASA’s Jet Propulsion Laboratory,
Pasadena, CA, is the third in a series of missions to measure
variations in total incoming solar energy, known as total solar
irradiance.
The solar-monitoring satellite, a secondary payload riding
along with the primary Korea Multi-Purpose Satellite, was
deployed 16 minutes after launch, at 11:29 p.m., some 90 seconds
after the primary satellite was released. Ground controllers at
the McMurdo Ground Station in Antarctica acquired AcrimSat’s
signal about 20 minutes after launch, at about 11:33 p.m. The
115-kilogram (253-pound) satellite is currently circling Earth
from a polar orbit at an altitude of 685 kilometers (425 miles).
The satellite operations team will monitor spacecraft
health, including AcrimSat’s operating temperature, state of
battery charging, Sun-pointing performance and the overall
condition of all onboard systems in the next two weeks. Once all
systems have been checked, instrument checkouts will be conducted
to assure normal performance of the sun sensors before science
operations begin.
The Active Cavity Radiometer Irradiance Monitor instrument
is managed by JPL for NASA’s Office of Earth Sciences,
Washington, DC. Columbia University’s Science Computing Facility,
Coronado, CA, will oversee science operations. The primary ground
station is located at JPL’s Table Mountain Observatory,
Wrightwood, CA. Orbital Sciences Dulles, MD, built the Taurus
launch vehicle and Active Cavity Radiometer Irradiance Monitor
satellite. NASA’s Jet Propulsion Laboratory is a division of the
California Institute of Technology, Pasadena, CA.
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