An $88 million NASA satellite designed and built by the University of
Colorado at Boulder launched in late January 2003 to study variations
in the sun is performing flawlessly after more than a year in orbit,
scientists say.

Launched aboard a Pegasus XL rocket from the Kennedy Space Center in
Cape Canaveral, Fla., the Solar Radiation and Climate Experiment, or
SORCE, was developed to study how and why variations in the sun
affect Earth’s atmosphere and climate.

The SORCE satellite, part of NASA’s Earth Observing System, is
collecting a long-term data set of natural solar variation as a tool
to determine the role the sun plays in global change, said Senior
Researcher Gary Rottman of CU-Boulder’s Laboratory for Atmospheric
and Space Physics, or LASP. Rottman is the principal investigator on
the mission.

“The spacecraft and instruments all have been performing beautifully
since launch, and the new solar data have exceeded our expectations,”
Rottman said. “The sun also has cooperated and put on an unusual
display of intense activity in late October 2003, providing some of
the largest sunspots ever recorded and producing major flares
surpassing all previous observations.”

The unexpected phenomena will help scientists better understand how
the sun functions and influences Earth’s terrestrial environment,
said Rottman. Scientists and students at CU-Boulder are using data
from SORCE, along with information from other satellites, to
understand climate change, climate prediction, atmospheric ozone and
ultraviolet-B radiation.

Accurate knowledge of the sun’s variations at all light wavelengths
that may be heating Earth’s atmosphere, land and oceans is an
essential step to understanding, modeling and predicting impacts of
the sun on Earth.

“The science team is tremendously excited as the new observations are
incorporated into our understanding of the sun,” said Rottman. “We
want to understand the sun’s influence on Earth’s atmosphere and
climate so that we can more reliably determine how humans are
changing the environment.”

SORCE has greatly extended the spectral coverage with improved
accuracy, covering wavelengths from soft x-ray bands and ultraviolet
light through the visible and near-infrared spectral bands. This
provides the first extensive infrared solar irradiance measurements
from space, Rottman said.

“For the very first time we have observations capable of
characterizing the variations in the visible and near-infrared part
of the solar electromagnetic spectrum that are the dominant
contributors to the sun’s total energy that reaches the Earth’s
surface,” said Research Physicist Judith Lean of the Naval Research
Laboratories in Washington, D.C.

A performance evaluation of the SORCE mission last June by NASA rated
it excellent in all categories, including quality, timeliness, cost
and leadership, the highest ratings given. “LASP’s commitment to
mission success and their ability to work with NASA and industry
exemplify how Principal Investigator Mode missions should be
conducted in the future,” wrote the evaluators.

“It is unusual for a project of this kind to score the highest
possible points on a NASA evaluation,” said SORCE Program Manager Tom
Sparn of LASP. “Less than 4 percent of missions get excellent
ratings across the board.

“Never have measurements of the sun achieved this quality,” Sparn
said. “The sun is a very stable source of light, and we are
monitoring it at the most sensitive levels possible with today’s
technology.”

CU scientists and engineers designed, built, calibrated and tested
the four science instruments on the satellite. LASP subcontracted
with Orbital Sciences Corp. for the spacecraft launch on the Pegasus
Rocket.

LASP’s Mission Operations Center Director, Randy Davis, said CU staff
and students are operating the spacecraft over its five-year mission
life, acquiring, managing, processing and distributing science data.

“SORCE is a wonderful example of how NASA, universities and industry
can partner together,” said Bill Ochs, SORCE’s project manager at
NASA’s Goddard Space Flight Center in Greenbelt, Md. “In addition,
the student involvement from CU in the instrument development and
mission operations provides a great training ground for the aerospace
engineers of the future.”

For more information, see:
http://lasp.colorado.edu/sorce/news_letter.html.

Contact: Gary Rottman, (303) 492-8324
Tom Sparn, (303) 492-2475
Jim Scott, (303) 492-3114