| February 19, 2004
NASA’s SORCE Satellite Celebrates One Year of Operations
Having marked its first anniversary on orbit, NASA’s Solar Radiation
and Climate Experiment (SORCE) satellite has hit its stride. In concert
with other satellites, SORCE’s observations of the sun’s
brightness are helping researchers better understand climate change,
climate prediction, atmospheric ozone, the sunburn-causing ultraviolet-B
radiation and space weather.
In fall 2003, SORCE was fortunate to see and measure exceptionally high
levels of the sun’s activities. In late October and November the
sun sent solar flares and coronal mass ejections hurtling Earthward,
disrupting satellites and other transmissions, triggering an intense
geomagnetic storm, and enabling sightings of the northern lights as far
south as Arkansas, Texas and Oklahoma.
The third most powerful solar flare ever observed in X-rays, high-energy
photons with very short wavelengths, erupted from Sunspot 486 October
28, 2003, at approximately 6 a.m. Eastern Standard Time. The same spot
released a large X11 flare on the afternoon of October 29. As the sunspot
moved across the face of the sun, total solar brightness decreased by
0.3 percent.
SORCE tracked the decreases in Total Solar Irradiance (TSI) and the
increases in X-rays, as well as changes in the other parts of the solar
spectrum. SORCE’s suite of instruments measures solar brightness
in soft X-ray bands and at wavelengths from ultraviolet through the visible
and near-infrared spectrum. This is the most comprehensive dataset ever
collected of the complex brightness changes that occur in the solar spectrum
during a major eruptive event.
Having accurate knowledge of the sun’s brightness variations on
all time scales, from flares to centuries, at all wavelengths heating
the Earth’s atmosphere, land and oceans is essential to understand,
model and predict impacts of the sun on Earth.
Two of the SORCE instruments, the Total Irradiance Monitor (TIM) and
the Spectral Irradiance Monitor (SIM), will ultimately be part of the
operational measurements made by the National Polar-orbiting Operational
Environmental Satellite System (NPOESS) satellites beginning in 2013.
Solar irradiance has been monitored since the 1970s to create a long-term
record for study by researchers.
“The spacecraft and instruments have all been performing beautifully
since launch, and the new solar data exceed all of our expectations,” said
Gary Rottman, SORCE Principal Investigator at University of Colorado’s
Laboratory for Atmospheric and Space Physics (LASP) in Boulder, Colorado. “The
sun also cooperated by putting on an unusual display of intense activity
in late October that provided some of the largest sunspots ever recorded
and produced major flares surpassing all previous observations. These
unexpected phenomena will help us better understand how the sun functions
and how it influences the terrestrial environment.”
“For the very first time we have observations capable of characterizing
simultaneously the variations in the total solar irradiance and in the
visible and near infrared part of the solar electromagnetic spectrum
that provides the primary energy to the Earth’s surface,” said
Dr. Judith Lean, Research Physicist at the Naval Research Laboratories
and a member of the National Academy of Sciences. “Simple models
exist of solar spectrum variability, which general circulation models
use to simulate climate response to solar forcing. SORCE data already
indicate the models need to be revised at infrared wavelengths; they
promise unprecedented new understanding of the mechanisms of solar spectral-irradiance
variability and their possible climatic impacts.”
SORCE is a joint partnership between NASA and LASP. As a principal investigator-led
mission, NASA provided management oversight and engineering support.
Scientists and engineers at the University of Colorado designed, built,
calibrated and tested the four science instruments on the satellite.
The Mission Operations Center and the Science Operations Center are both
located at the University.
For information about the SORCE mission in the Internet, visit:
http://www.nasa.gov
http://www.gsfc.nasa.gov/topstory/2003/0106sorce.html
http://lasp.colorado.edu/sorce/
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Contacts:
David E. Steitz
Headquarters, Washington
Phone: 202/358-1730
Lynn Chandler
Goddard Space Flight Center, Greenbelt, Md.
Phone: 301/286-2806 |
|
Recent Observations
SORCE recorded the most comprehensive dataset ever of the complex changes
- namely total solar brightness decrease by a whopping 3 tenths of one
percent during the period of record-setting solar flares in October/November.
Credit: NASA
Record-Breaking Flares from Sun
On Oct. 28 spacecraft tracked an unusually fast-moving X-17.2 sized flare
- the second largest ever observed by SOHO. The spot blasted off two
more flares including a record-setting X-28 on Nov. 4.Credit: NASA /
ESA
Tracking the Solar Spectrum
SORCE measures the wavelengths of the energy reaching the Earth from
the Sun. Credit: NASA
Down to Earth: Solar Rays
Only about 70% of the solar energy that reaches Earth is absorbed, while
the other 30% is reflected back into space by atmosphere and aerosols,
ocean/land and clouds. Credit:NASA
A Slow Time - The Solar Cycle
We’re edging toward a tamer period of the Sun’s 11-year cycle,
with ‘solar max’ having occurred between 1999 and 2001. Credit:
NASA
SORCE Spacecraft
SORCE maintains a 24-year legacy of solar output monitoring that should
help explain and predict the effect of the Sun on the Earth’s atmosphere
and climate. Credit: NASA / LASP |
