The University of Colorado at Boulder has been selected by NASA's Earth Science Office to conduct a $22.8 million satellite mission to measure the effects of the sun's radiation on Earth and its atmosphere.
The mission is part of NASA聮s Earth Observing System, a cadre of orbiting platforms and satellites designed to study Earth, including its reponse to incoming solar radiation. Known as the Total Solar Irradiance Mission, or TSIM, the CU-Boulder project is being directed by Senior Research Associate Gary Rottman of the Laboratory for Atmospheric and Space Physics.
"We are very excited, because this project will complement research CU faculty and students have conducted on the sun for the past three decades," he said. "TSIM will cover the full range of solar radiation that affects Earth."
Solar radiation is the dominant energy input into the Earth's ecosystem, and even small changes in the sun's output can produce significant changes in Earth's climate and environment, he said.
"Only by measuring and understanding the sun's natural variation can we determine how much of the atmospheric changes we see, like ozone depletion, are the result of human activity," Rottman said. "We will examine both direct and indirect mechanisms that may influence the Earth system, including ozone changes in the stratosphere."
LASP will build two state-of-the-art solar instruments for the TSIM mission to measure both total solar radiation and radiation separated by wavelength, or energy, said Rottman. The five-year mission will team LASP scientists with Orbital Sciences Corp. of Dulles, Va., which will provide the spacecraft, assist in the launch and support the operation of the spacecraft.
The mission operations for TSIM will take place at LASP's Space Technology Building in CU's Research Park, where researchers are now controlling the Student Nitric Oxide Explorer satellite launched in 1998 that involved the work of more than 100 students. The control center, directed by Randy Davis and manned by a number of students and faculty, also will be controlling QUIKSCAT, another NASA EOS mission.
"As with all LASP programs, TSIM will provide a unique opportunity for both students, faculty and staff," Rottman said. "Students are encouraged to participate in all phases of the programs, from instrument design and testing and satellite operations and control, to data analysis and scientific discovery."
LASP has had an active solar-monitoring program dating back to 1970 sounding rocket experiments. The program included the Solar Mesosphere Explorer satellite that flew in the 1980s, a joint venture between CU and Ball Aerospace and the first NASA satellite ever controlled by a university.
In addition, NASA's Upper Atmosphere Research satellite launched in 1991 is carrying a CU-Boulder instrument known as SOLSTICE. Under Rottman's direction, that instrument continues to gather data comparing the sun's ultraviolet output to an ensemble of about 30 stable nearby blue stars.
"We are tagging the sun to a set of astronomical standards that have been out there in the sky for a hundred million years," he said. "We will be able to refer back to these same stars in decades to centuries for comparison to see how our sun has changed. Such experiments help to build satellite data sets for future generations and help climate modelers."
Rottman will direct the instrument design and development of TSIM, including calibration and satellite operations. The project will be managed by Thomas Sparn. Other CU co-investigators on the project include George Lawrence, Jerald Harder, Thomas Woods, William McClintock and Julius London. In addition, co-investigators Oran White and Peter Fox from the National Center for Atmospheric Research will participate in the project.
All data returned to the TSIM spacecraft will be processed and analyzed at the LASP Data Processing Center at CU's Research Park, said Rottman.
Rottman also is the principal investigator on the SAVE mission, another of NASA's EOS projects. Slated for launch in 2002, the SAVE satellite will carry a more sophisticated version of CU's SOLSTICE instrument and will be controlled from the LASP Research Park facility.