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New Satellite to Soak Up Sun Rays - 2003-01-25

A new U.S. spacecraft has been launched from Florida on a mission to soak up the sun's rays, like a vacationer at the beach. But no one would consider the place it is heading to be a vacation spot, more than 600 kilometers into frigid space. The satellite will help us understand how solar radiation influences our climate.

The sun, the sustenance of our life, may be the most observed star, and yet another U.S. satellite is going to watch it intently.

A fleet of U.S., European, and Japanese spacecraft has been watching the sun for years, gathering data on particular features on its surface or measuring the flux of high speed charged solar particles that bombard our planet and sometimes play havoc with our telecommunications and electrical power.

Only a few instruments on these veteran spacecraft measure the sun's radiation reaching Earth. So the new satellite will be devoted entirely to that task with the benefit of newer, more accurate technology.

"This particular investigation is trying to improve our understanding of the amount of solar energy coming into the Earth's environment and how that impacts the environment, said Donald Anderson, who manages the satellite for the U.S. space agency, NASA. "The importance of this in particular is that in order to understand the impacts of global change produced by mankind, we certainly need to understand how the sun is varying before we can make that assessment."

The mission is called the Solar Radiation and Climate Experiment, abbreviated as SORCE. Launched from a rocket dropped from an aircraft off Florida's Atlantic coast, SORCE will monitor changes in the amount of sunlight reaching Earth. It will also employ instruments to break sunlight down into several wavelengths, according to the chief scientist for the mission, Gary Rottman of the University of Colorado.

"We have spectrometers to measure each of the various colors from the sun and understand how those vary as well," said Mr. Rottman. "Those different colors - the X-rays [and] the ultraviolet get absorbed very high in the Earth's atmosphere. The longer radiation, the visible [and] near infrared, penetrates low in the atmosphere all the way to the surface."

The sun influences everything about Earth's climate, from droughts and ozone loss to human health problems like skin cancer and cataracts. Mr. Rottman says the SORCE spacecraft's long term solar radiation data will help scientists make more accurate computer models of Earth's climate to aid the understanding of its variability.