WASHINGTON, D.C. (March 20, 2002) -- Just in time for Sun-Earth Day, a new NASA spacecraft, complete with a new name, made its debut by observing a huge explosion in the atmosphere of the Sun. The blast, called a solar flare, was equal to one million megatons of TNT and gave off powerful bursts of X-rays.
The solar fireworks were captured by what is now known as the Reuven Ramaty High-Energy Solar Spectroscopic Imager spacecraft, or RHESSI. The spacecraft launched last month as HESSI was recently renamed in honor of Dr. Reuven Ramaty, who died in 2001 after a long and distinguished career in the Laboratory for High Energy Astrophysics at the NASA Goddard Space Flight Center, Greenbelt, Md. Ramaty was a pioneer in the field of solar-flare physics, gamma-ray astronomy and cosmic rays.
"We are thrilled to be making the first high-resolution movies of flares using their high-energy radiation," said Brian Dennis, the RHESSI mission scientist at Goddard. "We want to understand how solar flares can explosively release so much energy. RHESSI shows us the high-energy radiation emitted by flares: their X-rays and gamma rays. This radiation reveals the core of the flare -- the exact time and place where the energy is released."
Today is the second annual Sun-Earth Day, which is sponsored by NASA's Sun-Earth Connection Education Forum to provide an opportunity to learn more about the Sun's connection to the Earth through images, cultural parallels and activities. Powerful events on the Sun, including flares, occasionally disrupt satellites and communications and power systems.
Scientists believe solar flares are powered by the violent release of magnetic energy, but how this happens is unknown. A new movie features one of the first flares recorded by RHESSI, which occurred Feb. 20 in the southern hemisphere of the Sun, an active region designated "AR 9830."
It was a moderately powerful flare, classified as M2.4 by the National Oceanic and Atmospheric Administration (NOAA). The most powerful flares, designated X-class by NOAA, can release up to 1,000 times more energy. During its planned two-year mission, RHESSI will study the secrets of how solar flares are produced in the Sun's atmosphere. Launched Feb. 5, RHESSI is now fully operational after only six weeks in orbit. It is observing the Sun and recording the high-energy radiation from solar flares as they occur.
RHESSI is the first NASA Small Explorer mission being managed in the "Principal Investigator" mode. The Principal Investigator, Robert Lin of the University of California, Berkeley, is responsible for most aspects of the mission, including the science instrument, spacecraft integration and environmental testing, and spacecraft operations and data analysis.
The RHESSI scientific payload is a collaborative effort among the University of California, Berkeley; Goddard; the Paul Scherrer Institut in Switzerland; and the Lawrence Berkeley National Laboratory in Berkeley. The mission also involves additional scientific participation from France, Japan, The Netherlands, Scotland and Switzerland.
The Explorers Program Office at Goddard manages the RHESSI mission for NASA's Office of Space Science in Washington. Spectrum Astro, Inc. of Gilbert, Ariz., constructed the RHESSI spacecraft and provided integration support.
A movie of the flare recorded by the RHESSI spacecraft is available on the Internet at:http://www.gsfc.nasa.gov/topstory/20020320hessixray.html
RHESSI data are now available online to the general public at:http://hesperia.gsfc.nasa.gov/hessi/
More information about Sun-Earth Day can be found on the World Wide Web at:http://sunearth.gsfc.nasa.gov.sunearthday
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