A Sunpower M77 cryocooler cools the detectors aboard the NASA RHESSI satellite, which was launched in February 2002. The cryocooler maintains the detectors at the required operating temperature of minus 324 degrees Fahrenheit (minus 198 degrees Centigrade, or 75 degrees above absolute zero). The M77 has been operating flawlessly on RHESSI since February of 2002.
Researchers believe that much of the energy released during a solar flare is used to accelerate, to very high energies, electrons (emitting primarily X-rays) and protons and other ions (emitting primarily gamma rays).
The approach of the Reuven Ramaty High Energy Solar Spectronoscope Imager (RHESSI) mission was to combine, for the first time, high-resolution imaging in hard X-rays and gamma rays with high-resolution spectroscopy, so that a detailed energy spectrum could be obtained at each point of the image. This new approach will enable researchers to find out where these particles are accelerated and to what energies. Such information will advance understanding of the fundamental high-energy processes at the core of the solar flare problem.
RHESSI involved a single instrument consisting of an imaging system mounted in a simple Sun-pointed, spin-stabilized spacecraft. RHESSI investigated the physics of particle acceleration and energy released in solar flares. Observations were made of X-rays and Gamma-rays with energies from 3 keV to 20 MeV with an unprecedented combination of high-resolution imaging and spectroscopy.
RHESSI was launched aboard a Pegasus XL rocket, which was released from the bottom of an L-1011 plane and placed into a 600 km circular orbit inclined at 38 degrees with respect to the equator from Kennedy Space Center in Florida.
For a virtual tour, go to http://cse.ssl.berkeley.edu/hessi_epo/html/tour.html
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