Solar/Space Observation Satellites
RHESSI
The High Energy Solar Spectroscopic Imager (HESSI) mission consists of a single spin-stabilized spacecraft in a low-altitude orbit inclined 38 degrees to the Earth's equator. The only instrument on board is an imaging spectrometer with the ability to obtain high fidelity color movies of solar flares in X rays and gamma rays. It uses two new complementary technologies: fine grids to modulate the solar radiation, and germanium detectors to measure the energy of each photon very precisely. The HESSI was renamed the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). RHESSI is a NASA Small Explorer satellite and was launched February 5, 2002. RHESSI's imaging capability is achieved with fine tungsten and/or molybdenum grids that modulate the solar X-ray flux as the spacecraft rotates at ~ 15 rpm. Up to 20 detailed images can be obtained per second. This is sufficient to track the electrons as they travel from their acceleration site, believed to be in the solar corona, and slow down on their way to the lower solar atmosphere. The high-resolution spectroscopy is achieved with 9 cooled germanium crystals that detect the X-ray and gamma-ray photons transmitted through the grids over the broad energy range of 3 keV to 20 MeV. Their fine energy resolution of about 1 keV is more than sufficient to reveal the detailed features of the X-ray and gamma-ray spectra, clues to the nature of the electron and ion acceleration processes. For more information, see; http://hesperia.gsfc.nasa.gov/hessi/index.html Group: Platform_Details Entry_ID: RHESSI Group: Platform_Identification Platform_Category: Solar/Space Observation Satellites Short_Name: RHESSI Long_Name: Reuven Ramaty High Energy Solar Spectroscopic Imager End_Group Group: Synonymous_Platform_Names Short_Name: HESSI Short_Name: Reuven Ramaty High Energy Solar Spectroscopic Imager Short_Name: SMEX/RHESSI Short_Name: Small Explorer/RHESSI Short_Name: 27370 Short_Name: 2002-004A End_Group Group: Platform_Associated_Instruments Short_Name: HESSI SPECTROMETER Short_Name: HESSI IMAGER End_Group Group: Orbit Orbit_Altitude: 600 km Orbit_Inclination: 38 degrees Period: 96.5 m Perigee: 579 km Apogee: 607 km Orbit_Type: LEO > Low Earth Orbit > Polar Sun-Synchronous End_Group Online_Resource: http://hesperia.gsfc.nasa.gov/hessi/ Sample_Image: http://hesperia.gsfc.nasa.gov/hessi/images/hessicraft.gif Group: Platform_Logistics Launch_Date: 2002-02-05 Launch_Site: Cape Canaveral/Kennedy Space Center, USA Design_Life: 2 years Primary_Sponsor: NASA/GSFC End_Group End_Group