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 (en)