@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix ns0: <http://gcmd.gsfc.nasa.gov/kms#> .

<https://gcmd.earthdata.nasa.gov/kms/concept/8e8b7689-0a8e-47a4-9c68-5f6a207104d5>
  skos:prefLabel "Solar/Space Observation Satellites"@en ;
  a skos:Concept ;
  skos:narrower <https://gcmd.earthdata.nasa.gov/kms/concept/ac6d0fd3-a559-4f59-b862-51addf61944a> .

<https://gcmd.earthdata.nasa.gov/kms/concept/ac6d0fd3-a559-4f59-b862-51addf61944a>
  ns0:resource [ ] ;
  ns0:altLabel [ ] ;
  skos:definition """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 ;
  skos:prefLabel "RHESSI"@en ;
  skos:inScheme <https://gcmd.earthdata.nasa.gov/kms/concepts/concept_scheme/platforms> ;
  skos:broader <https://gcmd.earthdata.nasa.gov/kms/concept/8e8b7689-0a8e-47a4-9c68-5f6a207104d5> ;
  a skos:Concept .