Solar/Space Observation Satellites
POLAR
The Polar spacecraft was launched on February 24, 1996, to obtain data from both high- and low-altitude perspectives of this active region of geospace. High above the poles the particles of the solar wind and the energy of the wind can find their way into the magnetosphere. At lesser altitudes energy is transferred from electric fields and electromagnetic waves to electrons that then plunge into the atmosphere to create the aurora. At mid-altitudes nearer the equator the satellite passes through the Earth's trapped radiation, the Van Allen belts. Out of the polar ionosphere flows plasma to populate the magnetosphere. Through this region particles and energy flow from the geomagnetic tail to the atmosphere. Thus the instruments on the Polar satellites see a lot of action in the various plasma parameters that they measure. Three of the twelve scientific instruments aboard the Polar satellite are used to image the aurora in various wavelengths when the satellite is near apogee, high over the northern polar region. The other nine instruments make measurements in-situ, at the location of the satellite, around the entire orbit. They measure the fluxes of charged particles, electrons and protons, as well as heavier ions, from thermal energies into MeV energies. They measure magnetic and electric fields, plus electromagnetic waves. They must make these measurements in great detail in order for scientists to be able to learn new things about the environment in the region over the poles of the Earth. The Polar satellite is in a highly elliptical orbit, with apogee at 9 earth radii and perigee at 1.8 earth radii geocentric. The inclination is 86 deg. and the period about 18 hours. Initially apogee was over the northern polar region, but apogee has been moving towards the equator at about 16 deg. per year. The nominal mission duration was two years, but a three year extended mission has been approved. Details on the POLAR mission and instrumentation are provided in Space Science Reviews (Vol. 71, Nos. 1-4, 1995) and reprinted in The Global Geospace Mission, edited by C. T. Russell (Kluwer, 1995). For more information, see: http://pwg.gsfc.nasa.gov/polar/ Group: Platform_Details Entry_ID: POLAR Group: Platform_Identification Platform_Category: Solar/Space Observation Satellites Short_Name: POLAR Long_Name: POLAR End_Group Group: Synonymous_Platform_Names Short_Name: GGS/Polar Short_Name: STP/Polar Short_Name: Polar Plasma Laboratory Short_Name: 23802 Short_Name: 1996-013A Short_Name: POLAR-EFI End_Group Group: Platform_Associated_Instruments Short_Name: MDI Short_Name: VIS Short_Name: UVI Short_Name: TIMAS Short_Name: TIDE Short_Name: SEPS Short_Name: PWI-P Short_Name: PIXIE Short_Name: MFE-P Short_Name: HYDRA Short_Name: EPI Short_Name: CEPPAD Short_Name: CAMMICE End_Group Group: Orbit Orbit_Inclination: 85.9 degrees Period: 938.1 min Perigee: 185 km Apogee: 50551 km Orbit_Type: HEO > Highly Elliptical Orbit End_Group Online_Resource: http://pwg.gsfc.nasa.gov/polar/ Sample_Image: http://nssdc.gsfc.nasa.gov/image/spacecraft/polar.jpg Group: Platform_Logistics Launch_Date: 1996-02-24 Launch_Site: Cape Canaveral/Kennedy Space Center, USA Primary_Sponsor: NASA End_Group End_Group