| definition
| - 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 (en)
|