POLAR
type: Concept
in scheme: platforms
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 Scienc…

Solar/Space Observation Satellites
type: Concept