 Polar is the second of NASA'sGlobal Geospace Science program | |||||||||||||||||||||||||
| Names | GGS/Polar, ISTP/Polar,Polar Plasma Laboratory | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mission type | Earth observation | ||||||||||||||||||||||||
| Operator | NASA | ||||||||||||||||||||||||
| COSPAR ID | 1996-013A | ||||||||||||||||||||||||
| SATCATno. | 23802 | ||||||||||||||||||||||||
| Website | http://pwg.gsfc.nasa.gov/polar/ | ||||||||||||||||||||||||
| Mission duration | Planned: 2 years Final: 12 years, 2 months, 3 days | ||||||||||||||||||||||||
| Spacecraft properties | |||||||||||||||||||||||||
| Manufacturer | Lockheed Martin Astro Space | ||||||||||||||||||||||||
| Launch mass | 1,297 kg (2,859 lb)[1] | ||||||||||||||||||||||||
| Dry mass | 1,028 kg (2,266 lb)[1] | ||||||||||||||||||||||||
| Payload mass | 264 kg (582 lb)[1] | ||||||||||||||||||||||||
| Dimensions | 2.4 × 1.8 m (7.9 × 5.9 ft)[1] | ||||||||||||||||||||||||
| Power | 440 watts[1] | ||||||||||||||||||||||||
| Start of mission | |||||||||||||||||||||||||
| Launch date | February 24, 1996, 11:24 (1996-02-24UTC11:24) UTC[2] | ||||||||||||||||||||||||
| Rocket | Delta II 7925-10 D233 | ||||||||||||||||||||||||
| Launch site | VandenbergSLC-2W | ||||||||||||||||||||||||
| End of mission | |||||||||||||||||||||||||
| Disposal | Decommissioned | ||||||||||||||||||||||||
| Deactivated | April 28, 2008 (2008-04-29)[3] | ||||||||||||||||||||||||
| Orbital parameters | |||||||||||||||||||||||||
| Reference system | Geocentric | ||||||||||||||||||||||||
| Regime | Highly elliptical | ||||||||||||||||||||||||
| Semi-major axis | 35,490.94 km (22,053.05 mi) | ||||||||||||||||||||||||
| Eccentricity | 0.701992 | ||||||||||||||||||||||||
| Perigee altitude | 4,198.46 km (2,608.80 mi) | ||||||||||||||||||||||||
| Apogee altitude | 54,027.15 km (33,570.91 mi) | ||||||||||||||||||||||||
| Inclination | 78.63° | ||||||||||||||||||||||||
| Period | 1,109.02 minutes | ||||||||||||||||||||||||
| RAAN | 260.60° | ||||||||||||||||||||||||
| Argument of perigee | 306.12° | ||||||||||||||||||||||||
| Mean anomaly | 7.84° | ||||||||||||||||||||||||
| Mean motion | 1.30° | ||||||||||||||||||||||||
| Epoch | August 19, 2018, 04:42:45 UTC[4] | ||||||||||||||||||||||||
| Revolutionno. | 10,771 | ||||||||||||||||||||||||
| |||||||||||||||||||||||||
TheGlobal Geospace Science (GGS)Polar satellite was aNASA science spacecraft designed to study the polarmagnetosphere andaurorae. It was launched into orbit in February 1996, and continued operations until the program was terminated in April 2008. The spacecraft remains in orbit, though it is now inactive.Polar is the sister ship toGGSWind.
It was designed and manufactured byLockheed Martin, and launched at 11:23:59.997 UTC on February 24, 1996, aboard aMcDonnell DouglasDelta II 7925-10 rocket from launch pad 2W atVandenberg Air Force Base inLompoc,California, to study the polarmagnetosphere.
The spacecraft was placed into a highly elliptical orbit withapogee at 9 Earth radii andperigee at 1.8 Earth radii (geocentric), 86 degrees inclination, with a period of around 18 hours. The apogee was initially over the northern polar region, but has since been precessing south at about 16° per year.
Sensors on the spacecraft gathered multi-wavelength imaging of theaurora, and measured the entry ofplasma into the polar magnetosphere and the geomagnetic tail, the flow of plasma to and from theionosphere, and the deposition of particle energy in the ionosphere and upperatmosphere.
The nominal mission duration was two years, but was extended several times.Polar Mission Operations were finally terminated on April 28, 2008, after the spacecraft depleted its remaining fuel.[5][3]
Polar is a cylindrical satellite of 2.4 meters in diameter and 1.8 meters in height built by the "Astro Space" division of Martin Marietta. WIND is a stabilized satellite rotation at a speed of 10 rpm about its axis which is maintained perpendicular to the plane of the ecliptic. A platform that serves as support for certain instruments (including imaging) require that their field of view is fixed is fixed to the top of the satellite and rotates in the opposite direction. Satellite walls are covered with solar cells that provide 440 watts of electricity including 186 W are used by the scientific instruments. The satellite has a mass of 1297 kg, including 269 kg of propellant and 264 kg payload. It is designed for a minimum lifetime of 2 years. Scientific data are stored on a digital recorder with a capacity of 1.3gigabits and transmitted at a rate between 56 and 512kb.Polar is the twin satellite ofWind.
Polar carried 11 scientific instruments totaling a mass of 264 kg:
Five instruments studying the localelectromagnetic fields atlow frequency:
Three instruments responsible for studying populations of particles associated with electromagnetic fields:
Three imagers responsible for providing a comprehensive view of the processes that interact with the upper atmosphere:
Polar collected images of auroras in multiplewavelengths. It also measured the amount of plasma used in the polar regions of the magnetosphere, the flow of the latter in the ionosphere and the entry of other charged particles in it and in the upper atmosphere. For the first time the entire sequence of events initiated by magnetic substorms to the generation of theaurora was observed in detail. Analysis of the collected data determined that solar storms deposited such an amount of energy in the ionosphere that it stretched to fill the magnetosphere completely.Polar instruments were used during the primary mission of theTHEMIS satellite between January and April for his study of magnetic tail.[1]
