# Polar (satellite)

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NASA science spacecraft which studied the polar magnetosphere until 2008

Polar Polar is the second of NASA's Global Geospace Science program Names GGS/Polar, ISTP/Polar, Polar Plasma Laboratory Mission type Earth observation Operator NASA COSPAR ID 1996-013A SATCAT no. 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 Vandenberg SLC-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] Revolution no. 10,771 Instruments MFE Magnetic Field Experiment EFI Electric Fields Instrument PWI Plasma Wave Instrument HYDRA Hot Plasma Analyzer Experiment TIDE/PSI Thermal Ion Dynamics Experiment/Plasma Source Investigation TIMAS Toroidal Imaging Mass-Angle Spectrograph CAMMICE Charge and Mass Magnetospheric Ion Composition Experiment CEPPAD Comprehensive Energetic-Particle Pitch Angle Distribution UVI Ultraviolet Imager VIS Visible Imaging System PIXIE Polar Ionospheric X-ray Imaging Experiment International Solar-Terrestrial Physics Science Initiative ← Wind SOHO →

The [Global Geospace Science](/source/Global_Geospace_Science) (GGS) ***Polar*** satellite was a [NASA](/source/NASA) science spacecraft designed to study the polar [magnetosphere](/source/Magnetosphere) and [aurorae](/source/Aurora). 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 to [GGS *Wind*](/source/Wind_(spacecraft)).

## Launch

It was designed and manufactured by [Lockheed Martin](/source/Lockheed_Martin), and launched at 11:23:59.997 UTC on February 24, 1996, aboard a [McDonnell Douglas](/source/McDonnell_Douglas) [Delta II](/source/Delta_II) 7925-10 rocket from launch pad 2W at [Vandenberg Air Force Base](/source/Vandenberg_Air_Force_Base) in [Lompoc](/source/Lompoc), [California](/source/California), to study the polar [magnetosphere](/source/Magnetosphere).

The spacecraft was placed into a highly elliptical orbit with [apogee](/source/Apogee) at 9 Earth radii and [perigee](/source/Perigee) 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.

## Operations

Sensors on the spacecraft gathered multi-wavelength imaging of the [aurora](/source/Aurora_(astronomy)), and measured the entry of [plasma](/source/Plasma_(physics)) into the polar magnetosphere and the geomagnetic tail, the flow of plasma to and from the [ionosphere](/source/Ionosphere), and the deposition of particle energy in the ionosphere and upper [atmosphere](/source/Atmosphere).

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]

## Characteristics

*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 1.3 [gigabits](/source/Gigabits) and transmitted at a rate between 56 and 512 [kb](/source/Kilobit). *Polar* is the twin satellite of *[Wind](/source/Wind_(spacecraft))*.

## Scientific instruments

*Polar* carried 11 scientific instruments totaling a mass of 264 kg:

Five instruments studying the local [electromagnetic fields](/source/Electromagnetic_field) at [low frequency](/source/Low_frequency):

- **MFE** ([Magnetic Field](/source/Magnetic_Field) Experiment)

- **EFI** ([Electric Fields](/source/Electric_Field) Instrument)

- **PWI** ([Plasma](/source/Plasma_(physics)) Wave Instrument)

- **HYDRA** (Hot Plasma Analyzer Experiment)

- **TIDE/PSI** (Thermal Ion Dynamics Experiment / Plasma Source Investigation)

Three instruments responsible for studying populations of particles associated with electromagnetic fields:

- **TIMAS** (Toroidal Imaging Mass Angle [Spectrograph](/source/Spectrograph))

- **CAMMICE** (Charge and Mass Magnetospheric Ion Composition Experiment)

- **CEPPAD** (Comprehensive Energetic Particle-Pitch Angle Distribution)

Three imagers responsible for providing a comprehensive view of the processes that interact with the upper atmosphere:

- **UVI** ([Ultraviolet](/source/Ultraviolet) Imager)

- **VIS** ([Visible](/source/Light) Imaging System)

- **PIXIE** (*Polar* [Ionospheric](/source/Ionospheric) [X-ray](/source/X-ray) Imaging Experiment)

## Results

*Polar* collected images of auroras in multiple [wavelengths](/source/Wavelength). 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 the [aurora](/source/Aurora) 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 the [THEMIS](/source/THEMIS) satellite between January and April for his study of magnetic tail.[1]

A time-lapse animation of aurorae over both Earth poles shows symmetries and simultaneous changes - the long-suspected aurora mirroring – in images from the Visible Imaging System (VIS).

This composite image contains the first picture of the Earth in X-rays, taken in March 1996 by *Polar*.

## References

1. ^ [***a***](#cite_ref-eoPortal_1-0) [***b***](#cite_ref-eoPortal_1-1) [***c***](#cite_ref-eoPortal_1-2) [***d***](#cite_ref-eoPortal_1-3) [***e***](#cite_ref-eoPortal_1-4) [***f***](#cite_ref-eoPortal_1-5) ["Polar"](https://directory.eoportal.org/web/eoportal/satellite-missions/p/polar). *eoPortal*. European Space Agency. Retrieved August 19, 2018.

1. **[^](#cite_ref-nssdc.orbit_2-0)** ["Polar"](https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1996-013A). *[NASA Space Science Data Coordinated Archive](/source/NASA_Space_Science_Data_Coordinated_Archive)*. NASA. March 21, 2017. Retrieved April 28, 2018.

1. ^ [***a***](#cite_ref-nasa20080428_3-0) [***b***](#cite_ref-nasa20080428_3-1) Layton, Laura (April 28, 2008). ["'Broken Heart' Image the Last for NASA's Long-Lived Polar Mission"](https://web.archive.org/web/20170624133838/https://www.nasa.gov/topics/earth/features/polar_heart.html). NASA. Archived from [the original](https://www.nasa.gov/topics/earth/features/polar_heart.html) on June 24, 2017. Retrieved August 19, 2018.

1. **[^](#cite_ref-heavens-above_4-0)** ["Polar - Orbit"](https://heavens-above.com/orbit.aspx?satid=23802). *[Heavens-Above](/source/Heavens-Above)*. August 19, 2018. Retrieved August 19, 2018.

1. **[^](#cite_ref-5)** Nelson, Buddy (April 30, 2008). ["Long-Lived NASA Polar Satellite, Built by Lockheed Martin, Ends Service After 12 Productive Years"](https://web.archive.org/web/20090104024248/http://www.lockheedmartin.com/news/press_releases/2008/4-30-polarsat.html). Lockheed Martin. Archived from [the original](http://www.lockheedmartin.com/news/press_releases/2008/4-30-polarsat.html) on January 4, 2009.

## External links

Wikimedia Commons has media related to [Polar (satellite)](https://commons.wikimedia.org/wiki/Category:Polar_(satellite)).

- [Spaceflight portal](https://en.wikipedia.org/wiki/Portal:Spaceflight)

- [*Polar* website](https://pwg.gsfc.nasa.gov/polar/) at NASA.gov

- [Old *Polar* website](https://www-istp.gsfc.nasa.gov/istp/polar/) at NASA.gov

v t e ← 1995 Orbital launches in 1996 1997 → January STS-72 (SPARTAN-206) PAS-3R, MEASAT-1 Koreasat 2 Kosmos 2327 Gorizont #43L February Palapa C1 N-STAR b Intelsat 708 NEAR Shoemaker Kosmos 2328, Kosmos 2329, Kosmos 2330, Gonets-D1 #1, Gonets-D1 #2, Gonets-D1 #3 Gran' #44L Soyuz TM-23 STS-75 (TSS-1R) Polar March REX II Intelsat 707 Kosmos 2331 IRS-P3 STS-76 USA-117 April Inmarsat-3 F1 Astra 1F MSAT-1 Priroda MSX Kosmos 2332 USA-118 BeppoSAX May Progress M-31 USA-119, USA-120, USA-121, USA-122, USA-123, USA-124 Kometa #18 Palapa C2, Amos-1 MSTI-3 STS-77 (SPARTAN-207, IAE, PAMS-STU) Galaxy 9 Gorizont #44L June Cluster F1, Cluster F2, Cluster F3, Cluster F4 Intelsat 709 STS-78 Kobal't July TOMS-EP USA-125 Apstar 1A Arabsat 2A, Türksat 1C USA-126 USA-127 Progress M-32 August Télécom 2D, Italsat 2 Molniya 1-79 Midori, Fuji 2 Soyuz TM-24 Chinasat-7 FAST Interbol 2, Magion 5, Victor September Kosmos 2333 Kosmos 2334, UNAMSAT-2 Inmarsat-3 F2 GE-1 EchoStar II USA-128 STS-79 Ekspress-6 October FSW-17 Molniya 3-62 November HETE, SAC-B Mars Global Surveyor Arabsat 2B, MEASAT-2 Mars 96 STS-80 (WSF, ORFEUS-SPAS) Progress M-33 Hot Bird 2 December Mars Pathfinder (Sojourner) Kosmos 2335 Inmarsat-3 F3 Kosmos 2336 USA-129 Bion No.11 Launches are separated by dots ( • ), payloads by commas ( , ), multiple names for the same satellite by slashes ( / ). Crewed flights are underlined. Launch failures are marked with the † sign. Payloads deployed from other spacecraft are (enclosed in parentheses).

v t e Magnetospherics Submagnetosphere Atmospheric circulation Aurora Earth's magnetic field Geosphere Jet stream Polar wind Earth's magnetosphere Birkeland current Bow shock Ionosphere Magnetopause Magnetosheath Magnetosphere Magnetosphere chronology Magnetosphere particle motion Plasmasphere Ring current Van Allen radiation belt Solar wind Magnetic cloud Coronal mass ejection Solar flare Geomagnetic storm Heliosphere Interplanetary magnetic field Heliospheric current sheet Heliopause Solar particle event Space climate Space weather Satellites Arase (2016) Cluster II Double Star Geotail IMAGE MMS (2015) Polar THEMIS Van Allen Probes Wind Research projects EISCAT HAARP SHARE Unwin Radar SuperDARN Sura Ionospheric Heating Facility Other magnetospheres Hermian Venusian Lunar Martian Jovian Ganymedian Saturnian Uranian Neptunian Related topics Flux tube Gas torus Lunar swirls Ring systems Jupiter Saturn Uranus Neptune

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Adapted from the Wikipedia article [Polar (satellite)](https://en.wikipedia.org/wiki/Polar_(satellite)) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Polar_(satellite)?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.