Encyclopedia Astronautica

American earth magnetosphere satellite. One launch, 1996.02.24. Polar was designed to measure the entry, energization, and transport of plasma into the magnetosphere as part of the International Solar Terrestrial Program (ISTP).

Polar, and its sister spacecraft Wind, were NASA's contribution to the International Solar Terrestrial Program (ISTP), an international effort to quantify the effects of solar energy on the Earth's magnetic field. The Polar mission's specific objectives were to (1) investigate energy input to the ionospheric region through the day side cusp; (2) determine the mechanisms of ionospheric plasma outflow; (3) study the characteristics of the auroral plasma acceleration regions; (4) provide global, multispectral auroral images of the footprint of magnetospheric energy disposition into the ionosphere and upper atmosphere; (5) help determine the role of the ionosphere in sun storm phenomena and the overall magnetospheric energy balance; and (6) document ions leaving the atmosphere and subsequently appearing in the solar wind, or electrons of solar wind origin precipitating to auroral altitudes.

Data from Polar would be correlated with data from ground-based scientific observatories and the other spacecraft in the ISTP program (Wind, Geotail and SOHO (the Cluster spacecraft would also have participated, but were destroyed during launch)) to better understand the physical effects of solar activity on interplanetary space and the Earth's space environment.

The spacecraft was cylindrical with body mounted solar arrays, and spin stabilized at 10 rpm. Two pairs of wire booms for the Plasma Wave Instrument (PWI) experiment protuded from the body, as well as one belt antenna and four low-gain antennas.

The payload included:

  • Plasma Wave Investigation (PWI) - designed to provide comprehensive measurements of plasma wave phenomena in the high latitude auroral zones, day side magnetic cusp regions, plasmasphere and plasma sheet.
  • Fast Plasma Analyzer (HYDRA) - measured the rapid very low energy of the 3-dimensional ion and electron distribution function.
  • Magnetic Fields Experiment - a magnetometer designed to measure the magnetic fields in the high and low altitude polar magnetosphere. This experiment would investigate the behavior of field-aligned current systems and the role they play in the acceleration of particles and the dynamics of the fields in the polar cusp, magnetosphere, and magneto-sheath.
  • Toroidal Imaging Mass-Angle Spectrograph (TIMAS) - measured the 3-dimensional velocity distribution functions of all major magnetospheric ion species.
  • Electric Field Instrument (EFI) - measured the three components of the ambient vector electric field and the thermal electron density.
  • Thermal Ion Dynamics Experiment (TIDE) and Plasma Source Instrument (PSI) - would track the outflow of ionospheric plasma throughout the magnetosphere.
  • Ultraviolet Imager (UVI) - a two dimensional imager sensitive to far ultraviolet wavelengths with an 8 deg. circular FOV. The instrument would conduct observations of both the sunlit and nightside polar regions in the far ultraviolet wavelengths to help quantify the overall effects of solar energy input to the earth's polar regions.
  • Visible Imaging System (VIS) - a set of three low-light-level cameras designed to provide images of the aurora.
  • Polar Ionospheric X-ray Imaging Experiment (PIXIE) - would measure the spatial distribution and temporal variation of x-ray emissions in the energy range 3 to 60 keV from the earth's atmosphere.
  • Charge and Mass Magnetospheric Ion Composition Experiment (CAMMICE) - would determine the composition of the energetic particle populations of the Earth's magnetosphere to identify how these charged particles were energized and transported from their source to the magnetosphere.
  • Comprehensive Energetic Particle Pitch Angle Distribution
Total cost of the project was $ 238 million, and it launched 2.5 years late to original schedule.

Gross mass: 1,300 kg (2,800 lb).
Height: 1.85 m (6.06 ft).
First Launch: 1996.02.24.
Number: 1 .

More... - Chronology...

Associated Countries
See also
  • Delta The Delta launch vehicle was America's longest-lived, most reliable, and lowest-cost space launch vehicle. Development began in 1955 and it continued in service in the 21st Century despite numerous candidate replacements. More...

Associated Launch Vehicles
  • Delta American orbital launch vehicle. The Delta launch vehicle was America's longest-lived, most reliable, and lowest-cost space launch vehicle. Delta began as Thor, a crash December 1955 program to produce an intermediate range ballistic missile using existing components, which flew thirteen months after go-ahead. Fifteen months after that, a space launch version flew, using an existing upper stage. The addition of solid rocket boosters allowed the Thor core and Able/Delta upper stages to be stretched. Costs were kept down by using first and second-stage rocket engines surplus to the Apollo program in the 1970's. Continuous introduction of new 'existing' technology over the years resulted in an incredible evolution - the payload into a geosynchronous transfer orbit increasing from 68 kg in 1962 to 3810 kg by 2002. Delta survived innumerable attempts to kill the program and replace it with 'more rationale' alternatives. By 2008 nearly 1,000 boosters had flown over a fifty-year career, and cancellation was again announced. More...
  • Delta 2 7000 American orbital launch vehicle. The Delta 7000 series used GEM-40 strap-ons with the Extra Extended Long Tank core, further upgraded with the RS-27A engine. More...
  • Delta 7925-10 American orbital launch vehicle. Four stage vehicle consisting of 9 x GEM-40 + 1 x EELT Thor/RS-27A + 1 x Delta K + 1 x Star 48B with 3.05 m (10 foot) diameter fairing More...

Associated Manufacturers and Agencies
  • NASA American agency overseeing development of rockets and spacecraft. National Aeronautics and Space Administration, USA, USA. More...
  • Lockheed American manufacturer of rockets, spacecraft, and rocket engines. Lockheed Martin, Sunnyvale, CA, USA. More...

  • McDowell, Jonathan, Jonathan's Space Home Page (launch records), Harvard University, 1997-present. Web Address when accessed: here.
  • McDowell, Jonathan, Jonathan's Space Report (Internet Newsletter), Harvard University, Weekly, 1989 to Present. Web Address when accessed: here.
  • JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. Web Address when accessed: here.

Associated Launch Sites
  • Vandenberg Vandenberg Air Force Base is located on the Central Coast of California about 240 km northwest of Los Angeles. It is used for launches of unmanned government and commercial satellites into polar orbit and intercontinental ballistic missile test launches toward the Kwajalein Atoll. More...
  • Vandenberg SLC2W Delta launch complex. Originally a Thor 75 SMS launch pad. Upgraded to a space launch complex in 1966. More...

Polar Chronology

1996 February 24 - . 11:24 GMT - . Launch Site: Vandenberg. Launch Complex: Vandenberg SLC2W. LV Family: Delta. Launch Vehicle: Delta 7925-10. LV Configuration: Delta 7925-10 D233.
  • Polar - . Mass: 1,300 kg (2,800 lb). Nation: USA. Agency: NASA Greenbelt. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Polar. USAF Sat Cat: 23802 . COSPAR: 1996-013A. Apogee: 50,423 km (31,331 mi). Perigee: 5,554 km (3,451 mi). Inclination: 86.3000 deg. Period: 1,070.20 min. Summary: HEO. Fields and particles, auroral studies; part of International Solar Terrestrial Physics program..

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