Encyclopedia Astronautica
Themis



wthemis.jpg
Themis
Credit: NASA
American earth magnetosphere satellite. 5 launched, 2007.02.17.

The five Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites were part of a combined ground- and space- based system designed to determine what physical process in near-Earth space initiate the violent eruptions of the aurora that occur during substorms in the Earth's magnetosphere.

The THEMIS satellites would conduct a two-year mission in conjunction with the ground-based elements. The THEMIS probes would line up over North America once every four days. Over the mission's two-year lifetime, the probes were expected to observe some 30 substorms.

THEMIS was the fifth medium-class mission under NASA's Explorer Program, managed by the Goddard Space Flight Center, Greenbelt, Maryland. The University of California at Berkeley's Space Sciences Laboratory and Swales Aerospace, Beltsville, Maryland., built the THEMIS satellites.

The Themis instruments included:

  • Space Based
    • Instrument Data Processing Unit (IDPU), which housed most of the electronics for the instruments on the THEMIS spacecraft. e
    • Electric Field Instruments (EFI), designed and built to sense the electric field in Earth's magnetosphere + Read More
    • Flux Gate Magnetometer (FGM), to measure the background magnetic field in order to identify and time the abrupt reconfigurations of the magnetosphere during substorm onset.
    • Search Coil Magnetometers (SCM), to measure low frequency magnetic field fluctuations and waves in three directions in Earth's magnetosphere.
    • Electrostatic Analyzer (ESA), to measure thermal electrons and ions in order to identify and track high-speed flows through the magneto tail and identify pressure pulses.
    • Solid State Telescope (SST), to measure particle distribution functions
  • Ground-Based
    • Ground-Based All-Sky Imager (ASI) Array to observe the aurora over the Northern American continent from Canada to Alaska in order to determine where and when the auroral substorm onset occurs.
    • Ground-Based Magnetometer (GMAG) Array, to measure changes in the Earth's magnetic field near Earth's surface due to substorm onset in order to help determine the timing of substorm events.

Characteristics

Cost Notes: Total mission cost $200 million, incl 5 sats, lv. Spacecraft delta v: 940 m/s (3,080 ft/sec). Electric System: 0.0400 average kW.

Gross mass: 126 kg (277 lb).
Unfuelled mass: 77 kg (169 lb).
Payload: 26 kg (57 lb).
Specific impulse: 200 s.
First Launch: 2007.02.17.
Number: 5 .

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 7925 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 More...

Associated Manufacturers and Agencies
  • Swales American manufacturer of spacecraft. Swales Aerospace, USA. More...

Associated Propellants
  • Hydrazine Hydrazine (N2H4) found early use as a fuel, but it was quickly replaced by UDMH. It is still used as a monopropellant for satellite station-keeping motors. Hydrazine (N2H4) found early use as a fuel, but it was quickly replaced by UDMH. It is still used as a monopropellant for satellite station-keeping motors. More...

Associated Launch Sites
  • Cape Canaveral America's largest launch center, used for all manned launches. Today only six of the 40 launch complexes built here remain in use. Located at or near Cape Canaveral are the Kennedy Space Center on Merritt Island, used by NASA for Saturn V and Space Shuttle launches; Patrick AFB on Cape Canaveral itself, operated the US Department of Defense and handling most other launches; the commercial Spaceport Florida; the air-launched launch vehicle and missile Drop Zone off Mayport, Florida, located at 29.00 N 79.00 W, and an offshore submarine-launched ballistic missile launch area. All of these take advantage of the extensive down-range tracking facilities that once extended from the Cape, through the Caribbean, South Atlantic, and to South Africa and the Indian Ocean. More...
  • Cape Canaveral LC17B Delta launch complex. Part of a dual launch pad complex built for the Thor ballistic missile program in 1956. Upgraded over the decades for use with Thor, Delta, Delta II, and Delta III launch vehicles, it remained in use for over half a century. More...

Themis Chronology


2007 February 17 - . 23:01 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC17B. Launch Pad: SLC17B. LV Family: Delta. Launch Vehicle: Delta 7925. LV Configuration: Delta 7925-10C D323.
  • Themis P1 - . Payload: Themis A. Mass: 125 kg (275 lb). Nation: USA. Agency: NASA. Manufacturer: Swales. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Themis. USAF Sat Cat: 30580 . COSPAR: 2007-004A. Apogee: 87,254 km (54,217 mi). Perigee: 1,003 km (623 mi). Inclination: 14.1000 deg. Period: 1,882.70 min. The five simultaneously-launched Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites were the fifth medium-class mission under NASA's Explorer Program. They formed part of a combined ground- and space- based system designed to determine what physical process in near-Earth space initiate the violent eruptions of the aurora that occur during substorms in the Earth's magnetosphere.
  • Themis P2 - . Payload: Themis B. Mass: 125 kg (275 lb). Nation: USA. Agency: NASA. Manufacturer: Swales. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Themis. USAF Sat Cat: 30581 . COSPAR: 2007-004B. Apogee: 87,114 km (54,130 mi). Perigee: 1,004 km (623 mi). Inclination: 14.1000 deg. Period: 1,878.80 min.
  • Themis P3 - . Payload: Themis C. Mass: 125 kg (275 lb). Nation: USA. Agency: NASA. Manufacturer: Swales. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Themis. USAF Sat Cat: 30582 . COSPAR: 2007-004C. Apogee: 87,792 km (54,551 mi). Perigee: 736 km (457 mi). Inclination: 14.2000 deg. Period: 1,890.30 min.
  • Themis P4 - . Mass: 125 kg (275 lb). Nation: USA. Agency: NASA. Manufacturer: Swales. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Themis. USAF Sat Cat: 30797 . COSPAR: 2007-004D. Apogee: 67,517 km (41,953 mi). Perigee: 4,048 km (2,515 mi). Inclination: 4.6000 deg. Period: 1,435.90 min.
  • Themis P5 - . Mass: 125 kg (275 lb). Nation: USA. Agency: NASA. Manufacturer: Swales. Class: Earth. Type: Magnetosphere satellite. Spacecraft: Themis. USAF Sat Cat: 30798 . COSPAR: 2007-004E. Apogee: 67,523 km (41,956 mi). Perigee: 4,045 km (2,513 mi). Inclination: 5.1000 deg. Period: 1,436.00 min.

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