Encyclopedia Astronautica
Small Explorer


A series of relatively low-cost satellites launched by NASA for solar and astronomical studies.

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Associated Countries
Associated Spacecraft
  • SAMPEX American earth magnetosphere satellite. One launch, 1992.07.03. More...
  • FAST American earth magnetosphere satellite. One launch, 1996.08.21. FAST was designed to observe and measure rapidly varying electric and magnetic fields and the flow of electrons and ions above the aurora. More...
  • TRACE American solar satellite. One launch, 1998.04.02. TRACE, carried a 30-cm extreme ultraviolet imaging telescope for studies of the sun. Lockheed was the lead contractor while the Smithsonian Astrophysical Observatory made the telescope mirrors. More...
  • SWAS American infrared astronomy satellite. One launch, 1998.12.06. SWAS, the Submillimeter Wave Astronomy Satellite, had a 0.6m telescope with a 490 to 550 GHz submillimeter receiver and an acousto-optical spectrometer. More...

Associated Launch Vehicles
  • Scout G American all-solid orbital launch vehicle. Four stage vehicle consisting of 1 x Algol 3A + 1 x Castor 2 + 1 x Antares 3 + 1 x Star 20 More...
  • Pegasus XL American air-launched orbital launch vehicle. Uprated version of Pegasus air-launched winged light satellite launcher. 4 stage vehicle consisting of 1 x L-1011 + 1 x Pegasus XL stage 1 + 1 x Orion 50XL + 1 x Orion 38. More...

Associated Manufacturers and Agencies
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...
  • Point Arguello WADZ Air-launched rocket drop zone known to have been used for 28 launches from 1990 to 2007, reaching up to 4539 kilometers altitude. More...

Small Explorer Chronology


1992 July 3 - . 14:19 GMT - . Launch Site: Vandenberg. Launch Complex: Vandenberg SLC5. LV Family: Scout. Launch Vehicle: Scout G. LV Configuration: Scout G-1 S215C.
  • SAMPEX - . Mass: 158 kg (348 lb). Nation: USA. Agency: NASA Greenbelt. Program: Small Explorer. Class: Earth. Type: Magnetosphere satellite. Spacecraft: SAMPEX. USAF Sat Cat: 22012 . COSPAR: 1992-038A. Apogee: 670 km (410 mi). Perigee: 506 km (314 mi). Inclination: 81.7000 deg. Period: 96.50 min. Summary: First Small Explorer mission; Solar Anomalous and Magnetospheric Particle Explorer. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B)..

1996 August 21 - . 09:47 GMT - . Launch Site: Point Arguello WADZ. Launch Pad: 36.0 N x 123.0 W. Launch Platform: L-1011. LV Family: Pegasus. Launch Vehicle: Pegasus XL. LV Configuration: Pegasus XL F13.
  • FAST - . Nation: USA. Agency: NASA Greenbelt. Program: Small Explorer. Class: Earth. Type: Magnetosphere satellite. Spacecraft: FAST. USAF Sat Cat: 24285 . COSPAR: 1996-049A. Apogee: 4,163 km (2,586 mi). Perigee: 353 km (219 mi). Inclination: 83.0000 deg. Period: 132.70 min. Summary: Second Small Explorer mission..

1998 April 2 - . 02:42 GMT - . Launch Site: Point Arguello WADZ. Launch Pad: 36.0 N x 123.0 W. Launch Platform: L-1011. LV Family: Pegasus. Launch Vehicle: Pegasus XL. LV Configuration: Pegasus XL F21.
  • TRACE - . Nation: USA. Agency: NASA Greenbelt. Program: Small Explorer. Class: Astronomy. Type: Solar astronomy satellite. Spacecraft: TRACE. USAF Sat Cat: 25280 . COSPAR: 1998-020A. Apogee: 652 km (405 mi). Perigee: 602 km (374 mi). Inclination: 97.8000 deg. Period: 97.10 min. NASA's third Small Explorer, the Transition Region and Coronal Explorer (TRACE), was successfully launched by an Orbital Pegasus XL. The L-1011 carrier aircraft took off from Vandenberg and dropped the Pegasus over the Pacific Ocean. TRACE, a project led by Lockheed's solar physics group, carried a 30-cm extreme ultraviolet imaging telescope which will study the Sun. The telescope mirrors were made by the Smithsonian Astrophysical Observatory. TRACE had an 8.5 arcmin field of view and 1 arcsecond resolution.

1998 December 6 - . 00:57 GMT - . Launch Site: Point Arguello WADZ. Launch Pad: 36.0 N x 123.0 W. Launch Platform: L-1011. LV Family: Pegasus. Launch Vehicle: Pegasus XL. LV Configuration: Pegasus XL F25.
  • SWAS - . Nation: USA. Agency: NASA Greenbelt. Program: Small Explorer. Class: Astronomy. Type: X-ray astronomy satellite. Spacecraft: SWAS. USAF Sat Cat: 25560 . COSPAR: 1998-071A. Apogee: 611 km (379 mi). Perigee: 599 km (372 mi). Inclination: 69.9000 deg. Period: 96.80 min. On December 3 the Orbital Sciences L-1011 Stargazer took off from Vandenberg AFB Runway 30/12 carrying a Pegasus XL launch vehicle with the SWAS satellite aboard. It reached the drop box at 36.0N 123.0W over the Pacific, but due to a software-related problem the range ordered the launch scrubbed and the L-1011 returned to base. After a further delay due to weather, the L-1011 took off at 23:58 GMT on December 5 and SWAS reached orbit and separated from the third stage at 01:09 GMT. SWAS, the Sub-millimetre Wave Astronomy Satellite, had a 0.6m telescope with a 490 to 550 GHz sub-millimetre receiver and an acousto-optical spectrometer. SWAS was used to study the cooling of molecular cloud cores, the sites of star formation in our galaxy, by measuring lines from molecular oxygen and water.

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