Explorer program
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- This article is about the space exploration program. "Explorer program" may also refer to the file browser of Windows, called Windows Explorer.
The Explorer program was the United States's first successful attempt to launch an artificial satellite . It began as a U.S. Army proposal to place a scientific satellite into orbit during the International Geophysical Year. That proposal was rejected in favor of the U.S. Navy's Project Vanguard. It was revived as a crash program to catch up with the Soviet Union after that nation's launch of Sputnik I on October 4, 1957. (See: Sputnik crisis) Explorer 1 was launched January 31, 1958. Besides being the first U.S. satellite, it is known for discovering the Van Allen radiation belt.
[edit] Explorer at NASA
The Explorer program was taken over by NASA, which continued to use the name for unmanned space missions. Over the years, NASA has launched a series of "Explorer" spacecraft carrying a wide variety of scientific investigations. The list below identifies the 79 successful missions as of December 2004. As of this writing, Explorers 50 (IMP-8), 68-71, 73-74 and 77, 79-83 (SAMPEX, RXTE, FAST, ACE, TRACE, SWAS, FUSE, WMAP, RHESSI, CHIPSat, GALEX and SWIFT) are still operating.
NASA's Explorer spacecraft series not only is the longest running series of spacecraft, it has produced highly-durable, well-engineered spacecraft as well. Of the 79 successful Explorer missions depicted, fully five of them had had missions which lasted 10 or more years, the longest of which (IMP-8) has been operational for over 26 years now and still produces valuable information about the solar wind. NASA's IUE spacecraft operated for 19 years and produced copious amounts of data for the astronomical community. The ISEE 3/ICE spacecraft operated for 14 years. As of March of 2000, of the ten operational Explorer missions, SNOE and TRACE have operated for about two years, ACE two and a half years, FAST for about three and a half, RXTE for over four, EUVE and SAMPEX for nearly eight, and IMP 8 for more than 26. SWAS has been operational for slightly more than one year, having been launched in early December 1998.
[edit] Mission History
| Explorer | Name | Launch Date | Mission |
|---|---|---|---|
| 1 | Explorer 1 | January 31, 1958 | Energy particles studies, discovered the Van Allen radiation belt |
| 2 | Explorer 2 | March 5, 1958 | Failed to achieve orbit |
| 3 | Explorer 3 | March 26, 1958 | Energy particles studies |
| 4 | Explorer 4 | July 26, 1958 | Energy particles studies |
| 5 | Explorer 5 | August 24, 1958 | Failed to achieve orbit |
| -- | S-1 | July 16, 1959 | Failed to achieve orbit |
| 6 | S-2 | August 7, 1959 | Magnetosphere research |
| 7 | S-1a | October 13, 1959 | Energy particles studies |
| -- | S-46 | March 23, 1960 | Failed to achieve orbit |
| 8 | S-56 | November 3, 1960 | Measured atmospheric composition of the ionosphere |
| -- | S-56 | December 4, 1960 | Failed to achieve orbit |
| 9 | S-56a | February 16, 1961 | Atmospheric density measurements |
| -- | S-45 | February 24, 1961 | Failed to achieve orbit |
| 10 | P-14 | March 25, 1961 | Investigated field magnetic field between the earth |
| 11 | S-15 | April 27, 1961 | Gamma ray astronomy |
| -- | S-45a | May 25, 1961 | Failed to achieve orbit |
| -- | S-55 | June 30, 1961 | Failed to achieve orbit |
| 12 | EPE A | August 16, 1961 | Energetic particles research |
| 13 | S-55a | August 25, 1961 | Micrometeoroids research |
| 14 | EPE B | October 2, 1962 | Energetic particles research |
| 15 | EPE C | October 27, 1962 | Energetic particles research |
| 16 | S-55b | December 16, 1962 | Micrometeoroids research |
| 17 | AE A | April 3, 1963 | Atmospheric research |
| 18 | IMP A | November 27, 1963 | Magnetospheric research |
| 19 | AD A | December 19, 1963 | Atmospheric density measurements |
| 20 | IE A | August 25, 1964 | Ionosphere research |
| 21 | IMP B | October 4, 1964 | Magnetospheric research |
| 22 | BE B | October 10, 1964 | Ionospheric and geodetic research |
| 23 | Explorer 23 | November 6, 1964 | Micrometeoric research |
| 24 | AD B | November 21, 1964 | Atmospheric density measurements |
| 25 | Injun 4 (IE B) | November 21, 1964 | Ionospheric research |
| 26 | EPE D | December 21, 1964 | High energy particle observations |
| 27 | IMP C | April 29, 1965 | Magnetospheric research |
| 28 | IMP C | May 29, 1965 | Magnetospheric research |
| 29 | GEOS A | November 6, 1965 | Geodetic earth monitoring |
| 30 | Solrad 8 (SE A) | November 19, 1965 | Solar radiation monitoring |
| 31 | DME A | November 29, 1965 | Ionospheric research |
| 32 | AE B | May 25, 1966 | Atmospheric research |
| 33 | IMP D | July 1, 1966 | Magnetospheric research |
| 34 | IMP F | May 24, 1967 | Magnetospheric research |
| 35 | IMP E | July 19, 1967 | Magnetospheric research |
| 36 | GEOS B | January 11, 1968 | Geodetic earth monitoring |
| 37 | Solrad 9 (SE B) | March 5, 1968 | Solar radiation monitoring |
| 38 | RAE A | July 4, 1968 | Radio astronomy |
| 39 | AD C | August 8, 1968 | Atmospheric density measurements |
| 40 | Injun 5 (IE C) | August 8, 1968 | Magnetospheric Research |
| 41 | IMP G | June 21, 1969 | Magnetospheric research |
| 42 | SAS A | December 12, 1970 | X-Ray Astronomy |
| 43 | IMP H | March 13, 1971 | Magnetospheric research |
| 44 | Solrad 10 (SE C) | July 8, 1971 | Solar radiation monitoring |
| 45 | SSS A | November 15, 1971 | Magnetospheric research |
| 46 | MTS A | August 13, 1972 | Micrometeoroids research |
| 47 | IMP I | September 23, 1972 | Magnetospheric research |
| 48 | SAS B | November 15, 1972 | X-Ray Astronomy |
| 49 | RAE B | June 10, 1973 | Radio astronomy |
| 50 | IMP J | October 26, 1973 | Magnetospheric research |
| 51 | AE C | December 16, 1973 | Atmospheric research |
| 52 | Hawkeye 1, Injun 6 (IE D) | June 3, 1974 | Magnetospheric research |
| 53 | SAS C | May 7, 1975 | X-Ray Astronomy |
| 54 | AE D | October 6, 1975 | Atmospheric research |
| 55 | AE E | November 20, 1975 | Atmospheric research |
| 56 | ISEE 1 | October 22, 1977 | Magnetospheric research |
| 57 | IUE | January 26, 1978 | Ultraviolet astronomy |
| 58 | HCMM | April 26, 1978 | Thermal mapping of the earth |
| 59 | ISEE 3 (ICE) | August 12, 1978 | Magnetospheric research |
| 60 | SAGE | February 18, 1979 | Stratospheric aerosol and ozone data |
| 61 | Magsat | October 30, 1979 | Mapped the near surface magnetic field of the Earth |
| 62 | DE 1 | August 3, 1981 | Magnetospheric research |
| 63 | DE 2 | August 3, 1981 | Magnetospheric research |
| 64 | SME | October 6, 1981 | Atmospheric research |
| 65 | CCE | August 16, 1984 | Magnetospheric research |
| 66 | COBE | November 18, 1989 | Microwave astronomy |
| 67 | EUVE | June 7, 1992 | Ultraviolet astronomy |
| 68 | SAMPEX | July 3, 1992 | Magnetospheric research |
| 69 | RXTE | December 30, 1995 | X-ray astronomy |
| 70 | FAST | August 21, 1996 | Auroral phenomena |
| 71 | ACE | August 25, 1997 | Solar/interplanetary/interstellar particle research |
| 72 | SNOE | February 26, 1998 | Atmospheric research |
| 73 | TRACE | April 2, 1998 | Solar observatory |
| 74 | SWAS | December 6, 1998 | Submillimeter astronomy |
| 75 | WIRE | March 5, 1999 | InfraRed astronomy, primary mission failed due to loss of coolant |
| 76 | TERRIERS | May 18, 1999 | Atmospheric research, satellite failed shortly after achieving orbit |
| 77 | FUSE | June 23, 1999 | Ultraviolet astronomy |
| 78 | IMAGE | March 25, 2000 | Magnetospheric research |
| 79 | WMAP | June 30, 2001 | Microwave astronomy |
| 80 | RHESSI | February 5, 2002 | X-ray and gamma ray solar flare imaging |
| 81 | CHIPSat | January 13, 2003 | Ultraviolet spectroscopy and astronomy |
| 82 | GALEX | April 28, 2003 | Ultraviolet astronomy |
| 83 | SWIFT | November 20, 2004 | Gamma ray astronomy |
