Explorer program

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For other uses, see Explorer (disambiguation).

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 1 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.

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[edit] Explorer at NASA

ISEE-C in a dynamic test chamber, 1978
ISEE-C in a dynamic test chamber, 1978

The Explorer program was taken over by NASA, which continued to use the name for robotic spacecraft 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, 79-83 (SAMPEX, RXTE, FAST, ACE, TRACE, SWAS, 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.

Energetic Particle Explorers

Explorers 12, 14, 15 and 26 were the S 3 series of spacecraft, known as Energetic Particle Explorers. They were spin-stabilized, solar-cell-powered spacecraft instrumented to measure cosmic ray particles, trapped particles, solar wind protons, and magnetospheric and interplanetary magnetic fields.[1]

[edit] Mission History

Explorer Missions
Explorer Name Launch Date Mission End of Data Re-Entry
1 Explorer 1 January 31, 1958 Energy particles studies, discovered the Van Allen radiation belt May 23, 1958 March 31, 1970
2 Explorer 2 March 5, 1958 Failed to achieve orbit - -
3 Explorer 3 March 26, 1958 Energy particles studies June 27, 1958 June 27 1958
4 Explorer 4 July 26, 1958 Energy particles studies October 5, 1958 October 23, 1959
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 October 6, 1959 July 1, 1961
7 S-1a October 13, 1959 Energy particles studies August 24, 1961 In orbit
-- S-46 March 23, 1960 Failed to achieve orbit - -
8 S-56 November 3, 1960 Measured atmospheric composition of the ionosphere  ? in orbit
-- S-56 December 4, 1960 Failed to achieve orbit - -
9 S-56a February 16, 1961 Atmospheric density measurements  ? April 9, 1964
-- S-45 February 24, 1961 Failed to achieve orbit - -
10 P-14 March 25, 1961 Investigated field magnetic field between the earth  ? June 1, 1968
11 S-15 April 27, 1961 Gamma ray astronomy  ? In orbit
-- 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  ? September 1, 1963
13 S-55a August 25, 1961 Micrometeoroids research  ? In orbit
14 EPE B October 2, 1962 Energetic particles research  ? July 1, 1966
15 EPE C October 27, 1962 Energetic particles research  ? January 15, 1978
16 S-55b December 16, 1962 Micrometeoroids research ? November 24, 1966?
17 AE A April 3, 1963 Atmospheric research July 10, 1963 November 24, 1966?
18 IMP A November 27, 1963 Magnetospheric research ? December 30, 1965
19 AD A December 19, 1963 Atmospheric density measurements ? May 10, 1981
20 IE A August 25, 1964 Ionosphere research ? In orbit
21 IMP B October 4, 1964 Magnetospheric research ? January 30, 1966
22 BE B (S-66) October 10, 1964 Ionospheric and geodetic research ? In orbit
23 Explorer 23 (S-55c) November 6, 1964 Micrometeoric research ? June 29, 1983
24 AD B November 21, 1964 Atmospheric density measurements ? October 18, 1968
25 Injun 4 (IE B) November 21, 1964 Ionospheric research ? In orbit
26 EPE D December 21, 1964 High energy particle observations ? In orbit
27 IMP C April 29, 1965 Magnetospheric research ? In orbit
28 IMP C May 29, 1965 Magnetospheric research ? July 4, 1968
29 GEOS A November 6, 1965 Geodetic earth monitoring ? In orbit
30 Solrad 8 (SE A) November 19, 1965 Solar radiation monitoring
(Cover for covert ELINT mission)		 ? In orbit
31 DME A November 29, 1965 Ionospheric research ? In orbit
32 AE B May 25, 1966 Atmospheric research March 1967 February 22, 1985
33 IMP D July 1, 1966 Magnetospheric research ? In orbit
34 IMP F May 24, 1967 Magnetospheric research ? May 3, 1969
35 IMP E July 19, 1967 Magnetospheric research June 24, 1973 ?
36 GEOS B January 11, 1968 Geodetic earth monitoring ? In orbit
37 Solrad 9 (SE B) March 5, 1968 Solar radiation monitoring
(Cover for covert ELINT mission)		 ? November 16, 1990
38 RAE A July 4, 1968 Radio astronomy ? In orbit
39 AD C August 8, 1968 Atmospheric density measurements ? June 22, 1981
40 Injun 5 (IE C) August 8, 1968 Magnetospheric Research ? In orbit
41 IMP G June 21, 1969 Magnetospheric research ? December 23, 1972
42 SAS A December 12, 1970 X-Ray Astronomy March 1973 April 5, 1979
43 IMP H March 13, 1971 Magnetospheric research ? October 2, 1974
44 Solrad 10 (SE C) July 8, 1971 Solar radiation monitoring
(Cover for covert ELINT mission)		 ? December 15, 1979
45 SSS A November 15, 1971 Magnetospheric research ? January 10, 1992
46 MTS A August 13, 1972 Micrometeoroids research ? November 2, 1979
47 IMP I September 23, 1972 Magnetospheric research ? In orbit
48 SAS B November 15, 1972 X-Ray Astronomy ? August 20, 1980
49 RAE B June 10, 1973 Radio astronomy ? In Lunar orbit
50 IMP J October 26, 1973 Magnetospheric research Operational (34 years) In orbit
51 AE C December 16, 1973 Atmospheric research ? December 12, 1978
52 Hawkeye 1, Injun 6 (IE D) June 3, 1974 Magnetospheric research April 28, 1978 April 28, 1978
53 SAS C May 7, 1975 X-Ray Astronomy ? April 9, 1979
54 AE D October 6, 1975 Atmospheric research ? March 12, 1976
55 AE E November 20, 1975 Atmospheric research ? January 10, 1981
56 ISEE 1 October 22, 1977 Magnetospheric research ? September 26, 1987
57 IUE January 26, 1978 Ultraviolet astronomy September 30, 1996 In orbit
58 HCMM April 26, 1978 Thermal mapping of the earth ? ?
59 ISEE 3 (ICE) August 12, 1978 Magnetospheric research May 5, 1997 In heliocentric orbit
60 SAGE February 18, 1979 Stratospheric aerosol and ozone data ? April 11, 1989
61 Magsat October 30, 1979 Mapped the near surface magnetic field of the Earth ? June 11, 1980
62 DE 1 August 3, 1981 Magnetospheric research ? ?
63 DE 2 August 3, 1981 Magnetospheric research ? ?
64 SME October 6, 1981 Atmospheric research April 4, 1989 March 5, 1991
65 CCE August 16, 1984 Magnetospheric research ? ?
66 COBE November 18, 1989 Microwave astronomy operational? In orbit
67 EUVE June 7, 1992 Ultraviolet astronomy January 30, 2002 In orbit
68 SAMPEX July 3, 1992 Magnetospheric research operational? In orbit
69 RXTE December 30, 1995 X-ray astronomy Operational (11 years) In orbit
70 FAST August 21, 1996 Auroral phenomena operational? In orbit
71 ACE August 25, 1997 Solar/interplanetary/interstellar particle research Operational (11 years) In Lissajous orbit
72 SNOE February 26, 1998 Atmospheric research December 13, 2003 December 13, 2003
73 TRACE April 2, 1998 Solar observatory Operational (9 years) In orbit
74 SWAS December 6, 1998 Submillimeter astronomy July 2004 hibernation
August 2005 after Deep Impact sub-mission		 In orbit
75 WIRE March 5, 1999 InfraRed astronomy, primary mission failed due to loss of coolant operational? In orbit
76 TERRIERS May 18, 1999 Atmospheric research, satellite failed shortly after achieving orbit ? In orbit
77 FUSE June 23, 1999 Ultraviolet astronomy October 18, 2007 In orbit
78 IMAGE March 25, 2000 Magnetospheric research December 18, 2005 In orbit
79 HETE October 9, 2000 UV, X-Ray, and gamma ray astronomy Operational (7 years) In orbit
80 WMAP June 30, 2001 Microwave astronomy Operational (6 years) In L2 orbit
81 RHESSI February 5, 2002 X-ray and gamma ray solar flare imaging operational? In orbit
82 CHIPSat January 13, 2003 Ultraviolet spectroscopy and astronomy operational? In orbit
83 GALEX April 28, 2003 Ultraviolet astronomy Operational (4 years) In orbit
84 SWIFT November 20, 2004 Gamma ray astronomy Operational (3 years) In orbit
85 THEMIS February 17, 2007 Magnetospheric research Operational In orbit
86 THEMIS February 17, 2007 Magnetospheric research Operational In orbit
87 THEMIS February 17, 2007 Magnetospheric research Operational In orbit
88 THEMIS February 17, 2007 Magnetospheric research Operational In orbit
89 THEMIS February 17, 2007 Magnetospheric research Operational In orbit
90 AIM April 25, 2007 Noctilucent cloud observation Operational In orbit

[edit] References

  1. ^ Explorer 12. NASA.

[edit] See also

[edit] External links

v • d • e
Explorer program
Italics indicate probes that failed to deploy or otherwise malfunctioned
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