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Explorer





Explorer 1
Explorer 1
A long and ongoing series of small American scientific spacecraft. Explorer 1, the first successful American satellite, discovered the Van Allen Belts. Explorer 6 took the first photo of Earth from space. Subprograms of the Explorer series have included ADE (Air Density Explorer), AE (Atmosphere Explorer), DME (Direct Measurement Explorer), EPE (Energetic Particles Explorer), GEOS (Geodetic Earth Orbiting Satellite), IE (Ionosphere Explorer), and IMP (Interplanetary Monitoring Platform). Among the more recent Explorers are IUE (International Ultraviolet Explorer) and COBE (Cosmic Background Explorer). Subcategories of the modern Explorer program include SMEX (Small Explorer), MIDEX (Medium-class Explorer), UNEX (University-class Explorer), and Missions of Opportunity, while the themes of the program are the Astronomical Search for Origins and Planetary Systems, the Sun-Earth Connection, and the Structure and Evolution of the Universe.

The name "Explorer," designating NASA's scientific satellite series, originated before NASA was formed. "Explorer" was used in the 1930s for the US Army Air Service-National Geographic stratosphere balloons. On Jan. 31, 1958, when the first U.S. satellite was orbited by the US Army as a contribution to the International Geophysical Year (IGY), Secretary of the Army Wilbur M. Brucker announced the satellite's name, Explorer 1. The name indicated the mission of this first satellite and its NASA successor – to explore the unknown.


Explorer launch date launch vehicle launch site orbit mass
(kg)
1 Feb. 1, 1958 Juno 1 Cape Canaveral 358 × 2,550 × 33° 5
2 Mar. 5, 1958 Juno 1 Cape Canaveral failed to reach orbit 5
3 Mar. 26, 1958 Juno 1 Cape Canaveral 186 × 2,799 × 33° 5
4 Jul. 26, 1958 Jupiter Cape Canaveral 263 × 2,213 × 50° 8
5 Aug. 24, 1958 Juno 1 Cape Canaveral failed to reach orbit 17
6 Aug. 7, 1959 Thor-Able Cape Canaveral 237 × 41,900 × 47° 64
7 Oct. 13, 1959 Juno 2 Cape Canaveral 573 × 1,073 × 50° 42
8 Nov. 3, 1960 Juno 2 Cape Canaveral 417 × 2,288 × 50° 41
9 Feb. 16, 1961 Scout X-1 Wallops Island 545 × 2,225 × 39° 7
10 Mar. 25, 1961 Delta Cape Canaveral highly elliptical 35
11/Met. Sat 1 Apr. 27, 1961 Juno 2 Cape Canaveral 486 × 1,786 × 29° 37
12/EPE-1 Aug. 16, 1961 Delta Cape Canaveral 790 × 76,620 × 33° 38
13/Met. Sat 2 Aug. 25, 1961 Scout X-1 Wallops Island wrong orbit 86
14/EPE-2 Oct. 2, 1962 Delta A Cape Canaveral 2,601 × 96,189 × 43° 40
15/EPE-3 Oct. 27, 1962 Delta A Cape Canaveral 300 × 17,438 × 18° 44
16/Met. Sat 3 Dec. 16, 1962 Scout X-3 Wallops Island 744 × 1,159 × 52° 100
17/AE 1 Apr. 5, 1963 Delta B Cape Canaveral 254 × 891 × 57° 185
18/IMP-1 Nov. 26, 1963 Delta C Cape Canaveral 192 × 197,616 × 33° 62
19/ADE 1 Dec. 19, 1963 Scout X-4 Vandenberg 597 × 2,391 × 79° 7
20/IE Aug. 25, 1964 Delta C Cape Canaveral 855 × 1,001 × 80° 44
21/IMP-2 Oct. 4, 1964 Delta C Cape Canaveral 191 × 95,590 × 34° 62
22/BE 2 Oct. 9, 1964 Scout X-4 Vandenberg 872 × 1,053 × 80° 52
23/Met. Sat. 4 Nov. 6, 1964 Scout X-4 Wallops Island 463 × 980 × 52° 134
24/ADE 2 Nov. 21, 1964 Scout X-4 Wallops Island 530 × 2,498 × 81° 9
25/Injun 4 " " " 524 × 2,349 × 81° 40
26/EPE-4 Dec. 21, 1964 Delta C Cape Canaveral 284 × 10,043 × 20° 46
27/BE 3 Apr. 29, 1965 Scout X-4 Wallops Island 932 × 1,309 × 41° 60
28/IMP-3 May 29, 1965 Delta C Cape Canaveral 229 × 261,206 × 31° 58
29/GEOS 1 Nov. 6, 1965 Delta E Cape Canaveral 1,114 × 2,273 × 59° 175
30/Solrad 8 Nov. 19, 1965 Scout X-4 Wallops Island 667 × 871 × 60° 57
31/DME Nov. 29, 1965 Thor Agena A Vandenberg 502 × 2,857 × 80° 99
32/AE 2 May 25, 1966 Delta C Cape Canaveral 282 × 2,723 × 65° 225
33/IMP-4 Jul. 1, 1966 Delta E Cape Canaveral 85,228 × 481,417 × 41° 93
34/IMP-6 May 24, 1967 Delta E Vandenberg 242 × 214,379 × 67° 75
35 IMP-5 Jul. 19, 1967 Delta E Cape Canaveral n/a 104
36/GEOS 2 Jan. 11, 1968 Delta E Vandenberg 1,079 × 1,572 × 106° 209
37/Solrad 9 Mar. 5, 1968 Scout B Wallops Island 353 × 433 × 59° 198
38/RAE 1 Jul. 4, 1968 Delta J Vandenberg 5,835 × 5,861 × 121° 190
39/ADE 3 Aug. 8, 1968 Scout B Vandenberg 670 × 2,583 × 81° 9
40/Injun 5 " Scout B Vandenberg 677 × 2,494 × 81° 70
41/IMP-7 Jun. 21, 1969 Delta E Vandenberg 80,374 × 98,159 × 86° 174
42/SAS 1 Dec. 12, 1970 Scout B San Marco 521 × 570 × 3° 143
43/IMP-8 Mar. 13, 1971 Delta M Cape Canaveral 1,845 × 203,130 × 31° 288
44 Solrad 10 Jul. 8, 1971 Scout B Wallops Island 433 × 632 × 51° 118
45/SSS-1 Nov. 15, 1971 Scout B San Marco 272 × 18,149 × 3° 52
46/MTS Aug. 13, 1972 Scout D Wallops Island 492 × 811 × 38° 136
47/IMP-9 Sep. 22, 1972 Delta 1914 Cape Canaveral 201,100 × 235,600 × 17° 376
48/SAS 2 Nov. 16, 1972 Scout D San Marco 526 × 526 × 1° 185
49/RAE 2 Jun. 10, 1973 Delta 1914 Cape Canaveral 1,053 × 1,064 × 56° 328
50/IMP-11 Oct. 25, 1973 Delta 1914 Cape Canaveral 141,185 × 288,857 × 28° 371
51/AE 3 Dec. 16, 1973 Delta 1914 Vandenberg 155 × 4,306 × 68° 658
52/Hawkeye Jun. 3, 1974 Scout D Vandenberg 469 × 125,569 × 89° 27
53/SAS 3 May 7, 1975 Scout F San Marco 498 × 507 × 3° 195
54/AE 4 Oct. 6, 1975 Delta 2914 Vandenberg 151 × 3,819 × 90° 676
55/AE 5 Nov. 20, 1975 Delta 2914 Cape Canaveral 154 × 3,002 × 20° 721
56/ISEE-1 Oct. 22, 1977 Delta 2914 Cape Canaveral 436 × 137,806 × 13° 340
57/IUE Jan. 26, 1978 Delta 2914 Cape Canaveral 30,285 × 41,296 × 34° 672
58/HCMM Apr. 26, 1978 Scout D Vandenberg 560 × 641 × 98° 134
59/ISEE-3 Aug. 12, 1978 Delta 2914 Cape Canaveral 181 × 1,089,200 × 1° 479
60/SAGE Feb. 18, 1979 Scout D Wallops Island 456 × 506 × 55° 147
61 Magsat Oct. 30, 1979 Scout G Vandenberg 352 × 561 × 97° 181
62 DE-1 Aug. 3, 1981 Delta 3914 Vandenberg 568 × 23,289 × 90° 424
63 DE-2 " " " 309 × 1,012 × 80° 420
64 SME Oct. 6, 1981 Delta 2914 Cape Canaveral 335 × 337 × 98° 437
65 AMPTE/CCE Aug. 16, 1984 Delta 3925 Cape Canaveral 1,121 × 49,671 × 5° 242
66 COBE Nov. 18, 1989 Delta 5920 Vandenberg 872 × 886 × 99° 2,265
67 EUVE Jun. 7, 1992 Delta 6925 Cape Canaveral 510 × 524 × 28° 3,275
68 SAMPEX Jul. 3, 1992 Scout G Vandenberg 506 × 670 × 82° 158
69 RXTE Dec. 30, 1995 Delta 7920 Cape Canaveral 409 × 409 × 29° 3,200
70 FAST Aug. 21, 1996 Pegasus XL Vandenberg 353 × 4,163 × 83° 187
71 ACE Aug. 25, 1997 Delta 7920 Cape Canaveral halo 785
72 SNOE Feb. 26, 1998 Pegasus XL Vandenberg 529 × 581 × 98° 120
73 TRACE Apr. 2, 1998 Pegasus XL Vandenberg 602 × 652 × 98° 250
74 SWAS Dec. 6, 1998 Pegasus XL Vandenberg 637 × 651 × 70° 288
75 WIRE Mar. 5, 1999 Pegasus XL Vandenberg 540 × 590 × 98° 259
76 TERRIERS May 18, 1999 Pegasus XL Vandenberg 537 × 552 × 98° 120
77 FUSE Jun. 24, 1999 Delta 7925 Cape Canaveral 753 × 769 × 25° 1,400
78 IMAGE Mar. 25, 2000 Delta 7326 Vandenberg 1,000 × 45,922 × 40° 494
79/HETE-2 Oct. 9, 2000 Pegasus Kwajalein 598 × 641 × 1.9° 124
80/MAP Jun. 30, 2001 Delta 7425 Cape Canaveral 1,000 × 45,922 × 40° 840
81/RHESSI Feb. 5, 2002 Pegasus Cape Canaveral 1,000 × 45,922 × 40° 293


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