Editing Explorers Program (section)

== Launched spacecraft ==
Explorers Program name numbers can be found in the [[NASA Space Science Data Coordinated Archive|NSSDC master catalog]], typically assigned to each spacecraft in a mission. These numbers were not officially assigned until after 1975.<ref>{{cite web |url=http://www.planet4589.org/space/misc/explorer.html |title=Explorers Program |website=planet4589.org |access-date=2016-02-24 |archive-url=https://web.archive.org/web/20160303194728/http://www.planet4589.org/space/misc/explorer.html |archive-date=2016-03-03 |url-status=dead}}</ref>

{| class="wikitable sortable" style="margin:1em auto;"
|+ '''Explorers Program satellites'''<ref name= "nssdc_list">{{cite web |url=https://nssdc.gsfc.nasa.gov/multi/explorer.html |title=NASA's Explorers Program Satellites |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref><ref>{{cite web |url=http://www.planet4589.org/space/misc/explorer.html |title=Explorers Program |publisher=Planet4589.org |access-date=2018-04-20 |archive-url=https://web.archive.org/web/20160303194728/http://www.planet4589.org/space/misc/explorer.html |archive-date=2016-03-03 |url-status=dead}}</ref><ref>{{cite web |url=https://history.nasa.gov/explorer.html |title=Explorers Spacecraft Series |publisher=History.nasa.gov |access-date=2018-04-20}} {{PD-notice}}</ref><ref name=skyrocket>{{cite web |url=http://space.skyrocket.de/doc_sat/explorer.htm |title=Explorers Program |website=space.skyrocket.de |access-date=2016-02-24}}</ref> 
|-

! No.
! Name(s)
! Launch date (UTC)
! Rocket
! Mass (kg)
! Orbit regime
! End of data
! Re-entry<br><ref>{{cite web |url=http://www.unoosa.org/oosa/osoindex/search-ng.jspx?match=explorer |title=Search OSOidx |publisher=Unoosa.org |date=2018-04-23 |access-date=2018-04-28}}</ref>
! Mission/Notes
|-

! 1
| [[Explorer 1]]
| 1 February 1958
| [[Juno I]]
| 14
| MEO
| 23 May 1958
| 31 March 1970
| First American satellite, third satellite to achieve orbit; discovered the [[Van Allen radiation belt]]; launched by the [[United States Army|U.S. Army]]<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1958-001A |title=Explorer 1 (1958-001A) |publisher=NASA |date=7 January 2022 |access-date=12 February 2022}} {{PD-notice}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| 2
| [[Explorer 2]]
| 5 March 1958
| [[Juno I]]
| 15
| ''Failed''
| —
| —
| Failed to achieve orbit.<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=EXPLR2 |title=Explorer 1 (EXPLR2) |publisher=NASA |date=7 January 2022 |access-date=12 February 2022}} {{PD-notice}}</ref>
|-

! 3
| [[Explorer 3]]
| 26 March 1958
| [[Juno I]]
| 14
| MEO
| 27 June 1958
| 27 June 1958
| Energetic particle studies helped confirm the presence of [[Van Allen radiation belt]]<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1958-003A |title=Explorer 3 (1958-003A) |publisher=NASA |date=7 January 2022 |access-date=12 February 2022}} {{PD-notice}}</ref>
|-

! 4
| [[Explorer 4]]
| 26 July 1958
| [[Juno I]]
| 26
| MEO
| 5 October 1958
| 23 October 1959
| Monitor charged particles inside Van Allen belts from nuclear detonations (during [[Operation Argus]])<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1958-005A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| 5
| [[Explorer 5]]
| 24 August 1958
| [[Juno I]]
| 17
| ''failed''
| —
| —
| Planned in conjunction with Explorer 4, but launch failed<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=EXPLR5 |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"|  —
| [[Explorer S-1]] (7X)
| 16 July 1959
| [[Juno II]]
| 42
| ''failed''
| —
| —
| Planned to measure Earth's radiation balance, but destroyed within seconds by range safety<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=EXP-7X |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 6
| [[Explorer 6]] (S-2, Able 3)
| 7 August 1959
| [[Thor-Able]]
| 64
| HEO
| 6 October 1959
| 12 July 1961
| Magnetosphere research and digital telemetry; first NASA launch, first Earth photo from orbit<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1959-004A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref><ref name="space-timeline">{{cite web |url=https://www.space.com/4422-timeline-50-years-spaceflight.html |title=Timeline: 50 Years of Spaceflight |website=space.com |date=28 September 2012 |access-date=24 June 2019}}</ref>
|-

! 7
| [[Explorer 7]] (S-1A)
| 13 October 1959
| [[Juno II]]
| 42
| LEO
| 24 August 1961
| In orbit
| Micrometeoroids and energetic particle studies, first satellite to measure Earth's climate<ref>{{cite web |url=https://www.ssec.wisc.edu/media/spotlight/explorer7.html |title=50 Year Anniversary of Explorer 7 Launch |publisher=ssec.wisc.edu |access-date=2018-04-20 |archive-date=10 June 2017 |archive-url=https://web.archive.org/web/20170610094052/http://www.ssec.wisc.edu/media/spotlight/explorer7.html |url-status=dead}}</ref><ref>{{cite web |last=Evans |first=Gareth |url=https://www.aerospace-technology.com/features/feature78185/ |title=Nasa's High-Tech Climate Monitoring |publisher=Aerospace Technology |date=2010-04-05 |access-date=2018-04-20}}</ref><ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1959-009A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20 }} {{PD-notice}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| –
| [[Explorer S-46 (satellite)|S-46A]] (IE-B)
| 23 March 1960
| [[Juno II]]
| 16
| ''failed''
| —
| —
| Analyze electron and proton radiation energies, failed to achieve orbit<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=EXS-46 |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 8
| [[Explorer 8]] (S-30)
| 3 November 1960
| [[Juno II]]
| 41
| LEO
| 27 December 1960
| 27 March 2012
| Measured atmospheric composition of the ionosphere<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1960-014A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| –
| [[S-56 (satellite)|S-56]]
| 4 December 1960
| [[Scout X-1]]
| 6
| ''failed''
| —
| —
| Atmosphere density measurement, but failed to achieve orbit<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=EXS-56 |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 9
| [[Explorer 9]] (S-56A)
| 16 February 1961
| [[Scout X-1]]
| 36
| LEO
| 9 April 1964
| 9 April 1964
| Atmospheric density measurements, first spacecraft placed in orbit by a solid-fuel rocket<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1961-004A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| –
| [[S-45 (satellite)|S-45]]
| 24 February 1961
| [[Juno II]]
| 34
| ''failed''
| —
| —
| Ionosphere research, but failed to achieve orbit<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=EXS-451 |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 10
| [[Explorer 10]] (P 14)
| 25 March 1961
| [[Delta (rocket family)|Thor-Delta]]
| 79
| HEO
| 25 March 1961
| 1 June 1968
| Investigated the magnetic field between the Earth and Moon<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1961-010A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 11
| [[Explorer 11]] (S 15)
| 27 April 1961
| [[Juno II]]
| 37
| LEO
| 17 November 1961
| In orbit
| Gamma ray astronomy<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1961-013A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| –
| [[S-45A]]
| 25 May 1961
| [[Juno II]]
| 34
| ''failed''
| —
| —
| Ionosphere research, failed to achieve orbit. Last Juno II launch.<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=EXS-452 |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| –
| [[S-55 (satellite)]] (Meteoroid Satellite-A, Micrometeorite Explorer)
| 30 June 1961
| [[Scout (rocket)|Scout X-1]]
| 85
| ''failed''
| —
| —
| Micrometeoroid research, failed to achieve orbit<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=EXS-55 |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 12
| [[Explorer 12|EPE-A]] (S 3, Energetic Particle Explorer-A)
| 16 August 1961
| [[Thor-Delta]]
| 38
| HEO
| 6 December 1961
| 1 September 1963
| Energetic particle research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1961-020A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|- style="background: #ffb;"

! style="background: #FFB;" | 13
| [[Explorer 13]] (S-55A)
| 25 August 1961
| [[Scout X-1]]
| 86
| LEO
| 28 August 1961
| 28 August 1961
| Micrometeoroid research; partial failure<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1961-022A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 14
| [[Explorer 14|EPE-B]] (Energetic Particle Explorer-B)
| 2 October 1962
| [[Delta A]]
| 40
| HEO
| 11 August 1963
| 1 July 1966
| Energetic particle research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1962-051A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 15
| [[Explorer 15|EPE-C]] (S-3B, Energetic Particle Explorer-C)
| 27 October 1962
| [[Delta A]]
| 44
| HEO
| 30 January 1963
| 15 January 1978
| Energetic particle research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1962-059A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 16
| [[Explorer 16|S-55B]]
| 16 December 1962
| [[Scout (rocket)|Scout X-3]]
| 101
| LEO
| 22 July 1963
| In orbit
| Micrometeoroid research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1962-070A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 17
| [[Explorer 17|AE-A (S-6, Atmosphere Explorer-A)]]
| 3 April 1963
| [[Delta B]]
| 184
| LEO
| 10 July 1963
| 24 November 1966
| Atmospheric research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-009A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 18
| [[Explorer 18|IMP-A]] (IMP 1, Interplanetary Monitoring Platform-A)
| 27 November 1963
| [[Delta C]]
| 138
| HEO
| 10 May 1965
| 30 December 1965
| Magnetospheric research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-046A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 19
| [[Explorer 19|AD-A (Atmospheric Density-A)]]
| 19 December 1963
| [[Scout (rocket)|Scout X-4]]
| 8
| LEO
| 10 May 1981
| 10 May 1981
| Atmospheric density measurements<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-053A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| –
| BE-A ([[Beacon Explorer-A]], S-66A)
| 19 March 1964
| [[Delta B]]
| 114
| ''failed''
| —
| —
| Launch failure<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=EXS-66A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 20
| [[Explorer 20|IE-A]] (S 48, TOPSI, Ionosphere Explorer-A)
| 25 August 1964
| [[Scout (rocket)|Scout X-4]]
| 45
| LEO
| 29 December 1965
| In orbit
| Ionosphere research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-051A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 21
| [[Explorer 21|IMP-B]] (IMP 2, Interplanetary Monitoring Platform-B)
| 4 October 1964
| [[Delta C]]
| 135
| HEO
| 13 October 1965
| 30 January 1966
| Magnetospheric research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-060A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 22
| [[Explorer 22|BE-B]] (Beacon Explorer-B, S-66B)
| 10 October 1964
| [[Scout (rocket)|Scout X-4]]
| 53
| LEO
| February 1970
| In orbit
| Ionospheric and geodetic research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-064A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 23
| [[Explorer 23|S 55C]]
| 6 November 1964
| [[Scout (rocket)|Scout X-4]]
| 134
| LEO
| 7 November 1965
| 29 June 1983
| Micrometeoric research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-074A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 24
| [[Explorer 24|AD-B]] (Atmospheric Density-B)
| 21 November 1964
| [[Scout (rocket)|Scout X-4]]
| 9
| MEO
| 18 October 1968
| 18 October 1968
| Atmospheric density measurements<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-076A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 25
| [[Injun (satellite)|Injun 4]] (IE-B, Ionosphere Explorer-B)
| 21 November 1964
| [[Scout (rocket)|Scout X-4]]
| 40
| LEO
| December 1966
| In orbit
| Ionospheric research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-076B |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 26
| [[Explorer 26|EPE-D (Energetic Particle Explorer-D)]]
| 21 December 1964
| [[Delta C]]
| 46
| MEO
| 27 December 1967
| 23 August 2021
| High energy particle observations<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1964-086A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 27
| [[Explorer 27|BE-C (Beacon Explorer-C, S-66C)]]
| 29 April 1965
| [[Scout (rocket)|Scout X-4]]
| 61
| LEO
| 20 July 1973
| In orbit
| Magnetospheric research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-032A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 28
| [[Explorer 28|IMP-C]] (IMP 3, Interplanetary Monitoring Platform-C)
| 29 May 1965
| [[Delta C]]
| 128
| HEO
| 12 May 1967
| 4 July 1968
| Magnetospheric research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-042A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 29
| [[Explorer 29|GEOS 1]] (GEOS-A, Geodetic Earth Orbiting Satellite-1)
| 6 November 1965
| [[Delta E]]
| 387
| LEO
| 23 June 1978
| In orbit
| Geodetic Earth monitoring<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-089A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 30
| [[Solrad 8|SOLRAD 8]] (SE-A)
| 19 November 1965
| [[Scout (rocket family)|Scout X-4]]
| 57
| LEO
| 5 November 1967
| In orbit
| Solar radiation monitoring (Cover for covert [[Signals intelligence|ELINT]] mission)<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-093A |title=NASA - NSSDCA - Spacecraft |publisher=National Space Science Data Center |access-date=2018-04-20}} {{PD-notice}}</ref>
|-

! 31
| [[Explorer 31|DME-A]] (Direct Measurements Explorer)
| 29 November 1965
| [[Thor-Agena]] B
| 99
| LEO
| 1 October 1969
| In orbit
| Ionospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-098B |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 32
| [[Explorer 32|AE-B (Atmosphere Explorer-B)]]
| 25 May 1966
| [[Delta C]]1
| 225
| LEO
| March 1967
| 22 February 1985
| Atmospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-044A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 33
| [[Explorer 33|IMP-D (AIMP 1, Interplanetary Monitoring Platform-D)]]
| 1 July 1966
| [[Delta E]]1
| 212
| HEO
| 21 September 1971<ref>{{cite web| url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-058A| title=Explorer 33 (NSSDC ID: 1966-058A)| publisher=NASA / National Space Science Data Center| date=2008-04-02| access-date=2008-07-04}}</ref>
| In orbit
| Magnetospheric research
|-

! 34
| [[Explorer 34|IMP-F]] (IMP 4, Interplanetary Monitoring Platform-F)
| 24 May 1967
| [[Delta E]]1
| 163
| MEO
| 3 May 1969
| 3 May 1969
| Magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1967-051A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center|access-date=2018-04-20}}</ref>
|-

! 35
| [[Explorer 35|IMP-E (AIMP 2, Interplanetary Monitoring Platform-E)]]
| 19 July 1967
| [[Delta E]]1
| 230
| [[Lunar orbit|Lunar]]
| 24 June 1973
| Lunar orbit
| Magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1967-070A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 36
| [[GEOS 2]] (GEOS-B, Geodetic Earth Orbiting Satellite-2)
| 11 January 1968
| [[Delta E]]1
| 469
| LEO
| 1 July 1982
| In orbit
| Geodetic Earth monitoring<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1968-002A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 37
| [[SOLRAD 9]] (SE B)
| 5 March 1968
| [[Scout B]]
| 198
| LEO
| 30 April 1974
| 16 November 1990
| Solar radiation monitoring<br>(Cover for covert [[ELINT]] mission)<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1968-017A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center|access-date=2018-04-20}}</ref>
|-

! 38
| [[Explorer 38|RAE-A (RAE 1, Radio Astronomy Explorer-A)]]
| 4 July 1968
| [[Delta J]]
| 602
| MEO
| (~1969)
| In orbit
| Radio astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1968-055A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 39
| [[Explorer 39|AD-C]] (Atmospheric Density-C)
| 8 August 1968
| [[Scout B]]
| 9
| LEO
| 23 June 1971
| 22 June 1981
| Atmospheric density measurements<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1968-066A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 40
| [[Injun (satellite)|Injun 5]] (Injun C, IE-C, Ionosphere Explorer-C)
| 8 August 1968
| [[Scout B]]
| 71
| LEO
| June 1971
| In orbit
| Magnetospheric Research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1968-066B |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 41
| [[Explorer 41|IMP-G]] (IMP 5, Interplanetary Monitoring Platform-G)
| 21 June 1969
| [[Delta E]]1
| 145
| HEO
| 23 December 1972
| 23 December 1972
| Magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1969-053A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 42
| [[Uhuru (satellite)|Uhuru]] (SAS-A, SAS 1)
| 12 December 1970
| [[Scout B]]
| 142
| LEO
| 4 January 1975
| 5 April 1979
| X-ray astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-107A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 43
| [[Explorer 43|IMP-H]] (IMP 7, Interplanetary Monitoring Platform-H)
| 13 March 1971
| [[Delta M]]6
| 635
| MEO
| 2 October 1974
| 2 October 1974
| Magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1971-019A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 44
| [[SOLRAD 10]] (SE-C, SOLRAD-C)
| 8 July 1971
| [[Scout B]]
| 260
| LEO
| 30 June 1973
| 15 December 1979
| Solar radiation monitoring<br>(Cover for covert [[ELINT]] mission)<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1971-058A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 45
| [[Explorer 45|SSS-A]] (S-Cubed A)
| 15 November 1971
| [[Scout B]]
| 52
| MEO
| 30 September 1974
| 10 January 1992
| Magnetospheric research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1971-096A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20 }}</ref>
|-

! 46
| MTS ([[Meteoroid Technology Satellite]], METEC)<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1972-061A |title=NASA - NSSDCA - Spacecraft - Details |website=National Space Science Data Center |date=2016-02-12 |access-date=2016-02-24}}</ref>
| 13 August 1972
| [[Scout (rocket)|Scout D-1]]
| 90
| LEO
| 4 November 1974
| 2 November 1979
| Micrometeoroids research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1972-061A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 47
| [[Explorer 47|IMP-I]] (IMP 6, Interplanetary Monitoring Platform-I)
| 23 September 1972
| [[Delta 1000|Delta 1604]]
| 635
| HEO
| 31 October 1978
| In orbit
| Magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1972-073A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 48
| [[Second Small Astronomy Satellite|SAS-B (Small Astronomy Satellite-B, SAS 2)]]
| 15 November 1972
| [[Scout (rocket)|Scout D-1]]
| 166
| LEO
| 8 June 1973
| 20 August 1980
| X-ray astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1972-091A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 49
| [[Explorer 49|RAE-B (RAE 2, Radio Astronomy Explorer-B)]]
| 10 June 1973
| [[Delta 1000|Delta 1913]]
| 328
| [[Lunar orbit|Lunar]]
| 26 April 1977
| Presumed crashed into Moon sometime after August 1977<ref name="explorer49nssdc"/>
| Radio astronomy<ref name="explorer49nssdc">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-039A|title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 50
| [[Explorer 50|IMP-J]] (IMP 8, Interplanetary Monitoring Platform-J)
| 26 October 1973
| [[Delta 1000|Delta 1604]]
| 371
| HEO
| 7 October 2006
| In orbit
| Magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-078A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 51
| [[Explorer 51|AE-C]] (Atmosphere Explorer-C)
| 16 December 1973
| [[Delta 1000|Delta 1900]]
| 658
| LEO
| (12 December 1978)
| 12 December 1978
| Atmospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-101A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 52
| [[Explorer 52|Hawkeye 1]] (Injun-F, Injun 6, IE-D, Ionosphere Explorer-D)
| 3 June 1974
| [[Scout (rocket)|Scout E-1]]
| 23
| HEO
| 28 April 1978
| 28 April 1978
| Magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1974-040A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 53
| [[Third Small Astronomy Satellite|SAS-C (Small Astronomy Satellite-C, SAS 3)]]
| 7 May 1975
| [[Scout (rocket)|Scout F-1]]
| 197
| LEO
| 7 April 1979
| 9 April 1979
| X-ray astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-037A |title=NASA - NSSDCA - Spacecraft - Details |publisher=National Space Science Data Center |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 54
| [[Explorer 54|AE-D]] (Atmosphere Explorer-D)
| 6 October 1975
| [[Delta 2000|Delta 2910]]
| 681
| LEO
| 29 January 1976
| 12 March 1976
| Atmospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-096A |title=AE-D |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 55
| [[Explorer 55|AE-E]] (Atmosphere Explorer-E)
| 20 November 1975
| [[Delta 2000|Delta 2910]]
| 735
| LEO
| 25 September 1980
| 10 June 1981
| Atmospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-107A |title=AE-E |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| —
| [[Dual Air Density Explorer|DADE-A]] (Dual Air Density Explorer-A)
| 5 December 1975
| [[Scout (rocket)|Scout F-1]]
| 40
| ''failed''
| —
| —
| Atmospheric research; failed during launch<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=DADE-A |title=DADE-A |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| —
| [[Dual Air Density Explorer|DADE-B]] (Dual Air Density Explorer-B)
| 5 December 1975
| [[Scout (rocket)|Scout F-1]]
| 43
| ''failed''
| —
| —
| Atmospheric research; failed during launch<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=DADE-B |title=DADE-B |publisher=National Space Science Data Center |access-date=2018-04-20}}</ref>
|-

! 56
| [[ISEE-1]]  (ISEE-A)
| 22 October 1977
| [[Delta 2000|Delta 2914]]
| 340
| HEO
| 26 September 1987
| 26 September 1987
| Magnetospheric research; launched with ESA's [[ISEE-2]]; co-mission with ISEE 3<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1977-102A |title=ISEE 1 |publisher=NASA - NSSDCA |access-date=2018-04-20}}</ref>
|-

! 57
| [[International Ultraviolet Explorer|IUE]]
| 26 January 1978
| [[Delta 2000|Delta 2914]]
| 669
| MEO
| 30 September 1996
| In orbit
| Ultraviolet astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1978-012A |title=IUE |publisher=NASA - NSSDCA |access-date=2018-04-20}}</ref>
|-

! 58
| [[Heat Capacity Mapping Mission|HCMM]] (AEM-A)
| 26 April 1978
| [[Scout (rocket)|Scout F]]
| 117
| LEO
| 30 September 1980
| December&nbsp;22, 1981
| Thermal mapping of the Earth<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1978-041A |title= HCMM |publisher=NASA - NSSDCA |access-date=2018-04-20}}</ref>
|-

! 59
| [[International Cometary Explorer|ICE]] (ISEE 3, ISEE-C)
| 12 August 1978
| [[Delta 2000|Delta 2914]]
| 390
| [[Lissajous orbit|Sun–Earth L<sub>1</sub>]]
| 16 September 2014
| [[Heliocentric orbit]]
| Magnetospheric research; heliocentric mission, re-purposed in 1982 as a cometary probe (renamed International Cometary Explorer). First spacecraft to be placed at a libration point, and first one to perform a flyby of a comet.<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1978-079A |title= ISEE 3 |publisher=NASA - NSSDCA |access-date=2018-04-20}}</ref><ref name="space-timeline" />
|-

! 60
| [[Stratospheric Aerosol and Gas Experiment|SAGE]] (AEM-B)
| 18 February 1979
| [[Scout (rocket)|Scout D-1]]
| 149
| LEO
| 7 January 1982
| 11 April 1989
| Stratospheric aerosol and ozone data<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1979-013A |title= SAGE |publisher=NASA - NSSDCA |access-date=2018-04-20 }}</ref>
|-

! 61
| [[Magsat|MAGSAT]] (AEM-C)
| 30 October 1979
| [[Scout (rocket)|Scout G-1]]
| 158
| LEO
| 6 May 1980
| 11 June 1980
| Mapped the near surface magnetic field of the Earth<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1979-094A |title=Magsat |publisher=NASA - NSSDCA |access-date=2018-04-20}}</ref>
|-

! 62
| [[Dynamics Explorer 1]] (DE-1)
| 3 August 1981
| [[Delta (rocket)|Delta 3913]]
| 424
| MEO
| 28 February 1991
| In orbit
| Magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1981-070A |title=Dynamics Explorer 1 |publisher=NASA - NSSDCA |access-date=2018-04-20}}</ref>
|-

! 63
| [[Dynamics Explorer 2]] (DE-2)
| 3 August 1981
| [[Delta (rocket)|Delta 3913]]
| 420
| LEO
| 19 February 1983
| 19 February 1983
| Magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1981-070B |title= Dynamics Explorer 2 |publisher=NASA - NSSDCA |access-date=2018-04-20}}</ref>
|-

! 64
| [[Solar Mesosphere Explorer|SME]]
| 6 October 1981
| [[Delta (rocket)|Delta 2310]]
| 145
| LEO
| 4 April 1989
| 5 March 1991
| Atmospheric research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1981-100A |title= SME |publisher=NASA - NSSDCA |access-date=2018-04-20 |url-status=live |archive-url=https://web.archive.org/web/20200404213307/https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1981-100A |archive-date= 4 April 2020 }}</ref>
|-

! 65
| [[AMPTE-CCE]]
| 16 August 1984
| [[Delta (rocket)|Delta 3924]]
| 242
| MEO
| 12 July 1989
| In orbit
| [[Magnetosphere|Magnetosphere research]]<ref name="Display">{{citation-attribution|1={{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1984-088A|title=AMPTE-CEE (1984-088A)|publisher=NSSDCA |access-date=26 November 2021}} }}</ref>
|-

! 66
| [[Cosmic Background Explorer|COBE]]
| 18 November 1989
| [[Delta (rocket)|Delta 5920]]
| 2,206
| LEO
| 23 December 1993
| In orbit
| Microwave astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1989-089A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|-

! 67
| [[Extreme Ultraviolet Explorer|EUVE]] (BERKSAT)
| 7 June 1992
| [[Delta II]] 6920-X
| 3,275
| LEO
| 31 January 2001
| 30 January 2002
| Ultraviolet astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1992-031A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|-

! 68
| [[Solar Anomalous and Magnetospheric Particle Explorer|SAMPEX]]
| 3 July 1992
| [[Scout (rocket)|Scout G-1]]
| 158
| LEO
| 30 June 2004<ref>{{cite web|url=http://www.srl.caltech.edu/sampex/DataCenter/ |title=The SAMPEX Data Center |website=Srl.caltech.edu |access-date=2016-02-24}}</ref>
| 13 November 2012.<ref>{{cite web |url=http://www.aerospace.org/cords/reentry-predictions/upcoming-reentries/1992-038a/ |archive-url=https://archive.today/20130224130248/http://www.aerospace.org/cords/reentry-predictions/upcoming-reentries/1992-038a/ |url-status=dead |archive-date=2013-02-24 |title=SAMPEX &#124; The Aerospace Corporation |website=Aerospace.org |access-date=2016-02-24 }}</ref>
| SMEX: magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1992-038A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|-

! 69
| [[Rossi X-ray Timing Explorer|RXTE]]
| 30 December 1995
| [[Delta II]] 7920
| 3,200
| LEO
| 3 January 2012 
| 30 April 2018<ref>{{cite web |last=Reddy |first=Francis |url=https://phys.org/news/2018-05-nasa-rossi-x-ray-explorer-scientific.html |title=Nasa's Rossi X-ray Timing Explorer leaves scientific legacy |website=[[Phys.org]] |date=2018-05-04 |access-date=2019-02-18}}</ref>
| MIDEX: X-ray astronomy<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1995-074A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20 }}</ref>
|-

! 70
| [[Fast Auroral Snapshot Explorer|FAST]]
| 21 August 1996
| [[Pegasus XL]]
| 187
| LEO
| 4 May 2009
| In orbit
| SMEX: auroral phenomena<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1996-049A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| —
| [[High Energy Transient Explorer|HETE 1]]
| 4 November 1996
| [[Pegasus XL]]
| 128
| LEO
| —
| 7 April 2002
| Separation failure, mission relaunched as HETE 2<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1996-061A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20}}</ref>
|- style="background:#bfb;"

! style="background:#bfb;"| 71
| [[Advanced Composition Explorer|ACE]]
| 25 August 1997
| [[Delta II]] 7920
| 596
| [[Lissajous orbit|Sun–Earth L<sub>1</sub>]]
| '''Operational'''
| In [[Lissajous orbit|L<sub>1</sub> orbit]]
| MIDEX: solar/interplanetary/interstellar particle research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1997-045A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 72
| [[Student Nitric Oxide Explorer|SNOE]]
| 26 February 1998
| [[Pegasus XL]]
| 120
| LEO
| 13 December 2003
| 13 December 2003
| STEDI, UNEX: atmospheric research<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1998-012A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20 }}</ref>
|-

! 73
| [[TRACE]]
| 2 April 1998
| [[Pegasus XL]]
| 250
| LEO
| 21 June 2010<ref>{{cite web|url=http://trace.lmsal.com/ |title=< Welcome to T R A C E on-line > |website=Trace.lmsal.com |date=2010-06-21 |access-date=2016-02-24}}</ref> <!-- (Hibernation) ({{For year month day| year=1998 | month=04 | day=02}}) -->
| In orbit
| SMEX: solar observatory<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1998-020A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20 }}</ref>
|-

! 74
| [[Submillimeter Wave Astronomy Satellite|SWAS]]
| 6 December 1998
| [[Pegasus XL]]
| 288
| LEO
| 1 September 2005 <!-- (hiberation) -->
| In orbit
| SMEX: submillimeter astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1998-071A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|- style="background: #ffb;"

! style="background: #FFB;" | 75
| [[Wide Field Infrared Explorer|WIRE]]
| 5 March 1999
| [[Pegasus XL]]
| 250
| [[Sun-synchronous orbit|SSO]]
| 30 September 2000<ref>{{cite web |url=http://spider.ipac.caltech.edu/staff/laher/asteroseismology/wireobs2.html |title=Complete WIRE Star-Camera Observation History |publisher=Spider.ipac.caltech.edu |access-date=2018-04-20 |archive-date=6 August 2020 |archive-url=https://web.archive.org/web/20200806214243/http://spider.ipac.caltech.edu/staff/laher/asteroseismology/wireobs2.html |url-status=dead }}</ref>
| 10 May 2011<ref>{{cite web|author=WIRE Web Team |url=http://www.ipac.caltech.edu/wire/ |title=WIRE: The Wide Field Infrared Explorer |website=Ipac.caltech.edu |access-date=2016-02-24}}</ref>
| SMEX, Infrared astronomy, primary mission failed due to loss of coolant<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1999-011A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20 }}</ref>
|- style="background:#fbb;"

! style="background:#fbb;"| 76
| TERRIERS
| 18 May 1999
| [[Pegasus XL]]
| 120
| Polar LEO
| 18 May 1999
| In orbit
| STEDI: atmospheric research, satellite failed shortly after achieving orbit<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1999-026A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|-

! 77
| [[Far Ultraviolet Spectroscopic Explorer|FUSE]]
| 23 June 1999
| [[Delta II]] 7320
| 1,400
| LEO
| 18 October 2007
| In orbit
| MIDEX: ultraviolet astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1999-035A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|-

! 78
| [[IMAGE (spacecraft)|IMAGE]]
| 25 March 2000
| [[Delta II]] 7326
| 536
| Polar MEO
| 18 December 2005<ref>{{cite web|url=http://image.gsfc.nasa.gov/ |title=NASA - IMAGE Science Center |website=Image.gsfc.nasa.gov |access-date=2016-02-24}}</ref>
| In orbit
| MIDEX: magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2000-017A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|-

! 79
| [[High Energy Transient Explorer|HETE-2]]
| 9 October 2000
| [[Pegasus (rocket)|Pegasus-H]]
| 124
| LEO
| 28 March 2007<ref>{{cite web |url=https://science.nasa.gov/missions/hete-2/ |title=Missions - HETE-2 - NASA Science |website=Science.nasa.gov |access-date=2016-02-24 |archive-date=22 July 2016 |archive-url=https://web.archive.org/web/20160722132241/http://science.nasa.gov/missions/hete-2/ |url-status=dead }}</ref>
| In orbit
| MO: UV, X-ray, and gamma ray astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2000-061A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 80
| [[WMAP]]
| 30 June 2001
| [[Delta II]] 7425-10
| 840
| [[Lissajous orbit|Sun–Earth L<sub>2</sub>]]
| October 2010<ref name="graveyard">{{cite web |title=Mission Complete! WMAP fires its thrusters for the last time |url=http://news.discovery.com/space/mission-complete-wmap-fires-its-thrusters-for-the-last-time.html |access-date=8 November 2010 |archive-date=14 July 2012 |archive-url=https://web.archive.org/web/20120714021615/http://news.discovery.com/space/mission-complete-wmap-fires-its-thrusters-for-the-last-time.html |url-status=dead }}</ref>
| Heliocentric orbit
| MIDEX: microwave astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2001-027A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20}}</ref>
|-

! 81
| [[RHESSI]]
| 5 February 2002
| [[Pegasus XL]]
| 230
| LEO
| 16 August 2018
| Deorbited
| SMEX: X-ray and gamma ray solar flare imaging<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2002-004A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|-

|- style="background:#bfb;"
! style="background:#bfb;"| —
| [[INTEGRAL]]
| 17 October 2002
| [[Proton-K]] [[Blok D|Blok DM-2]]
| 4,000
| HEO
| '''Operational'''
| In orbit
| International: space telescope for observing gamma rays<ref>{{cite web|url=https://heasarc.gsfc.nasa.gov/docs/integral/integral.html |title=The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) |publisher=Heasarc.gsfc.nasa.gov |date=2002-10-17 |access-date=2018-04-28}}</ref>

|- 
! 82
| [[CHIPSat]]
| 13 January 2003
| [[Delta II]] 7320-10
| 60
| LEO
| 11 April 2008<ref>{{cite web|last=Savage |first=Sam |url=http://www.redorbit.com/news/space/1417075/chipsat_quietly_shut_down/ |title=CHIPSat Quietly Shut Down |website=Redorbit.com |date=2008-06-04 |access-date=2016-02-24}}</ref>
| In orbit
| UNEX: ultraviolet spectroscopy and astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2003-002B |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>

|- 
! 83
| [[GALEX]]
| 28 April 2003
| [[Pegasus XL]]
| 280
| LEO
| 28 June 2013<ref>{{cite web|url=http://www.galex.caltech.edu/newsroom/glx2013-03r.html |title=Press Release: NASA Decommissions Its Galaxy Hunter Spacecraft |website=Galex.caltech.edu |date=2013-06-28 |access-date=2016-02-24}}</ref>
| In orbit
| SMEX: ultraviolet astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2003-017A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20}}</ref>

|- style="background:#bfb;"
! style="background:#bfb;"| 84
| [[Neil Gehrels Swift Observatory|Swift]]
| 20 November 2004
| [[Delta II]] 7320-10C
| 1,470
| LEO
| '''Operational'''
| In orbit
| MIDEX: gamma ray astronomy<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2004-047A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20 }}</ref>

|- 
! —
| [[Suzaku (satellite)|Suzaku]] (Astro E2)
| 10 July 2005
| [[M-V]]
| 1,706
| LEO
| 2 September 2015
| In orbit
| MO: instrument on JAXA's Suzaku mission<ref>{{cite web|url=https://heasarc.gsfc.nasa.gov/docs/astroe/astroegof.html |title=HEASARC: Suzaku Guest Observer Facility |publisher=Heasarc.gsfc.nasa.gov |access-date=2018-04-28}}</ref>

|- style="background:#bfb;"
! style="background:#bfb;"| —
| [[TWINS]] A
| 28 June 2006
| [[Delta IV]] M+(4,2)
| ''classified''
| [[Molniya orbit|Molniya]]
| '''Operational'''
| In orbit
| MO: payload on Trumpet-F/O-1 1 ([[USA-184]])

|- style="background:#bfb;"
! style="background:#bfb;"| 85
| [[THEMIS (satellite)|THEMIS]] A
| 17 February 2007
|  [[Delta II]] 7925
| 77
| HEO
| '''Operational'''
| In orbit
| MIDEX: magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2007-004A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20}}</ref>
|- style="background:#bfb;"
! style="background:#bfb;"| 86
| [[THEMIS (satellite)|THEMIS]] B (ARTEMIS P1)
| 17 February 2007
| [[Delta II]] 7925
| 77
| [[Lunar orbit|Lunar]]
| '''Operational'''
| Lunar orbit
| MIDEX; Magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2007-004B |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|- style="background:#bfb;"
! style="background:#bfb;"| 87
| [[THEMIS (satellite)|THEMIS]] C (ARTEMIS P2)
| 17 February 2007
|  [[Delta II]] 7925
| 77
| [[Lunar orbit|Lunar]]
| '''Operational'''
| Lunar orbit 
| MIDEX: magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2007-004C |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>
|- style="background:#bfb;"
! style="background:#bfb;"| 88
| [[THEMIS (satellite)|THEMIS]] D
| 17 February 2007
|  [[Delta II]] 7925
| 77
| HEO
| '''Operational'''
| In orbit
| MIDEX: magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2007-004D |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20}}</ref>
|- style="background:#bfb;"
! style="background:#bfb;"| 89
| [[THEMIS (satellite)|THEMIS]] E
| 17 February 2007
| [[Delta II]] 7925
| 77
| HEO
| '''Operational'''
| In orbit
| MIDEX: magnetospheric research<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2007-004E |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20}}</ref>

|-
! 90
| [[Aeronomy of Ice in the Mesosphere|AIM]]
| 25 April 2007
| [[Pegasus XL]]
| 197
| [[Sun-synchronous orbit|SSO]]
| March 2023
| 19 August 2024 
| SMEX: [[noctilucent cloud]] observation<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2007-015A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20}}</ref>

|- style="background:#bfb;"
! style="background:#bfb;"| —
| [[TWINS]] B
| 13 March 2008
| [[Atlas V]] 411
| ''classified''
| [[Molniya orbit|Molniya]]
| '''Operational'''
| In orbit
| MO: payload on Trumpet-F/O-1 2 ([[USA-200]])

|- 
! —
| [[CINDI]] 
| 16 April 2008
| [[Pegasus XL]]
| 395
| LEO
| 28 November 2015
| 28 November 2015
| MO: instruments on [[C/NOFS]]

|- style="background:#bfb;"
! style="background:#bfb;"| 91
| [[Interstellar Boundary Explorer|IBEX]]
| 19 October 2008
| [[Pegasus XL]]
| 107
| MEO
| '''Operational'''
| In orbit
| SMEX: mapping the boundary between the Solar System and interstellar space.<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2008-051A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>

|-
! 92
| [[Wide-field Infrared Survey Explorer|WISE]]
| 14 December 2009
| [[Delta II]] 7320
| 661
| LEO 
| August 2024
| 2 November 2024
| MIDEX: infrared astronomy, NEOWISE extension. Discovered first [[Earth trojan]].<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2009-071A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>

|- style="background:#bfb;"
! style="background:#bfb;"| 93
| [[Nuclear Spectroscopic Telescope Array|NuSTAR]]
| 13 June 2012
| [[Pegasus XL]]
| 350
| LEO
| '''Operational'''
| In orbit
| SMEX: high-energy X-ray astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2012-031A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |date=2017-03-21 |access-date=2018-04-20}}</ref>

|- style="background:#bfb;"
! style="background:#bfb;"| 94
| [[Interface Region Imaging Spectrograph|IRIS]]
| 27 June 2013
| [[Pegasus XL]]
| 183
| [[Sun-synchronous orbit|SSO]]
| '''Operational'''
| In orbit
| SMEX: solar UV astronomy<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2013-033A |title=NASA - NSSDCA - Spacecraft - Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-20}}</ref>

|- 
! —
| [[Hitomi (satellite)|Hitomi]] (NeXT,  ASTRO-H)
| 7 February 2016
| [[H-2A]]-202
| 2,700
| LEO
| 26 March 2016
| In orbit
| MO: X-ray instrument on JAXA's Hitomi, but spacecraft failed after initial checkouts<ref>{{cite web|url=http://global.jaxa.jp/press/2016/03/20160327_hitomi.html |title=JAXA &#124; Communication anomaly of X-ray Astronomy Satellite "Hitomi" (ASTRO-H) |publisher=Global.jaxa.jp |access-date=2018-04-28}}</ref>

|- style="background:#bfb;"
! style="background:#bfb;"| —
| [[NICER]] 
| 3 May 2017
| [[Falcon 9]] FT
| 372
| [[ISS]]
| '''Operational'''
| ISS
| MO: instrument on ISS for [[neutron star]] observations

|- style="background:#bfb;"
! style="background:#bfb;"| —
| [[Global-scale Observations of the Limb and Disk|GOLD]] 
| 25 January 2018
| [[Ariane 5]] ECA
| 37
| [[Geostationary orbit|GEO]]
| '''Operational'''
| In orbit
| MO: instrument on [[SES-14]] comsat for studying Earth–space boundary

|- style="background:#bfb;"
! style="background:#bfb;"| 95
| [[Transiting Exoplanet Survey Satellite|TESS]]
| 18 April 2018
| [[Falcon 9]] FT
| 362
| HEO
| '''Operational'''
| In orbit
| MIDEX: survey for transiting exoplanets

|- style="background:#bfb;"
! style="background:#bfb;"| 96
| [[Ionospheric Connection Explorer|ICON]]
| 11 October 2019
| [[Pegasus (rocket)|Pegasus]] XL
| 287
| LEO
| '''Operational'''
| In orbit
| MIDEX: ionospheric studies

|- style="background:#bfb;"
! style="background:#bfb;"| 97
| [[IXPE]]
| 9 December 2021
| [[Falcon 9]] Block 5
| 330
| LEO
| '''Operational'''
| In orbit
| SMEX: X-ray studies

|- style="background:#bfb;"
! style="background:#bfb;"| —
| [[X-Ray Imaging and Spectroscopy Mission|XRISM]]
| 6 September 2023
| [[H-IIA]] 202
| 2,300
| LEO
| '''Operational'''
| In orbit
| MO: instruments on [[JAXA]]'s XRISM x-ray space telescope
|}