List of failed Thor and Delta launches

This is a list of failed launches of rockets in the Thor and Delta rocket family.

The Thor and Delta family rockets have had 51 complete failures, 10 partial failures, and 1 partial success, for a total of 62 unsuccessful Thor and Delta family missions. Since it has had 768 launches, this gives it a reliability of 91.9%, which puts it within the average range for rockets that started around the space age.

Launch attempts
{| class="wikitable sortable mw-collapsible" style="margin: 1em 1em 1em 0" ! colspan="9" |
 * +The data in this table comes from          in addition to the references listed within the table.

1957-1959
! Date/Time (UTC) ! Rocket ! S/N ! Launch Site ! Payload ! Function ! Orbit ! Outcome ! Remarks 04:33 17:14 16:33 ! colspan="9" |
 * 1957-01-26
 * Thor DM-18
 * Thor 101
 * CCAFS LC-17B
 * Missile test
 * Suborbital
 * Failure
 * Maiden flight of Thor, first launch from LC-17. Contaminated LOX caused loss of thrust at liftoff. Vehicle fell back onto the pad and exploded.
 * 1957-04-20
 * Failure
 * Maiden flight of Thor, first launch from LC-17. Contaminated LOX caused loss of thrust at liftoff. Vehicle fell back onto the pad and exploded.
 * 1957-04-20
 * 1957-04-20
 * Thor DM-18
 * Thor 102
 * CCAFS LC-17B
 * Missile test
 * Suborbital
 * Failure
 * RSO sent a mistaken destruct command at T+35 seconds due to an incorrect console readout.
 * 1957-08-30
 * Thor DM-18
 * Thor 104
 * CCAFS LC-17A
 * Missile test
 * Suborbital
 * Failure
 * 1957-10-03
 * Suborbital
 * Failure
 * 1957-10-03
 * 1957-10-03
 * 1957-10-03
 * Thor DM-18
 * Thor 107
 * CCAFS LC-17A
 * Missile test
 * Suborbital
 * Failure
 * Stuck valve prevented the gas generator from starting. Missile fell back onto the pad and exploded.
 * 1957-10-11
 * 1957-10-11
 * 1957-10-11
 * Thor DM-18
 * Thor 108
 * CCAFS LC-17B
 * Missile test
 * Suborbital
 * Partial success
 * Turbopump failure at T+152 seconds. Flight considered a "partial success".
 * Turbopump failure at T+152 seconds. Flight considered a "partial success".

1960-1969
!Date/Time (UTC) !Rocket !S/N !Launch Site !Payload !Function !Orbit !Outcome !Remarks 18:51:45 Agena 1052 20:15:14 Agena 1054 09:16:05 Delta 1 22:00:44 Agena 1053 19:58 Ablestar 004 20:26 Agena 1061 19:50 Ablestar 006 GRAB-2 (Solrad-2) ELINT 20:34:43 Agena 1105 21:16 Agena 1108 22:35 Agena 1110 00:01 Agena 1111 19:23 Agena 1116 20:00 Agena 1117 21:41 Agena 1120 09:30 Ablestar 010 SECOR GRAB-4 (Solrad 4) Injun 2 SURCAL 1 Geodesy ELINT Ionospheric Calibration 18:44 Agena 2301 12:06 Ablestar 011 09:44:17 08:46:16 09:13:53 09:14:38 21:48 Agena 1159 21:13 Agena 1164 20:13 Agena 1411 20:27:54 Agena 1171 11:13:41 Delta 24 12:15 22:22:48 Agena 1175 18:50 Ablestar 014 Transit 5E-4 07:32 07:56:57 Agena 6201 TA-3 03:45:00 Delta 26 05:03 20:00 Agena 1602 04:48 19:25 Agena 1625 21:50 Agena 1634 08:23 Agena 6221 00:09 Delta 59 02:06 Delta 71 21:59 Delta 73 ! colspan="9" |
 * 1960-02-04
 * 1960-02-04
 * Thor DM-18 Agena-A
 * Thor 218
 * VAFB LC-75-3-4
 * Discoverer 9
 * Reconnaissance
 * LEO
 * Failure
 * Premature Thor cutoff. Agena could not attain orbital velocity.
 * 1960-02-19
 * 1960-02-19
 * Thor DM-18 Agena-A
 * Thor 223
 * VAFB LC-75-3-5
 * Discoverer 10
 * Reconnaissance
 * LEO
 * Failure
 * Thor flight control malfunction. RSO T+52 seconds.
 * 1960-05-13
 * 1960-05-13
 * Thor DM-19 Delta
 * Thor 144
 * CCAFS LC-17A
 * Echo 1
 * Communication
 * MEO
 * Failure
 * Maiden flight of Thor-Delta, upper-stage attitude control system malfunctioned
 * 1960-06-29
 * 1960-06-29
 * Thor DM-18 Agena-A
 * Thor 160
 * VAFB LC-75-3-4
 * Discoverer 12
 * Reconnaissance
 * LEO
 * Failure
 * Agena attitude control malfunction.
 * 1960-08-18
 * 1960-08-18
 * Thor DM-21 Ablestar
 * Thor 262
 * CCAFS LC-17B
 * Courier 1A
 * Communications
 * LEO
 * Failure
 * Premature first stage cutoff. RSO T+150 seconds.
 * 1960-10-26
 * 1960-10-26
 * Thor DM-21 Agena-B
 * Thor 253
 * VAFB LC-75-3-4
 * Discoverer 16
 * Reconnaissance
 * LEO
 * Failure
 * Maiden flight of Thor-Agena B. Agena staging failed. Vehicle fell into the Pacific Ocean.
 * 1960-11-30
 * 1960-11-30
 * Thor DM-21 Ablestar
 * Thor 283
 * CCAFS LC-17B
 * Transit 3A
 * Navigation
 * LEO
 * Failure
 * Premature Thor cutoff. RSO. Debris fell in Cuba.
 * 1961-03-30
 * 1961-03-30
 * Thor DM-21 Agena-B
 * Thor 300
 * VAFB LC-75-3-4
 * Discoverer 22
 * Reconnaissance
 * LEO
 * Failure
 * Agena control failure.
 * 1961-06-08
 * 1961-06-08
 * Thor DM-21 Agena-B
 * Thor 302
 * VAFB LC-75-3-4
 * Discoverer 24
 * Reconnaissance
 * LEO
 * Failure
 * Agena power failure
 * 1961-07-21
 * 1961-07-21
 * Thor DM-21 Agena-B
 * Thor 322
 * VAFB LC-75-3-4
 * Discoverer 27
 * Reconnaissance
 * LEO
 * Failure
 * Open circuit in guidance computer led to loss of control and vehicle breakup at T+60 seconds.
 * 1961-08-04
 * 1961-08-04
 * Thor DM-21 Agena-B
 * Thor 309
 * VAFB LC-75-1-1
 * Discoverer 28
 * Reconnaissance
 * LEO
 * Failure
 * Agena control system malfunctioned
 * 1961-10-23
 * 1961-10-23
 * Thor DM-21 Agena-B
 * Thor 329
 * VAFB LC-75-3-5
 * Discoverer 33
 * Reconnaissance
 * LEO
 * Failure
 * Agena hydraulics failure
 * 1961-11-05
 * 1961-11-05
 * Thor DM-21 Agena-B
 * Thor 330
 * VAFB LC-75-1-1
 * Discoverer 34
 * Reconnaissance
 * LEO
 * Failure
 * Incorrect guidance program left the satellite in a useless orbit.
 * 1962-01-13
 * 1962-01-13
 * Thor DM-21 Agena-B
 * Thor 327
 * VAFB LC-75-3-4
 * Discoverer 37
 * Reconnaissance
 * LEO
 * Failure
 * Agena restart burn failed.
 * 1962-01-24
 * 1962-01-24
 * Thor DM-21 Ablestar
 * Thor 311
 * CCAFS LC-17B
 * LOFTI-2A
 * Technology
 * LEO
 * Failure
 * Second stage insufficient thrust
 * 1962-02-21
 * 1962-02-21
 * Thor DM-21 Agena-B
 * Thor 332
 * VAFB LC-75-3-5
 * FTV 2301
 * ELINT
 * LEO
 * Partial failure
 * Upper stage failed to restart for circularization burn
 * 1962-05-10
 * 1962-05-10
 * Thor DM-21 Ablestar
 * Thor 314
 * CCAFS LC-17B
 * ANNA 1A
 * Geodesy
 * LEO
 * Failure
 * Second stage failed to ignite
 * 1962-06-04
 * 1962-06-04
 * Thor DSV-2E
 * Thor 199
 * Johnston LE-1
 * Bluegill
 * Nuclear test
 * Suborbital
 * Failure
 * Radar contact lost 5 minutes after launch. RSO destruct command sent.
 * 1962-06-20
 * 1962-06-20
 * Thor DSV-2E
 * Thor 193
 * Johnston LE-1
 * STARFISH
 * Nuclear test
 * Suborbital
 * Failure
 * RVs caused turbine exhaust gas to enter the thrust section, overheating and weakening the engine mounts. Engine broke loose and ruptured the propellant tanks T+59 seconds. Warhead destroyed by RSO T+65 seconds.
 * 1962-07-26
 * 1962-07-26
 * Thor DSV-2E
 * Thor 180
 * Johnston LE-1
 * Bluegill Prime
 * Nuclear test
 * Suborbital
 * Failure
 * Stuck LOX valve caused loss of thrust and fire on the launch stand. Range Safety Officer destroyed the missile and warhead. Launch area extensively contaminated with plutonium.
 * 1962-10-16
 * 1962-10-16
 * Thor DSV-2E
 * Thor 156
 * Johnston LE-2
 * Bluegill Double Prime
 * Nuclear test
 * Suborbital
 * Failure
 * Flight control failure T+85 seconds. RSO T+156 seconds.
 * 1963-02-28
 * 1963-02-28
 * TAT SLV-2A Agena-D
 * Thor 354
 * VAFB LC-75-3-5
 * OPS 0583
 * Reconnaissance
 * LEO
 * Failure
 * Maiden flight of Thrust-Augmented Thor Agena. One SRB failed to ignite and subsequently separate from the vehicle, resulting in loss of control and self-destruct T+127 seconds.
 * 1963-03-18
 * 1963-03-18
 * TAT SLV-2A Agena-D
 * Thor 360
 * VAFB LC-75-3-4
 * OPS 0627
 * Reconnaissance
 * LEO
 * Failure
 * Electrical short at staging causes loss of Agena control and no orbit.
 * 1963-04-26
 * 1963-04-26
 * Thor DM-21 Agena-D
 * Thor 372
 * VAFB LC-75-1-1
 * OPS 1008
 * Reconnaissance
 * LEO
 * Failure
 * Attitude sensor alignment error results in no Agena orbit.
 * 1963-11-09
 * 1963-11-09
 * Thor SLV-2 Agena-D
 * Thor 400
 * VAFB LC-75-1-2
 * OPS 2268
 * Reconnaissance
 * LEO
 * Failure
 * Loss of heat shield causes high thrust section temperatures. Control loss at T+113 seconds followed by propulsion system shutdown.
 * 1964-03-19
 * 1964-03-19
 * Delta B
 * Thor 391
 * CCAFS LC-17A
 * BE-A
 * Ionospheric
 * LEO
 * Failure
 * Third stage underperformed
 * 1964-03-24
 * 1964-03-24
 * Thor DSV-2G
 * Thor 240
 * CCAFS LC-17B
 * ASSET-2
 * REV test
 * Suborbital
 * Failure
 * Atmospheric flight, second stage fired intermittently, destroyed by range safety
 * 1964-03-24
 * 1964-03-24
 * TAT SLV-2A Agena-D
 * Thor 396
 * Arguello LC-1-1
 * OPS 3467
 * Reconnaissance
 * LEO
 * Failure
 * Agena power failure. No orbit.
 * 1964-04-21
 * 1964-04-21
 * Thor DSV-2A Ablestar
 * Thor 379
 * VAFB LC-75-1-1
 * Transit 5BN-3
 * Navigation
 * LEO
 * Failure
 * 1964-05-28
 * 1964-05-28
 * 1964-05-28
 * Thor DSV-2J
 * Thor 227
 * Johnston LE-2
 * ASAT test
 * Suborbital
 * Failure
 * 1964-08-28
 * 1964-08-28
 * 1964-08-28
 * 1964-08-28
 * Thor SLV-2 Agena-B
 * Thor 399
 * VAFB LC-75-1-1
 * Nimbus 1
 * Weather
 * LEO
 * Partial failure
 * Second-stage cutoff early during second burn
 * 1964-10-04
 * 1964-10-04
 * Delta C
 * Thor 392
 * CCAFS LC-17A
 * Explorer 21
 * Magnetospheric
 * HEO
 * Partial failure
 * Reached lower than planned orbit
 * 1965-01-19
 * 1965-01-19
 * Thor MG-18
 * Thor 224
 * VAFB SLC-10W
 * DMSP-3B-F1
 * Military weather satellite
 * planned: LEO / SSO
 * Partial failure
 * Maiden flight of the Thor-Burner series. Satellite failed to separate from the upper stage, but the satellite was able to operate for 6 months.
 * 1965-09-02
 * 1965-09-02
 * Thor DM-21 Agena-D
 * Thor 401
 * VAFB LC-75-3-5
 * MPRV
 * Upper atmosphere and space experiments
 * planned: MEO
 * Failure
 * High winds caused the vehicle to drift off course. RSO T+43 seconds. Debris fell on a trailer park.
 * 1966-01-08
 * 1966-01-08
 * Thor Burner 1
 * Thor 251
 * VAFB SLC-10W
 * DMSP-3B-F5
 * Military weather satellite
 * planned: LEO / SSO
 * Failure
 * FW-4S second-stage motor failed to ignite.
 * 1966-05-03
 * 1966-05-03
 * TAT SLV-2A Agena-D
 * Thor 465
 * VAFB LC-75-3-5
 * OPS 1508 (KH-4A #1032)
 * Reconnaissance
 * planned: LEO
 * Failure
 * Agena failed to separate from the Thor at staging. Vehicle fell into the Pacific Ocean.
 * 1967-05-09
 * 1967-05-09
 * Thorad SLV-2G Agena-D
 * Thor 508
 * VAFB SLC-1E
 * KH-4A (S/N 1041)/SRV S/N 731
 * Reconnaissance
 * planned: LEO
 * Partial failure
 * Rocket failed to cut off, resulting in incorrect, but usable orbit
 * 1968-05-18
 * 1968-05-18
 * Thorad SLV-2G Agena-D
 * Thor 520
 * VAFB SLC-2E
 * Nimbus B/EGRS-10
 * Weather Satellite / Geodesic research satellite
 * planned: LEO / SSO
 * Failure
 * Incorrectly installed yaw gyro led to loss of control. RSO T+101 seconds.
 * 1968-09-19
 * 1968-09-19
 * Delta M
 * Thor 529
 * CCAFS SLC-17A
 * Intelsat 3-1
 * Communication Satellite
 * planned: GTO
 * Failure
 * Pitch gyroscope failure led to loss of control starting at T+20 seconds. RSO T+110 seconds.
 * 1969-07-26
 * 1969-07-26
 * Delta M
 * Thor 547
 * CCAFS SLC-17A
 * Intelsat 3-5
 * Communication Satellite
 * planned: GTO
 * Partial failure
 * Stage 3 motor case ruptured, leaving spacecraft in unusable orbit
 * 1969-08-27
 * 1969-08-27
 * Delta L
 * Thor 540
 * CCAFS LC-17A
 * Pioneer E / TTS-3
 * Interplanetary space research probe / Technology demonstration satellite
 * planned: Heliocentric
 * Failure
 * Defective valve in Stage 1 caused a hydraulic fluid leak and loss of engine gimbaling at T+220 seconds, making it impossible for the second stage to reach orbit. RSO T+480 seconds.

1970-1979
!Date/Time (UTC) !Rocket !S/N !Launch Site !Payload !Function !Orbit !Outcome !Remarks 20:04 Agena 1659 11:32 Thor 572 17:10 Thor 578 01:38 Thor 587 07:52 10:15 Thor 617 23:21 Thor 619 08:46 ! colspan="9" |
 * 1970-04-24
 * Thor DSV-2J
 * Thor 225
 * Johnston LE-1
 * Satellite Inspection test
 * Suborbital
 * Failure
 * Thor rocket collided with the satellite.
 * 1971-02-17
 * Thor rocket collided with the satellite.
 * 1971-02-17
 * 1971-02-17
 * Thorad SLV-2H Agena-D
 * Thor 537
 * VAFB SLC-3W
 * KH-4B (S/N 1113)
 * Reconnaissance
 * LEO
 * Failure
 * Improper pre-flight procedure caused frozen lubricant to form a plug that resulted in complete turbopump failure 18 seconds after liftoff. The booster lost thrust and impacted the ground not far from the launch complex.
 * 1971-10-21
 * 1971-10-21
 * Delta N6
 * Delta 86
 * VAFB SLC-2E
 * ITOS-B
 * Weather Satellite
 * planned: LEO / SSO
 * Failure
 * 2nd stage oxidizer leak starting at T+20 seconds. The attitude control system ran out of propellant trying to correct the stage's flight path and the launch vehicle reentered the atmosphere and broke up above the Arctic Circle.
 * 1973-07-16
 * 1973-07-16
 * Delta 300
 * Delta 96
 * VAFB SLC-2W
 * ITOS-E
 * Weather Satellite
 * planned: LEO / SSO
 * Failure
 * Hydraulic pump malfunction led to failure of the 2nd stage attitude control system. The booster and payload reentered the atmosphere and broke up.
 * 1974-01-19
 * 1974-01-19
 * Delta 2313
 * Delta 100
 * CCAFS SLC-17B
 * Skynet-2A
 * Military communication satellite
 * planned: GTO
 * Failure
 * First flight of the Delta 2000 series. Stage 2 electronics package short circuited (induced by a piece of conductive contaminant shaken loose during launch), leading to loss of control.
 * 1976-02-19
 * 1976-02-19
 * Thor Burner 2A
 * Thor 182
 * VAFB SLC-10W
 * DMSP-5C-F3
 * Military weather satellite
 * planned: LEO / SSO
 * Failure
 * Thor stage not loaded with enough kerosene fuel due to incorrect LR79 main engine data sheet entry. Satellite re-entered after one orbit.
 * 1977-04-20
 * 1977-04-20
 * Delta 2914
 * Delta 130
 * CCAFS SLC-17B
 * ESA-GEOS-1
 * Magnetosphere research satellite
 * planned: GTO
 * Partial failure
 * Premature separation of second and third stages led to failure of Stage 3 spin up.
 * 1977-09-13
 * 1977-09-13
 * Delta 3914
 * Delta 134
 * CCAFS SLC-17A
 * OTS-1
 * Experimental communication satellite
 * planned: GTO
 * Failure
 * Launch vehicle exploded at T+52 seconds due to a rupture of the SRM #1 casing.
 * 1979-02-06
 * 1979-02-06
 * N-I
 * N-5 (F)
 * Tanegashima SLC-N
 * ECS-A (Ayame 1)
 * Experimental communication satellite
 * planned: GTO
 * Failure
 * Recontact between satellite and upper stage.

1980-1989
!Date/Time (UTC) !Rocket !S/N !Launch Site !Payload !Function !Orbit !Outcome !Remarks 02:22 ! colspan="9" |
 * 1980-07-15
 * 1980-07-15
 * Thor DSV-2U
 * Thor 304
 * VAFB SLC-10W
 * DMSP-5D-F5
 * Military weather satellite
 * planned: LEO / SSO
 * Failure
 * Final flight of the Long Tank Thor. Failure attributed to faulty connection between second and third stages, resulting in third stage not receiving electrical power.
 * 1986-05-03 22:18
 * Delta 3914
 * 178
 * CCAFS LC-17A
 * GOES-G
 * Weather Satellite
 * planned: GTO
 * Failure
 * Electric failure in first stage caused the rocket to lose control and was destroyed 90 seconds into flight
 * Electric failure in first stage caused the rocket to lose control and was destroyed 90 seconds into flight

1990-1999
!Date / time (UTC) !Rocket Configuration !Launch site !Payload !Payload mass !Orbit !Customer !Outcome !Remarks 01:17 01:00 ! colspan="9" |
 * 5 August 1995 11:10
 * Delta II 7925–9.5
 * CCAFS, LC-17B
 * Koreasat 1
 * 711 kg
 * GTO
 * KT Corporation
 * Partial failure
 * Communications satellite, One SRB failed to separate, retarding the booster's orbital velocity. Spacecraft eventually reached correct orbit but with substantially shortened operational life.
 * January 17, 1997 16:28
 * Delta II 7925–9.5
 * CCAFS LC-17A
 * GPS IIR-1
 * 2,030 kg
 * Planned: MEO
 * US Air Force
 * Failure
 * Exploded 13 seconds after launch due to SRB failure. Navigation satellite
 * August 27, 1998
 * Exploded 13 seconds after launch due to SRB failure. Navigation satellite
 * August 27, 1998
 * August 27, 1998
 * Delta III 8930
 * CCAFS SLC-17B
 * Galaxy 10
 * 700 kg
 * GTO
 * PanAmSat / Intelsat
 * Failure
 * Maiden flight of Delta III, Destroyed by range safety after control problems and depletion of hydraulic fluid, Communications satellite
 * May 5, 1999
 * May 5, 1999
 * Delta III 8930
 * CCAFS SLC-17B
 * Orion 3
 * 4,300 kg
 * GTO
 * Loral
 * Failure
 * Second stage engine failure. Payload placed into LEO, Communications satellite

Since 2000
! scope="col" | Date / time (UTC) ! scope="col" | Rocket, Configuration ! scope="col" | Launch site ! scope="col" | Payload ! scope="col" | Payload mass ! scope="col" | Orbit ! scope="col" | Customer ! scope="col" | Launch outcome ! scope="col" |Remarks 11:05 21:50
 * August 23, 2000
 * August 23, 2000
 * Delta III 8930
 * CCAFS SLC-17B
 * DM-F3
 * 4383 kg
 * GTO
 * US Air Force
 * Partial failure
 * Reached lower than planned orbit, final flight of Delta III, Demosat
 * December 21, 2004
 * December 21, 2004
 * Delta IV Heavy
 * CCAFS SLC-37B
 * DemoSat / 3CS-1 / 3CS-2
 * >6020 kg
 * GSO (planned)
 * Partial failure
 * Demonstration payload, Payloads did not reach correct orbits, First Delta IV Heavy launch
 * }
 * }
 * }