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 +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 Remarks1957-01-26Thor DM-18Thor 101CCAFS LC-17BMissile testSuborbitalMaiden flight of Thor, first launch from LC-17. Contaminated LOX caused loss of thrust at liftoff. Vehicle fell back onto the pad and exploded.1957-04-2004:33Thor DM-18Thor 102CCAFS LC-17BMissile testSuborbitalRSO sent a mistaken destruct command at T+35 seconds due to an incorrect console readout.1957-08-30Thor DM-18Thor 104CCAFS LC-17AMissile testSuborbital1957-10-0317:14Thor DM-18Thor 107CCAFS LC-17AMissile testSuborbitalStuck valve prevented the gas generator from starting. Missile fell back onto the pad and exploded.1957-10-1116:33Thor DM-18Thor 108CCAFS LC-17BMissile testSuborbitalTurbopump failure at T+152 seconds. Flight considered a "partial success". 1960-1969 Date/Time(UTC)RocketS/NLaunch sitePayloadFunctionOrbitOutcomeRemarks 1960-02-0418:51:45 Thor DM-18 Agena-A Thor 218 VAFB LC-75-3-4 Discoverer 9 Reconnaissance LEO Premature Thor cutoff. Agena could not attain orbital velocity. 1960-02-1920:15:14 Thor DM-18 Agena-A Thor 223Agena 1054 VAFB LC-75-3-5 Discoverer 10 Reconnaissance LEO Thor flight control malfunction. RSO T+52 seconds. 1960-05-1309:16:05 Thor DM-19 Delta Thor 144Delta 1 CCAFS LC-17A Echo 1 Communication MEO Maiden flight of Thor-Delta, upper-stage attitude control system malfunctioned 1960-06-2922:00:44 Thor DM-18 Agena-A Thor 160Agena 1053 VAFB LC-75-3-4 Discoverer 12 Reconnaissance LEO Agena attitude control malfunction. 1960-08-1819:58 Thor DM-21 Ablestar Thor 262Ablestar 004 CCAFS LC-17B Courier 1A Communications LEO Premature first stage cutoff. RSO T+150 seconds. 1960-10-2620:26 Thor DM-21 Agena-B Thor 253Agena 1061 VAFB LC-75-3-4 Discoverer 16 Reconnaissance LEO Maiden flight of Thor-Agena B. Agena staging failed. Vehicle fell into the Pacific Ocean. 1960-11-3019:50 Thor DM-21 Ablestar Thor 283Ablestar 006 CCAFS LC-17B Transit 3AGRAB-2 (Solrad-2) NavigationELINT LEO Premature Thor cutoff. RSO. Debris fell in Cuba. 1961-03-3020:34:43 Thor DM-21 Agena-B Thor 300Agena 1105 VAFB LC-75-3-4 Discoverer 22 Reconnaissance LEO Agena control failure. 1961-06-0821:16 Thor DM-21 Agena-B Thor 302Agena 1108 VAFB LC-75-3-4 Discoverer 24 Reconnaissance LEO Agena power failure 1961-07-2122:35 Thor DM-21 Agena-B Thor 322Agena 1110 VAFB LC-75-3-4 Discoverer 27 Reconnaissance LEO Open circuit in guidance computer led to loss of control and vehicle breakup at T+60 seconds. 1961-08-0400:01 Thor DM-21 Agena-B Thor 309Agena 1111 VAFB LC-75-1-1 Discoverer 28 Reconnaissance LEO Agena control system malfunctioned 1961-10-2319:23 Thor DM-21 Agena-B Thor 329Agena 1116 VAFB LC-75-3-5 Discoverer 33 Reconnaissance LEO Agena hydraulics failure 1961-11-0520:00 Thor DM-21 Agena-B Thor 330Agena 1117 VAFB LC-75-1-1 Discoverer 34 Reconnaissance LEO Incorrect guidance program left the satellite in a useless orbit. 1962-01-1321:41 Thor DM-21 Agena-B Thor 327Agena 1120 VAFB LC-75-3-4 Discoverer 37 Reconnaissance LEO Agena restart burn failed. 1962-01-2409:30 Thor DM-21 Ablestar Thor 311Ablestar 010 CCAFS LC-17B LOFTI-2ASECORGRAB-4 (Solrad 4)Injun 2SURCAL 1 TechnologyGeodesyELINTIonosphericCalibration LEO Second stage insufficient thrust 1962-02-2118:44 Thor DM-21 Agena-B Thor 332Agena 2301 VAFB LC-75-3-5 FTV 2301 ELINT LEO Upper stage failed to restart for circularization burn 1962-05-1012:06 Thor DM-21 Ablestar Thor 314Ablestar 011 CCAFS LC-17B ANNA 1A Geodesy LEO Second stage failed to ignite 1962-06-0409:44:17 Thor DSV-2E Thor 199 Johnston LE-1 Bluegill Nuclear test Suborbital Radar contact lost 5 minutes after launch. RSO destruct command sent. 1962-06-2008:46:16 Thor DSV-2E Thor 193 Johnston LE-1 STARFISH Nuclear test Suborbital 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. 1962-07-2609:13:53 Thor DSV-2E Thor 180 Johnston LE-1 Bluegill Prime Nuclear test Suborbital 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 09:14:38Thor DSV-2EThor 156Johnston LE-2Bluegill Double PrimeNuclear testSuborbital Flight control failure T+85 seconds. RSO T+156 seconds. 1963-02-2821:48 TAT SLV-2A Agena-D Thor 354Agena 1159 VAFB LC-75-3-5 OPS 0583 Reconnaissance LEO 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. 1963-03-1821:13 TAT SLV-2A Agena-D Thor 360Agena 1164 VAFB LC-75-3-4 OPS 0627 Reconnaissance LEO Electrical short at staging causes loss of Agena control and no orbit. 1963-04-2620:13 Thor DM-21 Agena-D Thor 372Agena 1411 VAFB LC-75-1-1 OPS 1008 Reconnaissance LEO Attitude sensor alignment error results in no Agena orbit. 1963-11-0920:27:54 Thor SLV-2 Agena-D Thor 400Agena 1171 VAFB LC-75-1-2 OPS 2268 Reconnaissance LEO Loss of heat shield causes high thrust section temperatures. Control loss at T+113 seconds followed by propulsion system shutdown. 1964-03-1911:13:41 Delta B Thor 391Delta 24 CCAFS LC-17A BE-A Ionospheric LEO Third stage underperformed 1964-03-2412:15 Thor DSV-2G Thor 240 CCAFS LC-17B ASSET-2 REV test Suborbital Atmospheric flight, second stage fired intermittently, destroyed by range safety 1964-03-2422:22:48 TAT SLV-2A Agena-D Thor 396Agena 1175 Arguello LC-1-1 OPS 3467 Reconnaissance LEO Agena power failure. No orbit. 1964-04-2118:50 Thor DSV-2A Ablestar Thor 379Ablestar 014 VAFB LC-75-1-1 Transit 5BN-3Transit 5E-4 Navigation LEO 1964-05-2807:32 Thor DSV-2J Thor 227 Johnston LE-2 ASAT test Suborbital 1964-08-2807:56:57 Thor SLV-2 Agena-B Thor 399Agena 6201TA-3 VAFB LC-75-1-1 Nimbus 1 Weather LEO Second-stage cutoff early during second burn 1964-10-0403:45:00 Delta C Thor 392Delta 26 CCAFS LC-17A Explorer 21 Magnetospheric HEO Reached lower than planned orbit 1965-01-1905:03 Thor MG-18 Thor 224 VAFB SLC-10W DMSP-3B-F1 Military weather satellite planned: LEO / SSO 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. 1965-09-0220:00 Thor DM-21 Agena-D Thor 401Agena 1602 VAFB LC-75-3-5 MPRV Upper atmosphere and space experiments planned: MEO High winds caused the vehicle to drift off course. RSO T+43 seconds. Debris fell on a trailer park. 1966-01-0804:48 Thor Burner 1 Thor 251 VAFB SLC-10W DMSP-3B-F5 Military weather satellite planned: LEO / SSO FW-4S second-stage motor failed to ignite. 1966-05-0319:25 TAT SLV-2A Agena-D Thor 465Agena 1625 VAFB LC-75-3-5 OPS 1508 (KH-4A #1032) Reconnaissance planned: LEO Agena failed to separate from the Thor at staging. Vehicle fell into the Pacific Ocean. 1967-05-0921:50 Thorad SLV-2G Agena-D Thor 508Agena 1634 VAFB SLC-1E KH-4A (S/N 1041)/SRV S/N 731 Reconnaissance planned: LEO Rocket failed to cut off, resulting in incorrect, but usable orbit 1968-05-1808:23 Thorad SLV-2G Agena-D Thor 520Agena 6221 VAFB SLC-2E Nimbus B/EGRS-10 Weather Satellite / Geodesic research satellite planned: LEO / SSO Incorrectly installed yaw gyro led to loss of control. RSO T+101 seconds. 1968-09-1900:09 Delta M Thor 529Delta 59 CCAFS SLC-17A Intelsat 3-1 Communication Satellite planned: GTO Pitch gyroscope failure led to loss of control starting at T+20 seconds. RSO T+110 seconds. 1969-07-2602:06 Delta M Thor 547Delta 71 CCAFS SLC-17A Intelsat 3-5 Communication Satellite planned: GTO Stage 3 motor case ruptured, leaving spacecraft in unusable orbit 1969-08-2721:59 Delta L Thor 540Delta 73 CCAFS LC-17A Pioneer E / TTS-3 Interplanetary space research probe / Technology demonstration satellite planned: Heliocentric 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)RocketS/NLaunch sitePayloadFunctionOrbitOutcomeRemarks 1970-04-24 Thor DSV-2J Thor 225 Johnston LE-1 Satellite Inspection test Suborbital Thor rocket collided with the satellite. 1971-02-1720:04 Thorad SLV-2H Agena-D Thor 537Agena 1659 VAFB SLC-3W KH-4B (S/N 1113) Reconnaissance LEO 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. 1971-10-2111:32 Delta N6 Delta 86Thor 572 VAFB SLC-2E ITOS-B Weather Satellite planned: LEO / SSO 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. 1973-07-1617:10 Delta 300 Delta 96Thor 578 VAFB SLC-2W ITOS-E Weather Satellite planned: LEO / SSO Hydraulic pump malfunction led to failure of the 2nd stage attitude control system. The booster and payload reentered the atmosphere and broke up. 1974-01-1901:38 Delta 2313 Delta 100Thor 587 CCAFS SLC-17B Skynet-2A Military communication satellite planned: GTO 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. 1976-02-1907:52 Thor Burner 2A Thor 182 VAFB SLC-10W DMSP-5C-F3 Military weather satellite planned: LEO / SSO Thor stage not loaded with enough kerosene fuel due to incorrect LR79 main engine data sheet entry. Satellite re-entered after one orbit. 1977-04-2010:15 Delta 2914 Delta 130Thor 617 CCAFS SLC-17B ESA-GEOS-1 Magnetosphere research satellite planned: GTO Premature separation of second and third stages led to failure of Stage 3 spin up. 1977-09-1323:21 Delta 3914 Delta 134Thor 619 CCAFS SLC-17A OTS-1 Experimental communication satellite planned: GTO Launch vehicle exploded at T+52 seconds due to a rupture of the SRM #1 casing. 1979-02-0608:46 N-I N-5 (F) Tanegashima SLC-N ECS-A (Ayame 1) Experimental communication satellite planned: GTO Recontact between satellite and upper stage. 1980-1989 Date/Time (UTC)RocketS/NLaunch sitePayloadFunctionOrbitOutcomeRemarks 1980-07-1502:22 Thor DSV-2U Thor 304 VAFB SLC-10W DMSP-5D-F5 Military weather satellite planned: LEO / SSO 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. 1986-05-0322:18 Delta 3914 178 CCAFS LC-17A GOES-G Weather Satellite planned: GTO Electric failure in first stage caused the rocket to lose control and was destroyed 90 seconds into flight 1990-1999 Date / time (UTC)Rocket