Thor-Ablestar

	The launch of a Thor-Ablestar 2 with a Transit satellite.
Function	Orbital carrier rocket
Manufacturer	Douglas / Aerojet
Country of origin	United States
Size
Height	29 metres (95 ft)
Diameter	2.44 metres (8 ft 0 in)
Mass	53,000 kilograms (117,000 lb)
Stages	2
Capacity
Payload to 1100km LEO
Mass	150 kilograms (330 lb)
Associated rockets
Family	Thor
Comparable	Delta
Launch history
Launch sites	LC-17, Canaveral; LC-75-1, Arguello
Total launches	19
Success(es)	12
Failure(s)	5
Partial failure(s)	2
First flight	13 April 1960
Last flight	13 August 1965
First stage – Thor
Powered by	1 MB-3-1
Maximum thrust	760.64 kilonewtons (171,000 lbf)
Specific impulse	285 sec
Burn time	164 seconds
Propellant	RP-1/LOX
Second stage – Ablestar
Powered by	1 AJ-10
Maximum thrust	36.02 kilonewtons (8,100 lbf)
Specific impulse	280 sec
Burn time	296 seconds
Propellant	HNO3/UDMH
	[edit on Wikidata]

The Thor-Ablestar, or Thor-Able-Star, also known as Thor-Epsilon ^[1] was an early American expendable launch system consisting of a PGM-17 Thor missile, with an Ablestar upper stage. It was a member of the Thor family of rockets, and was derived from the Thor-Able.

The Ablestar second stage was an enlarged version of the Able, which gave the Thor-Ablestar a greater payload capacity compared to the Thor-Able. It also incorporated restart capabilities, allowing a multiple-burn trajectory to be flown, further increasing payload, or allowing the rocket to reach different orbits. It was the first rocket to be developed with such a capability and development of the stage took a mere eight months.^[2]

Two versions were built; the Thor-Ablestar 1, with a DM-21 Thor and an AJ-10-104 second stage engine, and the Thor-Ablestar 2, which had a DSV-2A Thor first stage, and an uprated AJ-10-104D engine on the second stage.^[1] Thor-Ablestar 1 launches occurred from LC-17 at Cape Canaveral, and Thor-Ablestar 2 rockets were launched from LC-75-1 at Vandenberg Space Force Base (now designated SLC-2).

Launches

Nineteen Thor-Ablestar were launched between 1960 and 1965, of which four failed, and a fifth resulted in a partial failure, as only one of two payloads separated from the upper stage.^[2]

The first failure was the launch of Courier 1A, an experimental communications satellite, on 19 August 1960 when the first stage shut down 30 seconds earlier than planned and was destroyed by the Range Safety Officer.

On 30 November, another launch involving a Transit satellite failed in practically identical fashion. This episode nearly created an international incident as parts of the Thor landed in Cuba. War was threatened. Cuban leader Fidel Castro subsequently sold off the Thor's engine to the Soviets and the Chinese received its thrust vectors, which ended up proving valuable to the latter's development of a ballistic missile capability. To prevent this from happening again, future Thor Ablestar launches had their flight paths modified to avoid passing over Cuba.

The launch of a Transit satellite on 22 February 1961 was successful, but its companion Lofti satellite failed to separate from the second stage.

On 29 June 1961, a Thor-Ablestar successfully inserted a Transit-4A into orbit, but two hours later the Ablestar exploded for unknown reasons into hundreds of pieces, which remained in orbit. This is the first known artificial object to break up unintentionally in space.^[3]

The third launch failure occurred on 24 January 1962 when the second stage produced insufficient thrust to achieve orbital velocity for several piggybacked satellites.^[4] The fourth and final failure was the launch of an Anna geodetic satellite on 10 May 1962 when the second stage completely failed to ignite.

Date/Time (UTC)	S/N	Launch Site	Payload	Function	Outcome
1960-04-13 12:02:36	Thor 257 Ablestar 002	CCAFS LC-17B	Transit 1B	Navigation	Success, maiden flight of Thor-Ablestar
1960-06-22 05:54	Thor 281 Ablestar 003	CCAFS LC-17B	Transit 2A, GRAB-1 (Solrad 1)	Navigation, ELINT	Success
1960-08-18 19:58	Thor 262 Ablestar 004	CCAFS LC-17B	Courier 1A	Communications	Failure (Premature first stage cutoff. RSO T+150 seconds.)
1960-10-04 17:50	Thor 293 Ablestar 005	CCAFS LC-17B	Courier 1B	Communications	Success
1960-11-30 19:50	Thor 283 Ablestar 006	CCAFS LC-17B	Transit 3A, GRAB-2 (Solrad-2)	Navigation, ELINT	Failure (Premature Thor cutoff. RSO. Debris fell in Cuba.)
1961-02-22 03:45	Thor 313 Ablestar 007	CCAFS LC-17B	Transit 3B, LOFTI-1	Navigation, Technology	Success
1961-06-29 04:22	Thor 315 Ablestar 008	CCAFS LC-17B	Transit 4A, Injun 1, GRAB-3 (Solrad 3)	Navigation, Ionospheric, ELINT	Success
1961-11-15 22:26	Thor 305 Ablestar 009	CCAFS LC-17B	Transit 4B, TRAAC	Navigation	Success, Transit Research and Attitude Control
1962-01-24 09:30	Thor 311 Ablestar 010	CCAFS LC-17B	LOFTI-2, SECOR, GRAB-4 (Solrad 4), Injun 2, SURCAL 1	Technology, Geodesy, ELINT, Ionospheric, Calibration	Failure (second stage insufficient thrust)
1962-05-10 12:06	Thor 314 Ablestar 011	CCAFS LC-17B	ANNA 1A	Geodesy	Failure (second stage failed to ignite)
1962-10-31 08:08	Thor 319 Ablestar 012	CCAFS LC-17A	ANNA 1B	Geodesy	Success, final flight of Thor DM-21 Ablestar
1964-04-21 18:50	Thor 379 Ablestar 014	VAFB LC-75-1-1	Transit 5BN-3, Transit 5E-4	Navigation	Failure
1964-10-06 17:04:21	Thor 423 Ablestar 016	VAFB LC-75-1-2	OPS 5796 (Transit O-1), Dragsphere 1, Dragsphere 2	Navigation	Success
1964-12-13 00:08:10	Thor 427 Ablestar 017	VAFB LC-75-1-2	OPS 6582 (Transit O-2), Transit 5E-5	Navigation	Success
1965-03-11 13:39	Thor 440 Ablestar 018	VAFB LC-75-1-1	OPS 7087 (Transit O-3), SECOR 2	Navigation, Geodesy	Success
1965-06-24 22:35	Thor 447 Ablestar 019	VAFB LC-75-1-1	OPS 8480 (Transit O-4)	Navigation	Success
1965-08-13 22:11	Thor 455 Ablestar 020	VAFB LC-75-1-1	OPS 8464 (Transit O-5), Dodecapole 2, Tempsat 1, Surcal 5, Long Rod 1, Calsphere 2	Navigation, Calibration	Success, final flight of Thor-Ablestar

References

^ ^a ^b Krebs, Gunter. "Thor Able-Star". Gunter's Space Page. Retrieved 30 November 2008.
^ ^a ^b Wade, Mark. "Delta". Encyclopedia Astronautica. Archived from the original on 17 August 2013. Retrieved 30 November 2008.
^ Orbital Debris: A Chronology (PDF). NASA JSC. January 1999. p. 18. Archived from the original (PDF) on 1 September 2000. Retrieved 13 February 2016. Two hours after separating from the U.S. Transit 4-A satellite, its Able Star upper stage becomes the first known artificial object to break up unintentionally in space. The cause of the explosion is unknown. The event produces at least 294 trackable pieces, more than tripling the number of known satellites of Earth.
^ "A-Okay So Far: Glenn, Atlas Ready". The Gazette. Montreal, QC. Associated Press (AP). 25 January 1962. p. 1. Retrieved 29 December 2015.

[GSP-1] Krebs, Gunter. "Thor Able-Star". Gunter's Space Page. Retrieved 30 November 2008.

[EA-2] Wade, Mark. "Delta". Encyclopedia Astronautica. Archived from the original on 17 August 2013. Retrieved 30 November 2008.

[chronology-3] Orbital Debris: A Chronology (PDF). NASA JSC. January 1999. p. 18. Archived from the original (PDF) on 1 September 2000. Retrieved 13 February 2016. Two hours after separating from the U.S. Transit 4-A satellite, its Able Star upper stage becomes the first known artificial object to break up unintentionally in space. The cause of the explosion is unknown. The event produces at least 294 trackable pieces, more than tripling the number of known satellites of Earth.

[4] "A-Okay So Far: Glenn, Atlas Ready". The Gazette. Montreal, QC. Associated Press (AP). 25 January 1962. p. 1. Retrieved 29 December 2015.

[1]

[2]

[3]

[4]

v t e Orbital launch systems
List of orbital launch systems Comparison of orbital launch systems
Current	Angara 1.2 A5 Ariane 6 Atlas V Ceres 1 1S Chollima-1 Electron Falcon 9 Block 5 Falcon Heavy Firefly Alpha Gravity-1 GSLV H-IIA H3 Hyperbola-1 Jielong 1 3 KAIROS^† Kaituozhe 2 Kinetica 1 Kuaizhou 1 1A 11 Long March 2C 2D 2F 3A 3B/E 3C 4B 4C 5 5B 6 6A 7 7A 8 11 11H LVM3 Minotaur I IV V C Nuri OS-M1^† Pegasus XL Proton-M PSLV Qaem 100 Qased RS1^† Shavit 2 Simorgh SLS Block 1 Soyuz-2 2.1a / STA 2.1b / STB 2-1v SSLV Starship Tianlong-2 Unha Vega C Vulcan Centaur Zhuque 2
In development	Antares 330 Bloostar Cyclone-4M Deca Epsilon S Eris Gravity-2 Hyperbola-2 Irtysh Kuaizhou 21 31 Long March 9 10 12 Miura 5 MLV Neutron New Glenn New Line 1 NGLV Nova OS-M 2 4 Orbex Prime Pallas-1 Red Dwarf SLS Block 1B Block 2 Soyuz-7 Terran R Tianlong-3 VLM Vega E Zero Zhuque 3 Zuljanah
Retired	Antares 110 120 130^† 230 230+ Ariane 1 2 3 4 5 ASLV Athena I II Atlas B D E/F G H I II III LV-3B SLV-3 Able^† Agena Centaur Black Arrow Conestoga^† Delta A B C D E G J L M N 0100 1000 2000 3000 4000 5000 II III IV IV Heavy Diamant Dnepr Energia Epsilon Europa I^† II^† Falcon 1 Falcon 9 v1.0 v1.1 v1.2 "Full Thrust" Feng Bao 1 GSLV Mk I H-I H-II H-IIB Juno I Juno II Kaituozhe-1 Kosmos original 1 2/2I 3 3M Lambda 4S LauncherOne Long March 1 1D^† 2A 2E 3 3B 4A Mu 4S 3C 3H 3S 3SII V N1^† N-I N-II Naro-1 Paektusan^† Pilot-2^† R-7 Luna Molniya M L Polyot Soyuz original FG L M U U2 Soyuz/Vostok Sputnik Voskhod Vostok L K 2 2M R-29 Shtil' Volna^† Rocket 3 Safir 1 1A 1B Saturn I IB V Scout X-1 Blue Scout II^† X-2^† X-2M X-3 X-3M X-4 X-2B^† B A B-1 D-1 A-1 E-1 F-1 G-1 Shavit original 1 SLV Space Shuttle SPARK^† Sparta SS-520 Start-1 Terran 1^† Thor Able Ablestar 1 2 Agena A B D Burner 1 2 Delta DSV-2U Thorad-Agena SLV-2G SLV-2H Titan II GLV IIIA IIIB IIIC IIID IIIE 34D 23G CT-3 IV Tsyklon R-36-O original 2 3 Universal Rocket UR-500 Proton Proton-K Rokot Strela Vanguard Vega original VLS-1^† Zenit 2 2M 2FG 3SL 3SLB 3F Zhuque 1^†
Classes	Sounding rocket Small-lift launch vehicle Medium-lift launch vehicle Heavy-lift launch vehicle Super heavy-lift launch vehicle
This Template lists historical, current, and future space rockets that at least once attempted (but not necessarily succeeded in) an orbital launch or that are planned to attempt such a launch in the future Symbol ^† indicates past or current rockets that attempted orbital launches but never succeeded (never did or has yet to perform a successful orbital launch)

v t e Orbital launch systems developed in the United States
Active	Atlas V**^†† Electron Falcon 9 Block 5 Falcon Heavy Firefly Alpha Minotaur I IV V C Pegasus XL RS1^† SLS Block 1 Vulcan Centaur
In development	Antares 330 Daytona I MLV New Glenn Neutron Nova Red Dwarf SLS Block 1B Block 2 Starship Terran R
Retired	Antares 110/120/130/230/230+^††† Athena I II Atlas B D E/F G H I II III LV-3B SLV-3 Able Agena Centaur Conestoga Delta A B C D E G J L M N 0100 1000 2000 3000 4000 5000 II III IV IV Heavy Falcon 1 Falcon 9 v1.0 v1.1 v1.2 "Full Thrust" H-I* Juno I Juno II LauncherOne N-I* N-II* Pilot Rocket 3 Saturn I IB V Scout Space Shuttle SPARK Sparta Terran 1 Thor Able Ablestar Agena Burner Delta DSV-2U Thorad-Agena Titan II GLV IIIA IIIB IIIC IIID IIIE 34D 23G CT-3 IV Vanguard
* - Japanese projects using US rockets or stages ** - uses Russian engines ^† - never succeeded ^†† - no new orders accepted ^††† - used Ukrainian first stage

Launches

See also

References