Thor-Ablestar

	The launch of a Thor-Ablestar 2 with a Transit satellite.
Function	Orbital carrier rocket
P176	Douglas / Aerojet
P495	United States
Size
P2048	29 metres (95 ft)
P2386	2.44 metres (8 ft 0 in)
P2067	53,000 kilograms (117,000 lb)
Stages	2
Capacity
Payload to 1100km LEO
P2067	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
P516	1 MB-3-1
P2228	760.64 kilonewtons (171,000 lbf)
Specific impulse	285 sec
Burn time	164 seconds
Propellant	RP-1/LOX
Second stage – Ablestar
P516	1 AJ-10
P2228	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]

Nineteen Thor-Ablestar were launched between 1960–1965, 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.^[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.

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 and is now designated SLC-2.

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.

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[2]

[3]

[4]

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In development	Amur Antares 330 Ariane 6 Bloostar Cyclone-4M Eris Firefly Beta H3 Hyperbola-2 Irtysh Kuaizhou 21 31 Long March 921 rocket 9 Miura 5 Neutron New Glenn New Line 1 OS-M 2 4 Orbex Prime Pallas-1 Red Dwarf SLS Block 1 Block 1B Block 2 Soyuz-7 Starship Terran 1 R Vega E Vulcan Zero Zhuque-2 Zuljanah
Retired	Antares 110 120 130^† 230 Ariane 1 2 3 4 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 Diamant Dnepr Energia Europa^† 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 Kuaizhou 11^† Lambda 4S 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 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 original 2 3 Universal Rocket UR-500 Proton Proton-K Rokot Strela Vanguard VLS-1^† Zenit 2 2M
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	Antares 230+ Atlas V Delta IV Heavy Falcon 9 Block 5 Falcon Heavy Firefly Alpha LauncherOne Minotaur I IV V C Pegasus XL
In development	Antares 330 Firefly Beta New Glenn Neutron Red Dwarf Rocket 4 RS1 SLS Block 1 Block 1B Block 2 Starship Terran 1 R Vulcan
Retired	Antares 110/120/130/230 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 Falcon 1 Falcon 9 v1.0 v1.1 v1.2 "Full Thrust" H-I* Juno I Juno II N-I* N-II* Pilot Rocket 3 Saturn I IB V Scout Space Shuttle SPARK Sparta 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

Thor-Ablestar

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References

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