Thor-Able

Thor-Able

Launch of the Transit 1A satellite on a Thor-Able II
Function	Expendable launch system Sounding rocket
Manufacturer	Douglas/Aerojet
Country of origin	United States
Size
Height	26.9 metres (88 ft) - 27.8 metres (91 ft)
Diameter	2.44 metres (8 ft 0 in)
Mass	51,608 kilograms (113,776 lb)
Stages	2-3
Capacity
Payload to 640km LEO	120 kilograms (260 lb)
Associated rockets
Family	Thor
Derivatives	Thor-Ablestar Delta
Comparable	Luna
Launch history
Launch sites	LC-17A, Canaveral
Total launches	16
Successes	10
Failures	6
First flight	24 April 1958
Last flight	1 April 1960
Notable payloads	Pioneer Transit Tiros
First stage - Thor
Engines	1 LR79-7
Thrust	758.71 kilonewtons (170,560 lbf)
Specific impulse	282 sec
Burn time	165 seconds
Fuel	RP-1/LOX
Second stage - Able
Engines	1 AJ-10
Thrust	34.69 kilonewtons (7,800 lbf)
Specific impulse	270 sec
Burn time	115 seconds
Fuel	HNO3/UDMH
Third stage (optional) - Altair
Engines	1 X-248
Thrust	12.45 kilonewtons (2,800 lbf)
Specific impulse	256 sec
Burn time	38 seconds
Fuel	Solid

The Thor-Able was an American expendable launch system and sounding rocket used for a series of re-entry vehicle tests and satellite launches between 1958 and 1960. It was a two stage rocket, consisting of a Thor IRBM as a first stage, and a Vanguard-derived Able second stage. On some flights, an Altair solid rocket motor was added as a third stage. It was a member of the Thor family, and an early predecessor of the Delta.

Sixteen Thor-Ables were launched, nine on sub-orbital re-entry vehicle test flights, and seven on orbital satellite launch attempts. Six launches resulted in failures, in which three of those failures were the result of an Altair upper stage added to the rocket to allow it to launch the spacecraft onto a trans-lunar trajectory. All sixteen launches occurred from Cape Canaveral Air Force Station Launch Complex 17A.

The Thor-Able vehicle had a stronger airframe than the standard Thor IRBM and had the inertial guidance system replaced by a radio guidance package mounted on the Able stages. It saw its first test on April 23, 1958 when Vehicle 116 was launched from LC-17A with a biological nose cone containing a mouse named MIA (Mouse In Able). At 7:10 PM EST, the Thor's engine roared to life and drove the Able stage and its tiny passenger into the evening sky. Two minutes and fifteen seconds after launch, at an altitude of 50 miles (80 km), the Thor exploded and sent the hapless rodent into the Atlantic Ocean instead of space. The cause of the failure was traced to a turbopump bearing coming loose and resulting in pump shutdown and instant loss of thrust. With no attitude control, the Thor pitched down and its LOX tank ruptured from aerodynamic loads. On July 9, Thor 118 lifted off for a second attempt with a mouse named MIA II. The booster, including the unproven Able stage, performed successfully and the biological nose cone was driven back into the atmosphere for splashdown in the South Atlantic, but recovery crews failed to locate the capsule and it sank into the ocean. A third attempt was made on July 23. The press refused to call the mouse by the name of MIA III, so she was instead christened "Wickie", after a local female news reporter who had covered the space program at Cape Canaveral. Unfortunately, Wickie was no more lucky than her predecessors when recovery crews once again failed to locate the capsule after splashdown, but telemetry data confirmed the mouse's survival from liftoff through reentry and proved comprehensively that living organisms could survive space travel. Attention now turned to Thor-Able 127 and Pioneer 0, the world's first lunar probe. This flight took place on August 17, but ended embarrassingly when the Thor exploded 77 seconds into the launch due to another turbopump malfunction. After an Atlas missile test a month later also failed due to the turbopumps, the Air Force Ballistic Missile Division quickly replaced the pumps in all of their missiles and this problem did not repeat itself again.