Minotaur-C

Minotaur-C (Taurus)

Taurus 1110 preparing to launch STEP 0 on March 13, 1994.
Function	Orbital launch vehicle
Manufacturer	Orbital Sciences, Orbital ATK
Country of origin	United States
Size
Height	27.9 m (91.5 ft)
Diameter	2.35 m (7.7 ft)
Mass	73,000 kg (160,000 lb)
Stages	4
Capacity
Payload to LEO	1,320 kg (2,910 lb)
Launch history
Status	Active
Launch sites	Wallops Flight Facility LC-576E, Vandenberg AFB Cape Canaveral Kodiak Launch Complex
Total launches	9
Successes	6
Failures	3
First flight	13 April 1994, 22:32 UTC USA 101/USA 102
First stage - Castor 120
Engines	1 solid
Thrust	1,606.6 kN (361,177 lbf)
Specific impulse	286 sec
Burn time	83 seconds
Fuel	Solid
Second stage - Taurus-1
Engines	1 solid
Thrust	484.9 kN (109,012 lbf)
Specific impulse	285 sec
Burn time	73 seconds
Fuel	solid
Third stage - Pegasus-2
Engines	1 solid
Thrust	118.2 kN (26,570 lbf)
Specific impulse	292 sec
Burn time	73 seconds
Fuel	solid
Fourth stage - Pegasus-3
Engines	1 solid
Thrust	34.57 kN (7,770 lbf)
Specific impulse	293 sec
Burn time	65 seconds
Fuel	solid

Minotaur-C (Minotaur Commercial), formerly known as Taurus,^[1] is a four stage, solid fuel launch vehicle built in the United States by Orbital Sciences Corporation (now Orbital ATK). It is based on the air-launched Pegasus rocket from the same manufacturer. The Minotaur-C is able to carry a payload of around 1,350 kg into a low Earth orbit. First launched in 1994, it has successfully completed six out of a total of nine military and commercial missions.^[2] Three of four launches between 2001 and 2011 ended in failure, including the February 24, 2009 launch of the Orbiting Carbon Observatory mission^[3] and the March 4, 2011 launch of the Glory mission.^[4] The failure of the two latest launches resulted in losses totalling $700 million for NASA (not including cost of the rockets themselves).^[5][6] The rocket was subsequently rebranded as the Minotaur-C, which incorporates new avionics based on those used by the Minotaur series of rockets.^[1][2]

Stages

The Minotaur-C's first stage, an Orbital ATK Castor 120, is based on a Peacekeeper ICBM first stage. Stages 2 and 3 are Orion-50s (like the Pegasus-1 but without wings or stabilisers), and stage 4 is an Orion 38, derived from the Pegasus-3.^[7]

Numbering system

Different configurations are designated using a four digit code, similar to the numbering system used on Delta rockets. The first digit denotes the type of first stage being used, and whether the second and third stages use a standard or "XL" configuration.^[8][9] The second digit denotes the diameter of the payload fairing.^[8] The third digit denotes the type of fourth stage.^[8] The fourth digit denotes an optional fifth stage, so far unused.^[8]

List of launches

Launch failures

Orbview-4

On September 21, 2001, a Taurus XL rocket failed during launch. When the second stage ignited at T+83 seconds, a nozzle gimbal actuator drive shaft seized for approximately 5 seconds causing loss of control. The vehicle recovered and continued to fly the mission profile, but failed to reach a stable orbit and reentered near Madagascar.^[12]

Orbiting Carbon Observatory

On February 24, 2009, a Taurus XL rocket failed during the launch of the $270m Orbiting Carbon Observatory spacecraft.^[13] Liftoff occurred successfully at 09:55 GMT from Vandenberg Air Force Base, but data received at a later stage of the flight suggested that the fairing failed to separate. The rocket did not reach orbit,^[3] owing to the extra weight of the fairing.^[5][11] Launch vehicle and services for OCO are estimated at $54m.^[14] The replacement satellite, Orbiting Carbon Observatory-2, was launched July 2, 2014.^[15][16][17]

Glory

On March 4, 2011, a Taurus XL rocket failed again during the launch of NASA's $424 million Glory climate change monitoring satellite. In total, the last two failures of the Taurus XL have resulted in payload losses worth $700 million.^[6] The reason for the failure was the same as with OCO: the payload fairing failed to separate, although the rocket's manufacturer Orbital Sciences Corporation had spent the last two years trying to fix the problem and had made several design changes to the fairing separation system. Ronald Grabe, manager of Orbital Sciences Corporation, which also built the Glory satellite itself, said the employees of his companies are "pretty devastated" because of the latest failure.^[5] The fairing was built by the Vermont Composites company, and the frangible rail pyrotechnic separation system was built by the Ensign-Bickford Company. A NASA MIB panel concluded that the failure was most likely caused by a section of the frangible rail somewhere near the nose cap failing to separate. While a root cause could not be identified, two likely causes were identified: the rubber charge holder in the frangible rail slumping due to launch acceleration and random vibration, or a failure of the frangible rail system due to it operating outside the environment for which it was tested.^[18]

Ground-Based Interceptor

The upper stages of the Minotaur-C are used by the boost vehicle of the Ground-Based Interceptor,^[19] the anti-ballistic missile component of the U.S. Missile Defense Agency's Ground-Based Midcourse Defense system.

See also

• Comparison of orbital launchers families
• Antares, an Orbital ATK rocket with a liquid first stage and a modified Castor 120 solid rocket as a second stage. Originally named Taurus II.^[20]
• Official fact sheet (2015)

References

Wikimedia Commons has media related to Taurus (rocket).