Minotaur

For the U.S. Air Force's Orbital/Suborbital Program (OSP) Orbital Sciences Corporation developed the low-cost, four-stage Space Launch Vehicle (SLV) Minotaur rocket using a combination of U.S. government-supplied Minuteman II motors and proven Orbital space launch technologies.

The Minuteman rocket motors serve as the vehicle's first and second stages, efficiently reusing motors that have been decommissioned as a result of arms reduction treaties. Minotaur's third and fourth stages, structures and payload fairing are common with our highly reliable Pegasus XL rocket. Its capabilities have been enhanced with the addition of improved avionics systems, including our Modular Avionics Control Hardware (MACH), which is used on many of our suborbital launch vehicles.

Minotaur made its inaugural flight in January 2000, successfully delivering a number of small military and university satellites into orbit and marking the first-ever use of residual U.S. Government Minuteman boosters in a space launch vehicle. Minotaur extended its 100% success record less than six months later, in July 2000, with the launch of a technology demonstration satellite for the Air Force Research Laboratory.

The primary program goal is to provide low cost, reliable space launch capability in support of U.S. government small-satellite launch requirements. The program was structured to incorporate most of the development risk in the first mission followed by routine launch services operations.

On Monday, April 11, 2005, the predawn darkness at California's Vandenberg Air Force Base was broken as an Orbital Minotaur rocket roared to life. Approximately 12 minutes later, Minotaur delivered the U.S Air Force's Experimental Small Satellite Number 11 (XSS-11) into its target orbit 850 kilometers above the Earth. The launch was the first mission of the Minotaur space launcher since its two successful inaugural launches in 2000. The XSS-11 mission was the first of up to three-planned Minotaur launches 2005 and marked a coming of age of sorts for Orbital's Minotaur Space Launcher Family.

SPACE LAUNCH VEHICLE DESCRIPTION
The Minotaur has the following characteristics:

1. Stage 1 (Minuteman II M-55A1)
    a. Size: 66 inches in diameter and 24.6 feet long
    b. Weight: 51,514 pounds
    c. Thrust: About 200,435 pounds (force)

2. Stage 2 (Minuteman II SR-19)
    a. Size: 52 inches in diameter and 13.5 feet long
    b. Weight: 13,740 pounds
    c. Thrust: About 60,000 pounds (force)

3. Stage 3 (Pegasus XL Orion 50 XL)
    a. Size: 50 inches in diameter and 12.1 feet long
    b. Weight: 918 pounds
    c. Thrust: About 44,171 pounds (force)

4. Stage 4 (Pegasus XL Orion 38)
    a. Size: 38 inches in diameter and 4.4 feet long
    b. Weight: 278 pounds
    c. Thrust: About 8,062 pounds (force)

VEHICLE PERFORMANCE
Minotaur is considered a small launch vehicle. It can lift 750 pounds to a 400- nautical mile, sun-synchronous orbit. This is roughly 1.5 times the Pegasus XL capability.
Minotaur can operate with two fairings allowing for the launch of oversized payloads. The standard configuration uses a slightly modified Pegasus fairing. It has a dynamic payload volume of about 46 inches in diameter by 88 inches long. The larger fairing has a dynamic payload volume of about 61 inches in diameter and is about 133 inches long.
Using the multi-payload adapter developed through a contract with One Stop Satellite Solutions (OSSS) of Ogden Utah, Minotaur is capable of launching one large primary payload and up to four secondary payloads.

OPERATIONAL DETAILS
Minotaur is a ground launched system. It uses a launch scheme very similar to the existing Taurus launch vehicle.
This is composed of:

20-foot tall launch stool
Sacrificial umbilical tower
Movable gantry system (composed of commercially procured scaffolding)
Launch Support Van (LSV) that contains the launch vehicle support equipment and houses the launch team during operations
Launch Equipment Vault (LEV) that houses batteries and other support equipment on the launch pad.

Minotaur is required to be compliant with international arms control treaties due to the usage of the M55A1 first stage motor. The treaty compliance requirements include the requirement to capture all vehicle telemetry and certain limitations on launch locations for the vehicle.

PAYLOADS
The payload for the first mission was a composite payload of two larger DoD payloads and three small micro satellite payloads. The prime payloads were the U.S. Air Force Academy's FalconSat satellite and the Air Force JAWSAT satellite. The JAWSAT vehicle also served as a multi-payload adapter carrying three micro satellites. The micro satellites included the Optical Calibration Spheres, Stanford University's Opal satellite, and Arizona State University's satellite (ASUSAT). Additional experiments supported by the multi-payload adapter were the attitude control platform developed by One Stop Satellite Solutions and Weber State University, and NASA's plasma experiment satellite test. The demonstration mission launched on 26 January, 1999. The second OSP Space Launch Vehicle mission launched the Air Force Research Laboratory's MightySat II.1 payload on 19 July, 2000.

LAUNCH SITES
The vehicle is currently capable of launching from a government pad at Vandenberg Air Force Base, Calif., as well as commercial spaceports at Wallops Island, Va., Cape Canaveral, Fla., Vandenberg AFB, Calif., and Kodiak Island, Alaska. In addition, to ensure no adverse impacts to the U.S. commercial space launch capability, all payload customers must be U.S. government agencies or be sponsored by such agencies. The Secretary of Defense holds approval power for each launch mission.

CONTRACT
The Orbital Suborbital Program contract was awarded to Orbital Sciences Corporation in September 1997 to use surplus Minuteman II components for sub-orbital and orbital spacelift in support of U.S. Government requirements.

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