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New Minotaur rocket to debut in October

Posted: August 3, 2009

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The Minotaur 4 rocket, a new military launcher derived from retired missile parts, will debut in October with an experimental Air Force mission that will track other satellites in space.

Launch of the Minotaur 4 rocket is scheduled for Oct. 22 at 9:41 p.m. PDT (12:41 a.m. EDT; 0441 GMT on Oct. 23), the Air Force has announced.

The pathfinder Minotaur 4 stands on its California launch pad. Credit: Orbital Sciences
The Minotaur 4 will lift off from Space Launch Complex 8 at the southern end of Vandenberg Air Force Base, Calif.

Managed by Orbital Sciences Corp., the new rocket was developed as a low-cost solution for small- to medium-class military satellites. The four-stage launcher will be able to throw more than 3,000 pounds into low-altitude orbits, according to Orbital.

The Minotaur 4's first payload will be the Space-Based Space Surveillance satellite. This first-of-a-kind spacecraft carries an optical telescope to detect high-altitude satellites in the geosynchronous belt about 22,300 miles from Earth.

The $800 million mission, also called SBSS Block 10, will join an array of ground-based radars that track thousands of objects in orbit.

SBSS is ready to be delivered to Vandenberg, pending final reviews, according to a spokesperson at the Air Force Space and Missile Systems Center.

"We do not foresee any constraints to the space vehicle meeting the (launch date)," an SMC Space Superiority Systems Wing spokesperson said.

The 2,200-pound satellite will be mated with the Minotaur rocket's fourth stage motor a few weeks before launch.

The first launch of the new rocket was delayed from earlier this year to ensure the flight would not suffer the fate of a doomed Taurus rocket that failed in February.

"The intent was to investigate if the failure was related to common components between Taurus and Minotaur 4," the Air Force spokesperson said.

Engineers determined the most likely cause of the Taurus failure was a glitch in a hot gas generator powering pneumatic pushers that separate the payload fairing.

According to the Air Force, the Minotaur 4's shroud was exonerated because the rocket uses a larger payload fairing with a different separation system.

The Minotaur 4 rocket's first three stages are decommissioned Peacekeeper missile motors. The components were retired from active service between 2002 and 2005.

The fourth stage is an Orion 38 motor used on Orbital's Pegasus, Taurus and Minotaur 1 rockets.

Workers completed a "pathfinder" exercise last year using inert Minotaur 4 stages at the Vandenberg launch site. The rocket was fully assembled and stacked atop the launch pad to validate procedures and equipment, according to Orbital.

The test also gave engineers valuable practice in lifting operations.

The Minotaur 1 rocket, powered by former Minuteman stages, has achieved eight successful launches for military payloads. The smaller booster is a technical and programmatic predecessor to the Minotaur 4.

At least eight Minotaur 4 launches, including suborbital missions, are on the books during the next few years from Vandenberg and Kodiak Island, Alaska.