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Minotaur IV

The first launch of the Minotaur IV Space Launch Vehicle is scheduled to occur 20 April 2010 at noon PDT from Vandenberg Air Force Base, Calif. The Minotaur IV is the newest variant in the Minotaur family of rockets built by Orbital Sciences Corporation. It is a four-stage solid rocket vehicle consisting of three decommissioned Peacekeeper missile stages and a fourth commercially built stage developed by OSC. For this maiden lift-off, the rocket will be in a "lite" configuration consisting of only the first three stages and no fourth stage due to mission requirements.

The OSP-2 Minotaur IV SLV, combines elements of government-furnished decommissioned Peacekeeper boosters with technologies from the proven Pegasus®, Taurus® and OSP Minotaur launch vehicles. The vehicle consists of three Peacekeeper solid rocket stages, a commercial Orion 38 fourth stage motor and subsystems derived from our established space launch boosters. Under a 10-year contract with the U.S. Air Force Space and Missile Systems Center, Orbital developed and operated the low-cost Minotaur IV vehicle to launch U.S. government-funded satellites into low-Earth orbit.

The Minotaur IV SLV incorporates a standard 92-inch fairing from our Taurus booster and supports dedicated or shared launch missions. Capable of boosting payloads more than 1,750 kg into orbit, the vehicle is compatible with multiple U.S. government and commercial launch sites. The Minotaur IV is designed to provide 18-month mission response including payload integration and launch by Orbital's experienced launch crews.

The primary mission of the Minotaur IV is to provide low cost, high reliability launch services to government-sponsored payloads. Minotaur IV accomplishes this using flight-proven components with a significant flight heritage such as surplus Peacekeeper boosters, the Taurus Fairing and Attitude Control System, and a mix of Minotaur I, Pegasus, Taurus, and other orbital standard avionics, all with a proven, successful track record.

The Minotaur IV launch vehicle system is composed of a flight vehicle and ground support equipment. Each element of the Minotaur IV system has been developed to simplify the mission design and payload integration process and to provide safe, reliable space launchservices.

By adopting the austere launch site concepts developed for Taurus, the Minotaur IV system can operate from a wide range of launch facilities and geographic locations. The system is compatible with, and will typically operate from, commercial spaceport facilities and existing U.S. Government ranges at Vandenberg Air Force Base (VAFB), Cape Canaveral Air Force Station (CCAFS), Wallops Flight Facility (WFF), and Kodiak Island, Alaska.

The Minotaur IV vehicle is a four-stage, inertially guided, all solid propellant ground launched vehicle. Conservative design margins, state-of-the-art structural systems, a modular avionics architecture, and simplified integration and test capability, yield a robust, highly reliable launch vehicle design. In addition, Minotaur IV payload accommodations and interfaces have been designed to satisfy a wide range of potentialpayload requirements.

The first three stages of the Minotaur IV consists of the refurbished Government Furnished Equipment (GFE) Peacekeeper Stages 1, 2 and 3. These booster assemblies are used as provided by the Government, requiring no modification oradditional components. They have extensive flight history, including 51 Peacekeeper launches and three Stage 1 launches on Taurus with no motor related failures. All three stages are solid-propellant motors and utilize a movable nozzle controlled by a Thrust Vector Actuator (TVA)system for three-axis attitude control.

The first stage consists of a Thiokol motor that provides 500,000 lbf (2224 kN) of thrust. The second stage motor is an Aerojet motor with a moveable nozzle contoured with an extendable exit cone. It provides an average thrust of 275,000 lbf(1223 kN). The third stage is a Hercules motor that provides 65,000 lbf (289 kN) of thrust and also features an extendable exit cone similar to Stage 2.

The Minotaur IV Stage 4 motor is the Orion 38 design. This motor was originally developed for Orbital's Pegasus program and isused on the Minotaur I launch vehicle, as well asother Orbital launch vehicles. Common design features, materials and production techniques are applied to the motors to maximize reliability andproduction efficiency. The Orion 38 motor provides the velocity needed for orbit insertion for the SLV, in the same manner as it is used on the Minotaur. This motor features state-of-the-artdesign and materials with a successful flightheritage. It is currently in production and isactively flying payloads into space, with 37 fully successful flights to date and one static test.