Minotaur (rocket family)

The Minotaur is a family of United States solid-fuel launch vehicles derived from retired Minuteman and Peacekeeper intercontinental ballistic missiles (ICBM). Built by Northrop Grumman under the U.S. Space Force's Rocket Systems Launch Program, the vehicles are used for orbital and suborbital missions.

The Minotaur family consists of four primary variants: the Minotaur I, used for launching small satellites into low Earth orbit; the Minotaur II, used primarily as a suborbital target vehicle; the Minotaur IV, a small-lift orbital launch vehicle; and the Minotaur V and Minotaur VI, capable of higher-energy missions including geostationary transfer orbit and trans-lunar trajectories. Minotaur I and II are derived from the LGM-30 Minuteman ICBM, while Minotaur IV, V, VI and the cancelled Minotaur III are based on the LGM-118 Peacekeeper ICBM.

The Taurus launch vehicle, later renamed^[1] Minotaur-C (for "Minotaur-Commercial"), was the first of the Minotaur family and the first ground-launched orbital booster developed by Orbital Sciences Corporation (OSC). It was derived by adding a solid booster stage to the air-launched Pegasus rocket.

The first flight, sponsored by DARPA, occurred in 1994. Following a series of failures between 2001 and 2011, the vehicle was rebranded as Minotaur-C in 2014. Due to restrictions on the commercial use of government-furnished hardware, Minotaur-C is the only Minotaur vehicle available for commercial launches.

The original Minotaur launch vehicle consists of an M55A1 first stage, SR19 second stage, Orion 50XL third stage, Orion 38 fourth stage, and an optional HAPS fifth stage for velocity trimming and multiple payload deployment. It can deliver 580 kilograms (1,280 lb) to a 185 kilometres (115 mi) orbit at 28.5° inclination from Cape Canaveral, or 310 kilograms (680 lb) to a 740 kilometres (460 mi) Sun-synchronous orbit from Vandenberg.^[2]

The Minotaur II is a suborbital target vehicle derived from the Minuteman II missile, incorporating Orbital guidance and control systems. It consists of an M55A1 first stage, SR19 second stage, and M57 third stage, and can carry a payload of 460 kilograms (1,010 lb) on a 6,700 kilometres (4,200 mi) suborbital trajectory.^[2]

The Minotaur III was a proposed suborbital target vehicle consisting of an SR118 first stage, SR119 second stage, SR120 third stage, and Super HAPS fourth stage. It was designed to carry 3,060 kilograms (6,750 lb) on a 6,700 kilometres (4,200 mi) suborbital trajectory.^[2] Development was cancelled and the vehicle was never flown.

The Minotaur IV combines decommissioned Peacekeeper solid rocket motors with technologies from other Orbital-built launch vehicles, including Minotaur I, Pegasus, and Taurus. It consists of an SR118 first stage, SR119 second stage, SR120 third stage, and Orion 38 fourth stage. It can deliver 1,735 kilograms (3,825 lb) to a 185 kilometres (115 mi) orbit at 28.5° inclination from Cape Canaveral.

The first launch occurred on April 22, 2010, from Vandenberg in California.^[3] The vehicle has also been used in support of the U.S. Air Force's Conventional Prompt Global Strike (CPGS) program.

The Minotaur V is a five-stage variant based on the Minotaur IV+, incorporating an additional upper stage for missions to geostationary transfer orbit, lunar trajectories, and interplanetary destinations.

NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) was launched on the first Minotaur V from the Wallops Flight Facility in Virginia at 03:27 UTC on September 7, 2013. The vehicle placed LADEE into a highly elliptical orbit to enable phasing for lunar transfer.^[4]

The Minotaur VI is a proposed five-stage launch vehicle developed by Northrop Grumman that, as of 2025, has not flown. It is based on the Minotaur IV+, with the addition of a second SR-118 first stage to increase performance.^[5] An enhanced variant, Minotaur VI+, is also proposed for beyond low Earth orbit missions, incorporating an additional Star 37FM sixth stage. This configuration is projected to deliver up to 300 kilograms (660 lb) to Mars.

• Dnepr, a converted Soviet ICBM often used for commercial satellite launches
• Modified Minotaur IV (Ascent Abort-2), Ascent Abort-2 (AA-2), was a suborbital flight to test the Launch Abort System (LAS) of NASA's Orion spacecraft. The suborbital flight used a modified Minotaur IV, launched July 2, 2019, at 11:00 UTC from CCAFS SLC-46. The suborbital flight was a success.

• Minotaur I Rocket page
• Minotaur IV Rocket page
• NASA Astronomy Picture of the Day: Image of the September 2005 launch (September 28, 2005)
• Encyclopedia Astronautix Entry for Minotaur