Q: Congratulations! You're the United States Air Force, and it's December 22, 1997. In accordance with the Strategic Arms Reduction Treaty you've just destroyed the last Minuteman II nuclear missile silo in the world. What are you going to do next?
A: We're going to find some something to do with 450 disassembled Minuteman missiles we've suddenly got lying around!
Okay, you caught me. This isn't a transcript of an actual exchange between some over-eager newscaster and some unnamed U. S. Air Force officer, but it is representative of the thought process in the USAF during the period of disarmament that followed the end of the Cold War. The Minuteman II missile, first delivered to the Air Force in 1966, was built to last - the missile's solid fuel has an effectively indefinite shelf life - and it occurred to some members of the defense community that, with a few modifications, the Minuteman II could be turned into an entirely serviceable and relatively affordable satellite launch platform. The project was considered by Air Force officials and deemed worthy of further study. This project to adapt the Minuteman II to serve as a satellite launch system was styled the Orbital/Suborbital Program (OSP).
Minotaur
The winner of the OSP contract was Orbital Sciences Corporation, a Virginia-based company with experience in both orbital and sub-orbital rocketry, most notably their Pegasus launch vehicle. The Air Force's decision to award Orbital the OSP contract was based in no small part on the very high success rate of the Pegasus vehicle, a slightly modified version of which formed the third and fourth stages of the proposed Minotaur launcher.
According to the Air Force, the Minotaur is capable of placing a 750-pound payload into a 400-nautical mile, sun-synchronous orbit; this is roughly 1.5 times the payload of the Pegasus launcher to a similar orbit. The Minotaur is used exclusively to loft payloads destined for Low Earth Orbit. Minotaur launches can be accommodated at the following locations: Vandenberg Air Force Base, California; Kodiak Island, Alaska; Wallops Island, Virginia; and Cape Canaveral, Florida. The Minuteman II Minotaur launchers come in two flavors: Minotaur I, incorporating a standard 50-inch payload fairing adapted from the Pegasus; and Minotaur II, which uses a 61-inch fairing for larger payloads.
The Minotaur achieved first flight in January of 2000. This was first use of a remaindered Minuteman ICBM for space launch purposes; this mission placed several small government and university satellites into orbit. The Minotaur currently (4/13/05) has a success rating of 100%.
Stage Data:
Stage 1 (Minuteman II M-55A1)
Stage 2 (Minuteman II SR-19)
- Diameter: 52 inches
- Length: 13.5 feet
- Weight: 13,740 pounds
- Thrust: ~ 60,000 pounds
Stage 3 (Pegasus XL Orion 50 XL)
- Diameter: 50 inches
- Length: 12.1 feet
- Weight: 918 pounds
- Thrust: ~ 44,171 pounds
Stage 4 (Pegasus XL Orion 38)
- Diameter: 38 inches
- Length: 4.4 feet
- Weight: 278 pounds
- Thrust: ~ 8,062 pounds
Minotaur IV
Based on the success of the Minuteman II-derived Minotaur satellite launch system, Orbital Sciences was tapped by the Air Force to adapt the soon-to-be retired Peacekeeper missile for the same purpose. The Minotaur IV is currently in research and development. It is expected to incorporate a 92 inch fairing and loft payloads of up to 1750 kilograms (3850 pounds) into orbit. Its inaugural payload is scheduled to be the Air Force's Space-Based Space Surveillance system; this payload is scheduled to launch in 2007.
Sources:
Federation of American Scientists:
http://www.fas.org/nuke/guide/usa/icbm/lgm-30_2.htm
Orbital Sciences:
http://www.orbital.com/SpaceLaunch/Minotaur/index.html
http://www.orbital.com/NewsInfo/Publications/Minotaur_fact.pdf
United States Air Force:
http://www.losangeles.af.mil/SMC/PA/Fact_Sheets/minotaur_fs.htm