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|Minotaur 3, 4, 5, 6
The Minotaur 3, 4, 5, and 6 family of launch vehicles combine retired MX (Peacekeeper) ICBM stages with commercial upper stage motors to create suborbital and orbital launch vehicles for U.S. government missions. Minotaur is managed under the Orbital/Suborbital Program (OSP) by the U.S. Air Force Space and Missile Systems Center (SMC), Space Development and Test Directorate (SMC/SD) Launch Systems Division (SMC/SDL) located at Kirtland Air Force Base, New Mexico. Orbital Sciences is the prime contractor for the Minotaur program.
Development of the LSG-118 MX missile, the most powerful U.S. ICBM of its time, began in 1979. The first of 51 MX test launches took place in 1983. 50 MX missiles were deployed in underground missile silos from 1988 until 2005, when the system was retired to meet post Cold-War treaty requirements. As the missiles were retired, they were offered as government furnished equipment to be used under OSP-2, the portion of the program that ran from 2002 to 2012.
Minotaur 3 was offered as a suborbital test vehicle
beginning in 2005 or 2006, under OSP-2. It consisted of a three-stage MX missile
topped by a "Super HAPS" monopropellant hydrazine propulsion fourth stage.
Payloads weighing up to three tonnes could be boosted on intercontinental range suborbital
flights. As of mid 2017, no Minotaur 3 flights had occurred.
Minotaur 4 Inaugural, Suborbital Launch, April 22, 2010
Minotaur 4 is a four-stage solid fuel expendable launch vehicle. It uses three retired MX (Peacekeeper) ICBM stages and is topped by a commercial Orion 38 fourth stage. Orion 38, originally developed for Orbital's air launched Pegasus rocket, also serves as the fourth stage for Orbital's Taurus launch vehicle. A 2.34 meter diameter Taurus payload fairing tops the rocket.
Orbital developed Minotaur 4 under the U.S. Air Force Orbital Suborbital Program 2 (OSP-2).
Minotaur 4s avionics are derived from Orbital's Pegasus and Taurus systems. The fourth stage solid motor is integrated with avionics into a Guidance and Control Assembly (GCA). The GCA has an attitude control system to position the stage during coast periods and to provide roll control during burns.
Like its Minuteman-based Minotaur cousin, Minotaur 4 is launched from a basic pedestal platform with a fallback umbilical using minimal support equipment. Planned launch sites included Vandenberg AFB SLC 8 and Kodiak Island, Alaska. East coast launches are also plausible from Wallops Island, Virginia and Cape Canaveral, Florida.
Minotaur 4 first flew on April 22, 2010 as a three stage "Lite" variant, using only the three MX stages but controlled by Orbital avionics. The inaugural launch boosted DARPA's Hypersonic Test Vehicle (HTV)-2a from Vandenberg AFB SLC 8. The launch was successful, but HTV-2a, meant to glide through upper atmosphere at up to Mach 20 toward Kwajalein, disappeared about 9 minutes after liftoff as it reentered the upper atmosphere.
Minotaur 4 performed its first orbital launch on September 26, 2010 from Vandenberg AFB Space Launch Complex 8. The four stage solid fuel rocket orbited SBSS, the 1.03 tonne Space Based Space Surveilance satellite, for the U.S. Strategic Command. SBSS was designed to track objects in orbit using an on-board gimbaled optical sensor. Minotaur 4 lifted off at 04:41 UTC. Its first three, MX missile based stages burned in succession during the first 3 minutes 27 seconds of the flight, lifting the vehicle to a 192 km altitude and propelling it 580 km downrange. The fourth stage then coasted for about eight minutes before its Orion 38 motor ignited for a 67 second burn to inject SBSS into a 541 x 538 km x 98 deg orbit. Spacecraft separation occured about 15 minutes after liftoff.
Minotaur 4 Reaches Orbit from Alaska
The third Minotaur 4 rocket boosted seven satellites and an upper stage test vehicle into orbit from Alaska's Kodiak Launch Complex on November 20, 2010. The 24 meter tall, 88 tonne, four-stage rocket lifted off from Pad 1 at 01:25 UTC. Minotuar 4 successfully deployed its primary and secondary Space Test Program S26 satellite payloads into a 652 x 641 km x 72 deg orbit during a 15 minute span that began about 16.5 minutes after liftoff.
A HAPS (Hydrazine Auxiliary Propulsion System) stage, positioned as a fifth stage but carried as a test payload on this mission, subseqently performed a pair of burns to raise itself into a 1,200 km x 72 deg orbit.
It was the first orbital launch from Kodiak in nine years, and only the second of all time.
Nine months passed before the fourth Minotaur 4 carried
HTV-2b on a suborbital flight down the Pacific Missile Range from Vandenberg AFB SLC 8 on
August 11, 2011. The DARPA sponsered flight was a repeat of the HTV-2a mission, with
similar results. HTV-2b separated and maneuvered, but then disappeared when its
Minotaur 4 Orbits TacSat 4
Orbital's first Minotaur 4+ successfully boosted the Naval Research Laboratory's TacSat 4 satellite into orbit from Alaska's Kodiak Launch Complex on September 27, 2011. The 450 kg "Operationally Responsive" UHF communications satellite separated into a 213 x 13,866 km x 63.4 deg elliptical orbit about 28 minutes after the 15:49 UTC liftoff. TacSat 4 was expected to use its own thrusters to raise its perigee to 805 km, moving itself into a four hour orbit that will provide several hours of "dwell time" above users on the ground.
Minotaur 4+ uses a more powerful Star 48V fourth stage motor in place of the original Orion 38 motor used by Minotaur 4. The upgrade improves Minotaur 4 performance by up to 250 kg, allowing more than 1.4 tonnes to be orbited from Kodiak. Both Minotaur variants use surplus Peacekeeper ICBM motors for their first three stages.
It was the third orbital launch mission by a Minotaur 4, and the fifth Minotaur launch overall.
Its first three, MX missile based stages burned in succession during the first 3 minutes 8 seconds of the flight, propelling the fourth stage and payload on a suborbital trajectory with a 650 km apogee. Minotaur's fourth stage coasted for about 10 minutes before firing when it reached that apogee, providing orbital velocity.
Minotaur 5, also offered under OSP-2, was a Minotaur 4 upgrade that replaced the Orion 38 with a Star 48VB fourth stage and that added a Star 37FM fifth stage. The fifth stage could either be spin stabilized or could fly with a GCA-like attitude control system to provide 3-axis control. The stage would be identified as Star 37FMV in the latter case.
The September 2011 "Minotaur 4+" launch
provided a preview of the first four stages of Minotaur 5.
Minotaur 5 Launches Lunar Orbiter
Stage 4 burnout occurred 8 minutes 47 seconds after liftoff. After a roughly 6.5 minute coast period, the Star 37FM fifth stage was spun up to about 1 RPM for stabilization and ignited to accelerate LADEE toward a planned 200 x 278,000 km x 37.6 deg orbit. Stage 5 burnout occurred 18 minutes after liftoff. Spacecraft separation took place about 5.5 minutes later, after LADEE and the empty fifth stage were despun.
LADEE is expected to complete about 3.5 highly
elliptical "phasing" orbits during the next 23 days. LADEE will fire its own
propulsion system to move toward the Moon and to eventually enter lunar orbit. The
spacecraft, developed by NASA's Ames Research Center, will measure lunar dust suspended in
the near-lunar region.
It was the
first Peacekeeper based launch from Wallops Flight Facility. Orbital had previously
performed four Minuteman-based Minotaur 1 launches from the same launch pad. It was the
first Minotaur 5 launch from any site.
"Minotaur 4 Lite", uses only the first three stages for suborbital missions. A Minotaur 3 variant was offered that would have topped the MX stages with a "Super HAPS" monopropellant hydrazine propulsion fourth stage, but this variant hasn't flown. Minotaur 4 adds an Orion 38 fourth stage. A "Minotaur 4+" version with a Star 48V fourth stage has also flown. Minotaur 5 adds a Star 37FM fifth stage to the Minotaur 4+ design. The five-stage variant weighs about 88 tonnes at liftoff. With a liftoff thrust to weight ratio of about 2.5, the rocket springs off of its elevated concrete launch stand.
Five Minotaur 4 series launches have occurred since the
program began in 2010. Two were suborbital Minotaur 4 Lite missions from Vandenberg AFB.
The other three flew to orbit, one from Vandenberg AFB and two from Kodiak in Alaska.
Fifty-one Peacekeeper test flights took place between 1983 and 2003, with one 50
successes. Three additional SR-118 motors were used successfully on early Taurus
Orbital won OSP-3 funding beginning in 2013. The company promptly, in January 2013, annouced a new rocket, Minotaur 6, designed to boost heavier payloads into orbit.
Minotaur 6 is, essentially, a Minotaur 5 stacked on stop of another SR-118 stage, creating a five stage rocket that can use an optional sixth stage. Although SR-118 stages have never been stacked this way, Lockheed Martin's Athena 2 rocket stacked two Castor 120 motors in similar fashion. Castor 120 is a commercial motor developed using SR-118 as a starting point.
The rocket consists of an SR-118 first and second stages, an SR-119 third stage, an SR-120 fourth stage, a Star 48BV or optional Orion 38 fifth stage, and an optional Star 37 sixth stage that, when used, would create a "Minotaur 6+" variant.
A basic five-stage Minotaur 6 can lift 2.35 tonnes to a 200 km sun synchronous orbit from Vandenberg AFB or Kodiak. A six stage Minotaur 6+ would be able to lift 2.55 tonnes to the same orbit.
The fifth stage solid motor is integrated with avionics into a Guidance Control Assembly (GCA). The GCA has an attitude control system to position the stage during coast periods and to provide roll control during burns. No Minotuar 6 flights had occurred or been planned as of mid-2017.
During July 2015, Orbital ATK won a contract to launch ORS 5 (Operationally Responsive Space 5), also known as SensorSat, from Cape Canaveral Space Launch Complex 46. A Minotaur 4 topped by an additional Orion 38 motor serving as a fifth stage would perform the launch. The launch would put the roughly 100 kg satellite into a 600 km x 0 deg orbit, allowing the satellite to monitor objects in the geostationary belt.
It would be the first launch from SLC 46 since a Lockheed Martin Athena 1 orbited ROCSAT 1 from the site in 1999. SLC 46 was originally completed in 1985 for Trident 2 research and development launches. Nineteen Trident 2 launches were performed during 1987-1989. After Trident 2 development was completed, the site was transferred to Space Florida. In 1996, the agency began building a new mobile service tower for Athena. During 1998-99, SLC 46 supported two Athena launches, including the Lunar Prospector mission.
After years of dormancy, the Minotaur 4 mission allowed
Space Florida to perform renovations at the site and, during early 2017, a pathfinder
Minotaur 4 was stacked on the pad.
MX (Peacekeeper) Variants =================================================================================== Name Stage 1 Stage 2 Stage 3 Stage 4 Stage 5 Stage 6 ----------------------------------------------------------------------------------- Peacekeeper SR-118 SR-119 SR-120 PBM Athena I Castor 120 Orbus 21D OAM Athena II Castor 120 Castor 120 Orbus 21D OAM Taurus 1XXX SR-118 Orion 50S Orion 50 Orion 38 Taurus 2XXX Castor 120 Orion 50SG Orion 50 Orion 38 Taurus 3XXX Castor 120 Orion 50SXL Orion 50XL Orion 38 Minotaur 3 SR-118 SR-119 SR-120 SuperHAPS Minotaur 4 SR-118 SR-119 SR-120 Orion 38 Minotaur 5 SR-118 SR-119 SR-120 Star 48V Star 37FM Minotaur 6(+) SR-118 SR-118 SR-119 SR-120 Star 48VB (Star 37FM) ===================================================================================
MINOTUAR 3,4,5,6 LAUNCH LOG ==================================================================================== ==================================================================================== Date Vehicle ID Payload Mass Site* Orbit Orbit kg (kmxkmxdeg) Type** ------------------------------------------------------------------------------------ 04/22/10 Minotaur 4 Lite MT4-1 HTV 2a VA 8 SUB  09/26/10 Minotaur 4 MT4-2 SBSS 1 1031 VA 8 538x541x98 LEO/S 11/20/10 Minotaur 4 HAPS MT4-3 STP S26 590 KD 1 641x652x72 LEO 08/11/11 Minotaur 4 Lite MT4-4 HTV 2b VA 8 SUB  09/27/11 Minotaur 4+ MT4-5 TacSat 4 450 KD 1 213x13866x63.4 EEO  09/07/13 Minotaur 5 MT5-1 LADEE 380 WI 0B 200x278000x37.6 EEO  ------------------------------------------------------------------------------------  DARPA Hypersonic Test Vehicle 2a meant to glide through upper atmosphere at up to Mach 20 to dive near Kwajalein, but contact lost 9 min after liftoff.  Minotaur 4 Lite success, but HTV 2b telemetry stopped  1st Minotaur 4+ with Star 48V stage. Four hour elliptical orbit.  200 x 278,000 km x 37.6 deg phasing orbit. LADEE boost itself to lunar orbit. First Minotaur 5, first PK based and beyond-LEO launch from WI. ==================================================================================== References
Minotaur 3 Fact Sheet, Orbital Sciences, 2006
Last Update: May 20, 2017