Launch of the first Minotaur IV Lite
|Function||Expendable launch system|
|Cost per launch (2013)||$50 million|
|Height||23.88 meters (78.3 ft)|
|Diameter||2.34 meters (7 ft 8 in)|
|1735 kg (28.5 deg, 185 km)|
|Launch sites||SLC-8, Vandenberg AFB
|First flight||22 April 2010|
|First Stage - SR-118|
|Thrust||2,200 kN (490,000 lbf)|
|Second Stage - SR-119|
|Thrust||1,365 kN (307,000 lbf)|
|Burn time||54 seconds|
|Third Stage - SR-120|
|Thrust||329 kN (74,000 lbf)|
|Burn time||62 seconds|
|Fourth Stage (Baseline) - Orion-38|
|Thrust||32.2 kN (7,200 lbf)|
|Burn time||67.7 seconds|
|Fourth Stage (Optional) - Star-48V|
|Thrust||68.6 kN (15,400 lbf)|
|Burn time||84.1 seconds|
Minotaur IV, also known as Peacekeeper SLV and OSP-2 PK is an active expendable launch system derived from the LGM-118 Peacekeeper ICBM. It is operated by Orbital Sciences Corporation, and made its maiden flight on 22 April 2010, carrying the HTV-2a Hypersonic Test Vehicle.  The first orbital launch occurred on 26 September 2010 with the SBSS satellite for the United States Air Force.
The Minotaur IV vehicle consists of four stages and is capable of placing 1,735 kilograms (3,825 lb) of payload into a Low Earth orbit (LEO). It uses the first three stages of the Peacekeeper missile, combined with a new upper stage. On the baseline version, the fourth stage is an Orion-38. However a higher performance variant, designated Minotaur IV+, uses a Star-48V instead. A three stage configuration (no Orion-38), designated the Minotaur IV Lite, is available for Suborbital trajectories. A five stage derivative, the Minotaur V, made its maiden flight on 7 Sep 2013.
|Date/Time (UTC)||Variant||Launch Site||Payload||Trajectory||Outcome||Remarks|
|22 April 2010
|Minotaur IV Lite||Vandenberg SLC-8||HTV-2a||Suborbital||Successful||Successful launch, but payload failed|
|26 September 2010
|Minotaur IV||Vandenberg SLC-8||SBSS||SSO||Successful|
|20 November 2010
|Minotaur IV HAPS||Kodiak LP-1||STPSat-2
|LEO||Successful||STP-S26 launch. Included a Hydrazine Auxiliary Propulsion System (HAPS) to take the vehicle to a secondary orbit after placing payloads into the primary orbit.|
|11 August 2011
|Minotaur IV Lite||Vandenberg SLC-8||HTV-2b||Suborbital||Successful||Successful launch, but payload failed|
|27 September 2011
|Minotaur IV+||Kodiak LP-1||TacSat-4||LEO||Successful||First Minotaur IV+ launch|
|TBD||Minotaur IV||Vandenberg SLC-8||TacSat-5||LEO||Might launch on a Minotaur I|
|TBD||Minotaur IV Lite||Vandenberg SLC-8||CSM||Suborbital|
The third Minotaur IV launch, which was also known as STP-S26, deployed eight payloads. The 26th small launch vehicle mission in STP's 40-year history of flying DoD space experiments, STP-S26 was intended to extend previous standard interface development efforts, implementing a number of capabilities aimed at enabling responsive access to space for small experimental satellites and payloads. STP-S26 launched at 01:45 UTC on 20 November 2010 from the Kodiak Launch Complex. The launch facility contractor was Alaska Aerospace Corporation (AAC). The payloads were released in a 650-kilometer (400 mi) orbit, before the HAPS upper stage was demonstrated by deploying two ballast payloads into a 1,200 km (750 mi) orbit.
The primary objective of the STP-S26 launch was to deploy STPSat-2, whilst demonstrating the ability of the Minotaur IV to carry additional payloads, by deploying FASTSAT, FASTRAC, RAX, O/OREOS and FalconSat-5. A Hydrazine Auxiliary Propulsion System upper stage was flown aboard the Minotaur to demonstrate its ability to deploy payloads to multiple orbits, however only mass simulators were deployed after the HAPS burn.
The launch marked the first flight of a STP-SIV (Standard Interface Vehicle) satellite, the first use of the Multi Mission Satellite Operations Center Ground System Architecture (MMSOC GSA),, the first flight of the Minotaur IV's Multi-payload Adapter (MPA), the first use of a HAPS to obtain multiple orbits on a Minotaur IV flight, the first Minotaur launch from Kodiak Launch Complex (KLC), and the first deployment of CubeSats from a Minotaur IV viaPoly-PicoSatellite Orbital Deployers (P-Pods).
- Stephen Clark (November 18 2010). "Minotaur rocket poised to send research to new heights". Spaceflight Now.
- "Orbital Successfully Launches First Minotaur IV Rocket for U.S. Air Force" (Press release). Orbital Sciences Corporation. April 27, 2010.
- "Air Force Space Officials Prepare To Launch First Minotaur IV". Air Force News Service. April 16, 2010. Archived from the original on July 29, 2012.
- Graham, William (April 22, 2010). "First Minotaur IV launches with Hypersonic Test Vehicle". NASAspaceflight.com.
- "Minotaur IV Fact Sheet" (PDF). Orbital Sciences Corporation. 2010. Retrieved 2009-03-04.
- Krebs, Gunter. "Minotaur-3/-4/-5 (OSP-2 Peacekeeper SLV)". Gunter's Space Page. Retrieved 2009-03-04.
- Schaub, Michael B.; Schwartz, Patrick C. "Launches". Mission Set Database. NASA/Honeywell-TSI. Retrieved 23 April 2010.
- Hope, Dan. "DARPA Readies Hypersonic Aircraft for Mach 20 Launch Test". Retrieved 10 Aug 2011.