[American Institute of Aeronautics and Astronautics AIAA SPACE 2007 Conference & Exposition - Long...

1 American Institute of Aeronautics and Astronautics

Minotaur-Family Launch Vehicles Responsive Launch Demonstration for the TacSat-2 Mission

Scott Schoneman, Lou Amorosi, Mike Laidley, Kevin Wilder, and Bob Hunley Orbital Sciences Corporation, Launch Systems Group, Chandler, AZ, 85248

With their use of existing, flight-proven solid rocket motors, the Minotaur-family of launch vehicles have always been inherently suited to the quick reaction requirements of Operationally Responsive Space (ORS) missions. This capability was shown to be a reality by the launch of the TacSat-2 spacecraft on 16 December 2006 using a Minotaur I space launch vehicle (SLV). The Minotaur I successfully delivered the Air Force Research Laboratory (AFRL) TacSat-2 spacecraft to orbit – as well as the secondary NASA GeneSat-1 picosat –after being launched from the Mid-Atlantic Regional Spaceport (MARS) launch facility on Wallops Island, VA at the NASA Wallops Flight Facility (WFF). The lessons learned from this rapid response demonstration will be applied to further reduce the reaction time of the full family of Minotaur vehicles in support of future ORS missions. The TacSat-2 mission was a precedent setting realization of ORS launch capabilities, demonstrating a dramatic reduction in the normal mission integration, range interface, and field processing timelines. The launch took place less than 7 months after being initiated in late May 2006. It also demonstrated the ability to be prepared for launch in a stand-by configuration and launch when required after waiting ‘on alert’ for 5 days after being prepared to launch on 11 December. Moreover, all final operations from the start of spacecraft mate until launch were independently timed to assess the processing time that would be required in a true operationally responsive launch mode. The objective for this effort was to show the ability to respond within two weeks, with a goal of one week. The cumulative measured time for critical operations bettered both marks at less than 6 days of processing, showing that Minotaur vehicles are easily capable of meeting the launch requirements of ORS missions. In addition to achieving launch readiness in record time, the TacSat-2 mission also demonstrated a number of firsts. Most significantly, it was also the first launch from the MARS launch facility and was the first successful ground-based space launch from Wallops Island in 21 years. The TacSat-2 vehicle was the first Minotaur I to fly a larger, 61 inch diameter fairing and was also the first time a RocketCam on board video camera was flown on a Minotaur vehicle. Finally, the integration of the GeneSat-1 secondary pico-spacecraft was accomplished in a compressed schedule of less than four months.

Introduction Over the past several years, there has been an evolving realization that space assets need to be more responsive

to the warfighter on the ground. This overarching requirement has been consolidated under the banner of “Operationally Responsive Space (ORS).” This has culminated in the activation of an ORS office in May 2007 under the U.S. Air Force Space and Missile Systems Center (SMC) Space Development and Test Wing (SDTW) at Kirtland AFB, NM. In general, there are three fundamental elements that need to be addressed to increase the responsiveness of space assets: 1) Spacecraft, 2) Launch, and 3) Operations. Early on, there was significant emphasis on the second element – launch – to drive down the cycle time and cost. However, as the depth of understanding of responsive space operations has grown, the emphasis has shifted toward the spacecraft and operations. Part of this shift in focus can be attributed to the realization that existing launch vehicles are capable of supporting ORS, rather than having to start with the risks and significant investment of a clean-sheet design. Moreover, it has become evident that the lessons learned during the early development of Intercontinental Ballistic Missiles (ICBM) are similarly applicable to the responsive launch of spacecraft. In particular, launch vehicles based

AIAA SPACE 2007 Conference & Exposition18 - 20 September 2007, Long Beach, California

AIAA 2007-6145

Copyright © 2007 by Orbital Sciences Corporation. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.

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on solid rocket motors are preferable for some of the critical requirements needed for responsive launch: long term storage and rapid call-up to launch.

Relative to performance and launch vehicle size, the greatest focus of Responsive launch has been oriented

toward the class of launch vehicles capable of putting about 454 kg (1000 lbm) into LEO (185 km, 28.5 deg). This level was put forward by the requirements of the DARPA FALCON program and is easily met by the Minotaur I launch vehicle. However, later studies and analyses have indicated that somewhat great performance – up to roughly twice the DARPA FALCON requirements to LEO or smaller masses to Highly Eccentric Orbits (HEO) - may be desired meet some ORS objectives. For these cases, the Minotaur family provides a clear growth path via the Minotaur IV launch vehicle, while still maintaining continuity in many elements of vehicle design and integration.

The Minotaur family of launch vehicles thus provides a unique solution of responsive launch for the US military.

Not only are they currently available and utilize solid rocket motors, they combine flight-proven state-of-the-art small launch vehicle technology with the heritage of rapidly launched systems through the reuse of retired Minuteman II and Peacekeeper motors. This premise was further reinforced on 16 December 2006 when a Minotaur I space launch vehicle (SLV) successfully placed the TacSat-2 spacecraft into orbit after launching from Wallops Island, VA (Figure 1). This paper will go into detail about how this was accomplished and why it was a demonstrable step towards truly achieving ORS objectives, as well as covering some additional developments since the TacSat-2 launch.

Minotaur Family The Minotaur family includes the Minotaur I, IV, and V space launch vehicles (SLV’s) and Minotaur II and III

suborbital or Target Launch Vehicles (TLV’s), as shown in Figure 2 along with their performance to typical orbits or trajectories. These vehicles are currently available via the Orbital Suborbital Program (OSP) contract, under the USAF Space and Missile Systems Center (SMC) Space Development and Test Wing (SDTW). The OSP contract was competitively awarded to Orbital originally in 1997 with a follow-on 10 year contract again competed and

Figure 1 - Minotaur I Launching TacSat-2 from Wallops Island, VA In a Demonstration of ResponsiveLaunch Capabilities

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awarded in 2003. Via OSP, Minotaur vehicles supply a proven combination of the reliability of both decommissioned, Government-owned boosters and Orbital’s commercially-based hardware and practices. From the beginning, the requirements of the OSP program have stressed system reliability, transportability, and operation from multiple launch sites requiring minimal infrastructure. These characteristics directly facilitate the application of the Minotaur launch vehicles to the ORS launch mission. In addition to the reliability and responsiveness benefits, the use of decommissioned motors also provide a best-value to the US Government, provide realistically low-cost – and ultimately best value - launch vehicles. More information on the heritage of the motors and systems is included in the Appendix.

Figure 2 - Minotaur Family of Launch Vehicles

The Minotaur I space launch vehicle had its first launch in Jan 2000, successfully delivering five spacecraft to orbit. The sixth mission, in December 2006, was the TacSat-2 mission which is the focus of the detailed discussion below. There have now been seven launches at this writing. The most recent mission was the launch of the Near Field Infrared Experiment (NFIRE) spacecraft for the Missile Defense Agency (MDA) on 24 April 20071. Over this septet of launches, the ability of the Minotaur I to accommodate a variety of mission requirements has been demonstrated. Almost half of the missions have flown multiple payloads resulting in a total of 17 spacecraft being delivered to orbit by Minotaur I – the total is 25 spacecraft if eight picosats subsequently separated from carrier spacecraft are included – to seven different orbits. Six different separation system designs have been used for primary payloads plus several others for secondary spacecraft. Two different payload fairings have been demonstrated. And launches have been conducted at two different launch ranges – Vandenberg AFB on the West Coast and Wallops Flight Facility on the East Coast – which included the design, installation, and activation of basic launch access towers at both locations.

All together, there have been fourteen launches of vehicles in the Minotaur family: seven Minotaur I SLVs and

seven Minotaur II suborbital TLVs (Figure 3). Because the functional architecture and systems – such as avionics, controls, software, flight termination system (FTS) analytical methodology, test/launch consoles, and integration & test practices – are shared across the Minotaur family, this combined flight experience is applicable to all Minotaur vehicles. Minotaur IV SLV benefits from the responsive launch lessons of Minotaur I allowing it to meet the requirements of the larger responsive payloads. Moreover, there have been modifications developed to support

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rapid targeting and operations of the Minotaur II that have direct benefit to responsive space launch of Minotaur I and IV.

A. Responsive Launch History Before TacSat-2, Minotaur II had served as the test bed for incremental steps in achieving different elements of

responsive launch. On the second Minotaur II mission – and the first operational launch in support of MDA testing – the vehicle was prepared and made ready at the launch site as a four-day call-up backup to the final launch of the predecessor Multi Service Launch System (MSLS) rocket from Vandenberg Air Force Base (VAFB), CA. After the successful launch of the final MSLS, the Minotaur II vehicle was then put into a stand-by mode, remaining in the silo and awaiting the next call-up. This served to help the team learn and practice the processes required to maintain a vehicle on alert over a period of time. The Minotaur II remained in this on-alert state for five months, after which the launch crew returned to VAFB and successfully launched the vehicle after an abbreviated two week field campaign. It is also worth noting that the two week response was driven by range safety and customer preparations and rehearsals, not by launch vehicle limitations. A recent Minotaur II launch on 20 March 2007 demonstrated the ability of the Minotaur vehicles to rapidly recycle after an abort late in the countdown. With less than two minutes remaining in the count, a downrange asset went “red” and called an abort. After resolving the situation, coordinating a new launch time among several participating assets, , and recycling the entire operation, the Minotaur II was launched less than an hour after the original abort was called.

More recently, Minotaur II vehicles have been adapted into a new configuration – Minotaur II+ - as targets for

the NFIRE spacecraft to observe. The first of these targets was launched on 23 August 2007 from Vandenberg AFB, one day short of four months after the spacecraft was launched on a Minotaur I. The objective of the exercise was for the NFIRE satellite to collect high and low resolution images of a boosting rocket which will improve understanding of missile exhaust plume observations and plume-to-rocket body discrimination2. To support this objective, the Minotaur II flew within 3.5 km of the spacecraft in its orbit3. To do this naturally required technology that allowed precise targeting and launch timing, which is directly applicable to the need for rapid targeting of ORS concepts. It was developed and demonstrated in the lab and during factory integration testing on the flight vehicles and now has been demonstrated on a highly successful launch. A second such Minotaur II+ is being prepared for a

Figure 3 - Minotaur I and II Have A Combined History of 14 Successful Launches

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similar test. The unique nature of the mission also drove key discussions and resolution with range personnel regarding the unique requirements of these ORS-type Minotaur operations.

B. Successful Heritage and Future

Minotaur launch vehicles draw on the long, successful track record of the USAF’s Rocket System Launch Program (RSLP), which is now part of the SDTW Launch Test Squadron (LTS). For decades, they have specialized in the use of decommissioned motors for various suborbital missions, much of which has been done in conjunction with Orbital. RSLP also became become the focus for DoD small launch vehicle services. They entered into the small space launch area in the mid-90’s when they took on the management of the USAF Small Expendable Launch Vehicle Services (SELVS) program. This contract covered DoD use of Orbital’s Pegasus space launch vehicles (SLV). In 1995, RSLP also took over the Standard Small Launch Vehicle (SSLV) project from the Defense Advanced Research Projects Agency (DARPA), adding Orbital’s Taurus vehicle to their capabilities. The DARPA SSLV had set the stage for utilizing decommissioned Government-owned solid rocket motors for reducing the cost of space launch by using decommissioned Peacekeeper (PK) Stage 1 motors , starting with the first Taurus mission of the STEP 0/DARPASat spacecraft in 1994. Subsequently, RSLP initiated the OSP contract in 1997, providing RSLP with an SLV specifically designed to utilize decommissioned Minuteman ICBM motors in conjunction with state-of-the-art commercial subsystems and practices. This vehicle was subsequently dubbed “Minotaur I.”

Minotaur I and II - The Minotaur I SLV, such as was used for the TacSat-2 mission, (Figure 4) and Minotaur II

TLV (Figure 5) both make use of decommissioned Minuteman II boosters. Minotaur I uses the first two Minuteman stages, whereas Minotaur II uses all three stages. For Minotaur I, the two GFE stages are combined with the upper two stages, structure, payload fairing, and several core subsystems shared with Orbital’s Pegasus SLV. The heritage components have been enhanced with newer, modular avionics components and new object-oriented flight software

to increase flexibility, reliability, and responsiveness. This OSP-standard avionics and software is also used on the Minotaur II - and all of the other Minotaur family of vehicles - as is the electrical ground support equipment (EGSE) consoles. This allows extensive commonality between all OSP vehicles, allowing standardization of integration and test, as well as field integration and launch operations, thereby increasing overall efficiencies. Moreover, this basic OSP architecture has now been adopted on new Orbital launch vehicles, thereby allowing the improvements and lessons of multiple programs to be gleaned by the Minotaur vehicles. Most critically, the OSP architecture has been adopted for use in missile defense interceptor applications. As a result, the improvements relating to the responsive launch requirements for interceptors can be readily applied to the Minotaur vehicles.

Figure 4 - Minotaur I SLV for TacSat-2 Mission on Pad 0B at Wallops Island, VA

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The total development time from initial to first launch of Minotaur I and II vehicles was less than 28 months and 21 months, respectively. The initial demonstration of this Minotaur-family architecture occurred on the inaugural Minotaur I launch on 26 January 2000, successfully launching the Joint Air Force Weber State Satellite (JAWSat) from Vandenberg AFB, CA. This was followed up within the next six months by the demonstration mission of the Minotaur II TLV on 28 May 2000 and the second Minotaur I SLV mission, MightySat II.1, on 20 July 2000.

Minotaur III and IV - The Minotaur III and IV utilize

decommissioned Peacekeeper solid rocket motors, versus the Minuteman II motors used for Minotaur I and II. Minotaur III is a suborbital target launch configuration whereas Minotaur IV is the space launch configuration. The Minotaur IV vehicle design is shown in Figure 6, highlighting the minimal number of ‘new’ subsystems and components required. In fact two components previously identified as ‘new designs’ are no longer required due to changes in how the OSP architecture is interfacing with the PK boosters. Performance predictions have not changed

Figure 5 - Minotaur II TLV in LF-06, VAFB, CA

Figure 6 - Minotaur IV SLV is Composed of Mature, Flight Proven Subsystems and Designs

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from the original proposal values. This is due to the appropriate management of mass properties margins, based on Orbital’s extensive history in developing new small launch vehicles.

Both vehicles share their basic structures and avionics, with the primary difference being the 4th stage

propulsion systems used. Minotaur III has a monopropellant hydrazine system for the precise delivery of target applications, whereas Minotaur IV utilizes an Orion 38 solid rocket motor as an orbital insertion stage. A growth configuration, Minotaur IV+ uses the larger Star 48BV in place of the Orion 38 to provide higher performance. The commonality between the two designs provide efficiencies in the development effort, as well as in hardware procurement and integration The development of the Minotaur IV space launch vehicle has been proceeding well, meeting all schedule commitments to date in support of the Space Based Space Surveillance (SBSS) mission. At the onset, the Air Force initiated a number of risk reduction efforts to provide early retirement of all the initial risks that were identified. Given the extensive use of flight-proven elements in the Minotaur III and IV vehicles, there were a relatively small number of items to address.

TacSat-2 Responsive Launch Demonstration The TacSat-2 mission was sponsored by the AFRL as part of the Operationally Responsive Space (ORS)

initiative being organized within the DoD. It was the first launch of a planned series of TacSats designed to demonstrate technologies critical to providing rapid, dedicated space-based support of operational forces on the ground. As part of this effort, the mission was the first successful launch directly oriented at demonstrating requirements related to ORS.

C. A. Mission Overview The primary goal of the TacSat-2 mission was to launch the AFRL TacSat-2 Space Vehicle (SV) into low-earth

orbit to provide an on-orbit demonstration on high-payoff space system technologies. TacSat-2 provides on-orbit testing for emerging technologies to ensure their readiness for ORS missions. The Air Force selected the launch location for this mission to be Wallops Flight Facility (WFF), Wallops Island, VA. Figure 5 is a photo of the TacSat-2 spacecraft prior to it being mated with the launch vehicle at Wallops.

The TacSat-2 demonstration had three main objectives. 1. Rapid design, build and test of a launch ready space vehicle within 15 months from authority to proceed. 2. Responsive launch, checkout and operations to include launch in the shortest time possible from

encapsulation, performing an on-orbit check out within one day, conducting lean operations and downlinking data directly to the theater.

3. Militarily significant capability to include obtaining images with tactically significant resolution and provide them directly to the theater.

The official TacSat-2 contract order was executed with Orbital Sciences Corporation on 12 May 2006. The

original launch date was just six months later, on 15 November 2006. This quick response was made feasible by the availability of hardware that was originally intended for other launches that had been delayed, freeing up the

existing components to support the TacSat-2 mission. However, although the components and subsystems were available, the normal 18 month mission and range integration activities had to be accomplished within 6 months as well as the vehicle still had to be assembled, tested, and verified to meet the TacSat-2 requirements.

Due to the shortened schedule, a combined Mission

Design Review and Launch Vehicle Pre-Ship Review was held on 13 September, 2006. Shortly thereafter, AFRL indicated that additional time was needed to test the SV prior to shipping to the launch site and set a new launch date of 11 December 2006. All of the required launch vehicle and space vehicle flight hardware and support equipment was then shipped to WFF. As previously mentioned, this was the first use of these Wallops facilities and interfaces by

Figure 5 - TacSat-2 Spacecraft During Final Integration at Wallops Island

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the Orbital team and the AFRL team. However, due to thorough preplanning and a focused, experienced crew, all integration activities proceeded smoothly and on schedule. Checkout was performed by the Orbital team and the AFRL team on their respective elements of this mission. The space vehicle was mated with the Minotaur I integrated Stage 3 and Stage 4 assemblies and the new 61 inch fairing encapsulated the spacecraft to complete the Upper Stack Assembly (USA). The USA was then moved to the launch pad for integration with the Minuteman motors that make up the Lower Stack Assembly (LSA).

Final checkouts were performed and the Minotaur rocket was in a launch ready state on 11 December 2006.

Following a five day slip to investigate and correct concerns with the TacSat-2 SV software configuration, the launch occurred on 16 December, 2006 - less that seven months form contract turn-on. During the last five days, the vehicle remained ‘on alert’ on the launch pad, ready to go directly into the launch countdown when called upon. Although not planned, this was additional demonstration of ORS capability, illustrating the ability of the Minotaur I launch vehicle to remain in a launch-ready “alert” state for an extended period of time. It was maintained in ready state, waiting for immediate direction to launch versus having to worry about the complexities of defueling, refueling, and maintaining liquid propellant supplies. Ultimately, the final call-up approval was received just the day before launch.

After receiving direction to proceed for a new launch date of 16 December, the integrated Orbital/Air

Force/NASA launch team picked up operations essentially where they had been stopped when the original 11 December launch was scrubbed. The countdown was initiated per the Launch Checklist at 02:00:00 EST, targeting a nominal launch time of 7:00:00 EST (350:00:12:00.000 UTC). There were no significant spacecraft, Range, nor launch vehicle issues reported throughout the count. The Final Launch countdown checklist was initiated at T-60 minutes and continued nominally with no significant issues nor waivers. Liftoff occurred at 07:00.00 EST (350:12:00:00 UTC) – precisely at the opening of the launch window. After liftoff, all mission events proceeded nominally throughout flight within prelaunch predictions. Good telemetry data and RocketCam video was received throughout the flight, allowing detailed post flight evaluation which further confirmed the flawless operation of the Minotaur I launch vehicle. The TacSat-2 was delivered and separated well within the defined orbital accuracy requirements, as shown in Table 1. The required accuracy was tight for an all-solid stage launch vehicle, yet the Minotaur delivered precision was well within even these tight requirements.

Table 1 - Minotaur I Orbital Accuracy Was Well Within TacSat-2 Requirements

Orbital Altitude

Insertion Apse

Non-Insertion Apse

Inclination (deg)

Accuracy Relative to Nominal Requirement: + 3 km +14 km 0.01°

D. Multiple Mission “Firsts” on TacSat-2 Increased the ORS Challenge Adding complexity to the shortened schedule were several vehicle and mission first flight items. They included

the usage of a new hammerhead 61-inch fairing, significantly altering the vehicle aerodynamics and structural loading as well as ground operations. The fairing also included a new separation system and new acoustic blankets. Further complicating matters was the fact that TacSat-2 would have to use the qualification fairing in order to achieve the 6 month schedule, a fairing that had been damaged and subsequently repaired. It was unknown if the repairs would cause any issues. So within the 6 months, the fairing was thoroughly tested and inspected to assure its structural integrity. This was one of the primary critical path items for the TacSat-2 mission, but was successfully accomplished and the fairing was made ready for flight.

Another critical ‘first flight’ item was the launch range itself, being that TacSat-2 would be the inaugural launch

from MARS commercial spaceport facility at Wallops Island as previously mentioned. Although some preliminary coordination had been in work for another Minotaur launch, there was a large amount of effort required to actually prepare for launch. New procedures had to be provided to the Range - and then reviewed and revised. It was also the first use of the facilities for a live Minotaur I launch, so the details of operations, procedures and modifications had to be quickly worked out and completed All of this was completed, even though the Minotaur I was the largest vehicle ever to successfully launch from the Wallops Flight Facility. To mitigate the risk of building up at a new

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location, it was decided to perform a full series of electrical test and stage mates (fit checks) following the Orion booster processing at Orbital’s Vehicle Assembly Building (VAB) at Vandenberg Air Force Base (VAFB). This required the shipment of the EGSE and Upper Stack hardware to Vandenberg prior to proceeding to Wallops.. This process took additional time to ship, assemble, test, disassemble, and then ship the hardware across country. Having successfully proven the ability to fully process at WFF, this intermediate step has been eliminated for future non-VAFB launches.

On top of these accelerated nominal preparations for launch, it was also decided after the mission had been

initiated to fly NASA’s GeneSat-1 picosat as a secondary spacecraft. The integration of GeneSat-1was accomplished even more rapidly than the TacSat-2 integration, going from ATP to launch in only four months. GeneSat-1 was developed by NASA Ames Research Center. The Small Spacecraft Office at NASA Ames teamed with industry and local universities to develop GeneSat's fully automated, miniature spaceflight system that provides life support for small living things. GeneSat-1 utilized a standard CubeSat design that has been developed to facility such picosat opportunities (www.cubesat.org). Although multiple CubeSats have been launched on foreign launch vehicles, GeneSat-1 was also the first CubeSat-based spacecraft to fly on a domestic U.S. launch vehicle. The GeneSat-1 spacecraft was deployed from a CubeSat launch 'pod' that protects and ejects the satellite(s) once in orbit. This deployment mechanism - the Poly-Picosat Orbital Delivery System (P-PODS) – was designed and built by students at the California Polytechnic State University at San Luis Obispo. Stanford University participated in the spacecraft design and mission operations were handled by Santa Clara University.

The TacSat-2 launch was also the first Minotaur vehicle to fly a RocketCam onboard video camera, which

recorded the spectacular early morning liftoff and ascent. All of these “first flight” items were all accomplished in the shortened mission integration time, making this ORS demonstration all the more significant.

E. Responsive Launch Timing Demonstration In support of the planned ORS demonstration elements of the TacSat-2 mission, the Air Force requested that the

final launch integration efforts be measured as a baseline of current integration and launch capabilities. Therefore, a requirement was imposed on the launch vehicle organization to evaluate the time taken during the final processing from the start of final spacecraft mating through launch. Specifically, the language in the contractual Mission Requirements Document (MRD) was:

“Launch Vehicle Contractor (LVC) will have the goal of demonstrating a responsive launch capability. The goal is to launch one week after payload encapsulation, the objective is 2 weeks. 3 weeks is not desirable, but acceptable. The LVC shall track the actual event times between encapsulation and launch to perform an analytical timeline to complete all activities. This timeline, assuming 24 hours per day, will be used to assess the responsive launch capability. This timeline demonstration will not be a part of the mission success criteria for this mission. The point of encapsulation is when the fairing is installed thereby limiting access to the payload.”

Coordination meetings were held between Orbital, Air Force Space Command (AFSPC) and ORS personnel to identify which operations would be necessary for an ORS call-up, versus what items were for normal maintenance, training, or other ORS logistical activities. For example, the countdown dress rehearsal which typically occurs several days prior to launch was considered a sustainment activity since it would be handled via regular training of the launch crew, including Range support. Similarly, there are nominally several final readiness reviews that are decision points to proceed with the launch operation. In an ORS scenario these would be condensed down to a single operational command authority to give the ‘go’ for launch. Ultimately, the ‘hands on’ efforts needed to prepare the vehicle for launch were the core of the critical processes identified, which are listed in Table 2.

As shown in Table 2 and Figure 6, the results indicate that the final processing could be achieved in a cumulative

time of 6 days, beating the most stringent goal of 7 days. As mentioned previously, the procedures were not optimized or specially rehearsed to minimize the time involved. This was particularly true in the case of the fairing encapsulation, which reflected the initial flight use of the AFRL 61 inch fairing, as well as the first Minotaur operation conducted at the Wallops Flight Facility. Therefore, the results can be considered conservative, allowing for margin for unknowns that might crop up during actual 24/7 operations in support of an ORS mission.

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Procedure Description MinutesSWP18-0006 Payload Mate 184WP18-0030 Upper Stack Ordnance Connections 960WP18-8030 Lower Stack Emplacement 340WP18-9010 Thermal Cover Installation 165AF TO Lower Stack Transport & Tie Down 180WP18-0041 Fairing Installation 2275WP18-0055 Shear Pin Installation 390WP18-0118 MMODS (FTS) Installation 1020WP18-2401 Lower Umbilical 210WP18-0063 Transfer Upper Stack Into T.E. 540WP18-0061 Upper Stack Transportation 17WP18-0062 Upper Stack Emplacment 630WP18-8040 Rate Gyro Installation 420WP18-2403 Post Stack Verification Test 240WP18-2412 Range Interface Test 180WP18-0035 FTS S/S and FCDC Connections 90WP18-2415 FTS End to End Testing 120WP18-0070 L-1 Closeouts 375WP18-2507 Launch Operations 300Total Minutes 8636Total Hours 143.9Total 24 Hour Days 6.00

Electrical

Mechanical

Launch Ops

Combined

Legend

Table 2 - Timing of Processes from Spacecraft Mate Through Launch Demonstrated That 6 Day Response is Currently Achievable

Figure 6 - Final Integration from Spacecraft Mate Through Launch Were time to Determine Baseline Minotaur I Responsive Capability

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Additionally, although the timeline evaluation would assume 24/7 operation, the addition of the three shifts of crews to support this was not within the scope – and budget - of the TacSat-2 effort. Therefore, it was agreed that the operations would be timed as they were conducted on standard single-shift operations with the total time then summed to determine the cumulative duration that could be achieved assuming 24/7 processing. Table 2 shows the operations list and the times required to perform the critical activities. Figure 6 shows the same final processing timeline in a flow chart format. Further, because of the short overall mission duration from turn-on to launch and limited budget, it was not feasible to add in any significant refinement of either the processes or the vehicle design.

Minotaurs for Responsive Launch: The Next Steps To achieve the quick-reaction requirements of ORS, a reasonable amount of maturity is required in the launch

vehicle design and the processes involved in its preparation. The TacSat-2 mission was the sixth Minotaur I vehicle and as such benefited from over six years and five vehicles worth of process maturity. Five additional launches of the Minotaur II suborbital configuration also contributed to this maturity due to large amount of commonality and standardization across the Minotaur family, including management and personnel in addition to core vehicle elements such as avionics, software, and ground support equipment. Moreover, these elements must be focused on the overarching goal of mission success. Only after the processes and procedures have been demonstrated to thoroughly and rigorously control the build and integration process can they be realistically optimized to achieve responsive timelines.

As mentioned previously, the launch of the TacSat-2 vehicle in less than seven months was possible because the

availability of most of the vehicle components from existing inventories. Most of this hardware had been built for other missions and was available for use because of delays driven by funding constraints, creating a unique opportunity to demonstrate Minotaur’s responsive capabilities. The readiness of the TacSat-2 spacecraft was also vital, as they were able to provide detailed models and interface details as the initiation of the process. Even though the TacSat-2 mission was assembled from various elements that were not originally focused on ORS requirements – largely because they predated the conception of ORS – the Minotaur I was able to support the mission on a compressed timeline largely because of the maturity of its design, processes, and organization. Given this, significant improvements in responsiveness are possible with additional forethought and planning, without requiring major launch vehicle design changes.

It should be noted that the Minotaur program continuously refines and improves the overall heritage process

flows now used for fourteen successful launches with seven more in work. These changes have primarily come in the form of lessons learned, which is a standard part of Orbital’s business philosophy and will continue into the future. Based on this experience, the overall operations required to process the launch vehicle up to the point of spacecraft mate are currently fairly well optimized to provide both efficiency and reliability. Therefore, most process optimization prior to this point (spacecraft mate) will primarily be in the form of refinement of specific operations or tasks.

One key to improving the efficiency of any process is standardization. Optimizing the launch process is no

different. Every Minotaur I vehicle flown has had a unique set of requirements, comprised of various orbits, mass properties, separations systems, launch sites, and/or optional payloads. Each unique mission requirement drives an expanding series of derived requirements that must be addressed first by engineering, then by integration and test, and finally by the launch team. The first step to succeeding at ORS is to define overall mission objectives, bound mission requirements establish common interfaces between the launch vehicle and spacecraft, and define the limits of spacecraft properties (size, mass, stiffness, etc.). Once these system requirements are set, the vehicle design can be optimized to accomplish the required missions through the most efficient path possible.

In particular, further reductions in operationally responsive timeframes are possible through the incorporation of

strategic development efforts to improve efficiency, automation, and standardization. As was the case with the TacSat-2 mission, it is vital to have the launch vehicle –and spacecraft – as far along in their integration process as possible to minimize the response time to launch. Therefore, to truly achieve responsive launch, the launch vehicle must be procured and integrated in advance of their need, rather than the more typical reactive procurement. Moreover, the commitment to building launch vehicles in quantity will also provide significant cost advantages compared to the status quo unitary production. Building launch vehicles in production lots using common avionics and structures improves not only the financial costs of the space launch but also optimizes the quality. Testing

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multiple sets of hardware to common procedures provides a vetting process which weeds out design errors, manufacturing defects, and workmanship issues. Although the projected quantities needed to support ORS (in the order of magnitude of 10’s) may not approach a true “production line” rate (100’s to 1000’s and above), building even several vehicles consecutively moves the effort up the steepest part of the learning curve, thereby giving substantial benefits even at low volume. This has even been demonstrated on the OSP program when several Minotaur II vehicles were built in quick succession, Orbital achieved efficiencies that resulted in funds being reimbursed to the Air Force because of under runs in the final cost. Moreover, actual results from production of launch vehicles similar to Minotaur I - in the form of the Orbital Boost Vehicle (OBV) GMD missile defense booster – have shown dramatic reduction in manufacturing labor as the production ramped up from the first unit to five to ten vehicles.

One of the areas that currently requires a significant amount of customization and reiteration is the generation of

flight software for a given mission. As a result of the traditional mission-specific approach, the trajectory is developed as a “point design’ supporting the unique requirements of the particular spacecraft. Therefore, this is a prime area to address in improving overall mission response time. Automating the trajectory design process will provide responsive targeting of the launch vehicle, minimizing labor and expediting the delivery of trajectory data for Range Safety analyses. The standardized definition of spacecraft mass properties and orbital requirements within an envelope of reasonable accuracy and precision, versus a specific point design, will allow the launch vehicle to develop predetermined trajectories for use in truly rapid responsive space launch requirements of weeks or less. While launch ranges will need to approve all trajectories and provide safety corridors for launch operations, this process must be streamlined through the standardization of requirements. The development of an integrated range tracking, telemetry relay, and command destruct communication system would greatly reduce the range coordination activities and improve responsiveness. Delving deeper into the area of Range Safety coordination is beyond the scope of this paper, but it must be acknowledged as a vital piece of the responsive launch solution.

In addition to the trajectory and flight software development, another effort that currently involves a significant

amount of “hands on” labor is the thorough testing of the launch vehicle. Similarly, the current labor-intensive state is driven by the one-off nature of the status quo. When only one vehicle is being processed at a time – with unknown total quantities and follow-on missions – it is not cost-effective to put extra effort towards automation. However, as quantities increase and production levels are known beforehand, the extra investment to automating testing becomes worthwhile. Symbiotically, this also contributes towards launch responsiveness through the design of built in test capabilities into the avionics, flight control systems, and ground support equipment. A relatively small amount of non-recurring engineering could significantly reduce the maintenance costs of the vehicles being maintained in the responsive pool, as well as expediting their final check-out and launch.

The Minotaur I launch vehicle currently uses integration CONOPS that do not require much specialized

equipment, including multiple crane lifts to integrate the launch vehicle on the pad, but at the compromise of expediency. The timeliness and weather considerations of this activity could be significantly improved with the development of an integrated vehicle transportation system – a Transporter Erector (TE) which could operate in high winds and lift the entire vehicle on the launch pad in one operation.

Ultimately the question that must be asked is how responsive does the system need to be to support the

Government’s ORS needs. The answer to this question will drive different levels of optimization (and maintenance) for the responsive launch vehicle fleet. A 24 hour callup requirement between activation and launch would require investment in automation and facilities to achieve. Meanwhile, a seven day callup can be achieved with standardization of the payload and orbital requirements along with a relatively simple optimization of current vehicle processing standards. A thirty day callup would further reduce the level of complexity associated with vehicle maintenance and launch range process modification.

A sustainment cost must also be factored into each of the above scenarios to comprehensively evaluate overall

costs versus the benefit of different call-up times. Sustainment activities include vehicle maintenance, launch crew rehearsal drills, integrated command and control rehearsals, readiness reviews, etc. These activities would ensure a true ORS capability.

In a true ORS CONOPS, it is recommended that additional vehicles of the same configuration be procured and

built in parallel to facilitate rotation of vehicles for periodic maintenance. Limited life components will require

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additional hardware procurements to support service life extension testing and some components may require replacement, upgrades, or even modification for future ORS applications. .

Conclusions Through the TacSat-2 mission, the feasibility of Minotaur launch vehicles to realistically and reliably support

ORS launches has been demonstrated. The mission demonstrated multiple incremental steps toward a truly responsive launch capability, even without any system design or operational changes and while also achieving multiple ‘firsts.’ In addition to the launch vehicle being fully integrated and prepared for launch in less than seven months, the capability to remain on alert in a launch ready posture was serendipitously demonstrated due to a late slip in the requested launch date. Through timing of the critical operations from spacecraft mate through launch, it was shown that a 6 day response is currently available by simply going to 24/7 operations in the end game.

The TacSat-2 mission demonstrated that extensive development of a new or highly modified vehicle is not

required. The ability of Minotaur launch vehicles to meet ORS requirements in the very near term is directly correlated to the maturity of the system designs, as well as the depth of experience of the combined Air Fore and Orbital organizations. This provides an existing, cost effective, and reliable capability for ongoing support of ORS and other Government-sponsored space launches. With just minimal adaptations and modifications to the existing systems and processes focused on specific responsive launch requirements, short call-ups are feasible. Further reductions in launch response time can be readily achieved by standardization of the mission integration elements, such as spacecraft interfaces, and advanced procurement of launch vehicles. Extensive development of a new or highly modified vehicle is not required – just minimal adaptations and modifications to the existing systems and processes focused on specific responsive launch requirements. Finally, this capability is also directly transferable to the larger Minotaur IV SLV, providing the capacity to support larger spacecraft, multiple manifest mission, and specialized orbits such at highly eccentric orbits (HEO) that may also be part of the ultimate ORS solutions.

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Appendix A-1. Minuteman and Peacekeeper Heritage Systems

The foundation of the Minotaur-family vehicles is the use of boosters from decommissioned Minuteman II and Peacekeeper (PK) ICBMs. Because these vehicles were designed to be at the vanguard of the U.S. strategic forces, they are inherently designed for reliability and longevity. Moreover, they are specifically designed to be storable and responsive – characteristics that were vital in the ICBM role, needing to launch in a matter of minutes when called upon.

The Minuteman II system has its origins in late 1950’s when Air Force research indicated that a solid-fuel

system was technologically feasible4. The burgeoning solid fuel technology gave it significant advantages over the original liquid-fuel launch vehicles of the time. A solid fuel system was desired because it provided a much higher reliability, lower maintenance and the ability to be stored for longer periods of time. Unlike a liquid fuel system, which required fueling and/or other preparations before launch, the Minuteman system was capable of being launched within second of activating the launch sequence. Similar logic makes solid fuel rockets preferable for the responsive launch solution. Moreover, solid propellant systems are generally considered to be safer than liquid systems when properly handled, particularly for long term storage and rapid launch. They do not require the storage, handling, and fueling of volatile, combustible liquids nor hazardous cryogenic fluids. This safety advantage of solid propellant systems has been confirmed by their use on all modern major missile systems, small to large, and by all military services.

The first test flight of a Minuteman I system occurred in Feb 1961 from Cape Canaveral, Florida and was

successful. The first Minuteman I vehicles were on operational alert by Oct 1962. The Minuteman II, with a new, higher performance 2nd stage motor was first launched in Sep 1964 and the Minuteman III, with an new Stage 3 motor, was first launch in August 1968. All told, there have been 838 Minuteman-based launches of which 816 have been successful for an overall success rate of greater than 97%5. This value includes early developmental failures in the 1960’s. The unmodified Minuteman II boosters that are used for the Minotaur vehicles have an unprecedented success rate of 100%: 198 of 198 launches3. These numbers include the twelve Minuteman II-based RSLP launches under the OSP program, as well as the eight launches under the predecessor Multi Service Launch System (MSLS) program.

The PK system has a similar highly successful history, starting with the first test launch in June 1983 (Figure A-

1). Although the total numbers are not as large, PK boosters have a 98% success rate of 50 successful launches out of a total of 516. (53 of 54 counting the three Taurus launches which used the PK Stage 1 motor). This launch history is supplemented by multiple static firings of each stage: 20 for Stage 1, 18 for Stage 2, and 18 for Stage 3. Moreover, the one failure of a PK booster was not caused by an element that is being used for the Minotaur III or IV.

The overall combined success rate of the PK and MM II boosters used for the

Minotaur vehicles is greater than 99%. This contrasts quite dramatically with the success rate of the liquid fuel ICBMs of similar origins: 74% (168 of 228) for Atlas (A thru F)7, 71% (53 of 74) for Thor8, and 70% (47 of 67) for Titan I9. Titan II has the best record with an 81% success rate (66 of 81)10, but it still falls substantially short of the solid-motor MM and PK vehicles. Note that these values reflect only the ICBM application of these boosters to give a representative comparison of the fundamental booster reliability in a responsive roll. For the space launch derivatives, particularly in the case of the Gemini launches on Titan II, significant extra scrutiny and effort was applied to assure success, but also with correspondingly reduced responsiveness. Although some have characterized this use of decommissioned motors as the Government taking away business from the commercial launch vehicle industry, this is not the case. In reality, it allows the Government to make use of its valuable existing assets – reliable, decommissioned motors – rather than paying to have them destroyed. Overall, more than 90% of the funding for OSP launches goes to commercial contractors via competitively

Figure A-1 - PK Test Launch, VAFB, CA

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awarded contracts. Additionally, the OSP launches are contracted on a fixed-price incentive firm (FPIF) basis, thereby limiting the Government’s liability to unexpected cost overruns. The prices are also fully audited and negotiated with the Government, assuring their accuracy.

A-2. Minotaur as Test-Platform In addition to providing cost-effective launches, the Minotaur family of vehicles has also served successfully as a

platform for testing out new launch vehicle technology in a expedient manner. Experiments, technology demonstrations, and other “firsts” have been a part of most Minotaur missions. Among these are a GPS Postion Beacon (GPB) providing autonomous metric tracking for Range safety, a Low Cost TDRSS Transmitter (LCT2), and an advanced grid-stiffened composite fairing. The first two, in particular are pertinent to ORS applications. By providing autonomous tracking and a satellite-based telemetry link, the need for Range support infrastructure, such as downrange telemetry antennas and tracking radars is greatly diminished. Also, this simplifies operations by reducing the number of sites and systems involved, similarly improving the ability to react and launch in a responsive manger. These are each discussed briefly below and shown in Figure A-2.

• GPS Metric Tracking. A GPS Position Beacon (GPB) system has been demonstrated on two Minotaur I missions. The inaugural JAWSat mission successfully flew a second generation of Orbital’s GPB. More recently, the third mission, XSS-11 in April 2005, flew the latest technology fourth generation GPB-IV system. The data from this flight has been certified by Range Safety engineers at the Western Range, as one of three flights necessary to validate the GPB-IV for Range Safety use.

• Low Cost TDRSS Transmitter. On the fifth Minotaur I launch, a NASA-developed Low Cost TDRSS Transmitter (LCT2) was flown. It worked flawlessly, delivering real-time telemetry throughout the mission via the TDRSS link. This system is much less costly that previous TDRSS transmitter solutions and avoided the need for the expense and complications of downrange telemetry receiving sites.

• Grid-stiffened Composite Fairing. The TacSat-2 launch was the first mission to fly a larger, 61 inch diameter fairing that was jointly developed by AFRL and Orbital. It used an innovated fiber-layup manufacture to create a grid-stiffened design from composite fiber construction.

1 MDA Press Release 07-NEWS-0031, Missile Defense Research Satellite Launched, 24 Apr 07 2 MDA Press Release 07-NEWS-0043, Missile Launch to Support Boost Phase Data Collection Experiment Successfully Completed, 23 Aug 07 3 General Dynamics Press Release, General Dynamics-built NFIRE Satellite Successfully Completes First Missile Defense Experiment, 23 Aug 07 4 Neufeld, J., “The Development of Ballistic Missiles in the United States Air Force 1945-1960”, Office of Air Force History, United States Air Force, Washington, DC, 1989. 5 Web Page: http://www.geocities.com/minuteman_missile/ launches.htm 6 Web Page: http://www.geocities.com/ peacekeeper_icbm/launches.htm 7 Web Page : Gunter’s Space Page – Atlas ICBM: http://www.skyrocket.de/space/doc_lau/atlas_icbm.htm 8 Web Page : Gunter’s Space Page – Thor IRBM: http://www.skyrocket.de/space/doc_lau/thor_irbm.htm 9 Web Page : Gunter’s Space Page – Titan I ICBM: http://www.skyrocket.de/space/doc_lau/titan-1.htm 10 Web Page : Gunter’s Space Page – Titan II ICBM: http://www.skyrocket.de/space/doc_lau/titan-2_icbm.htm

Figure A-2 - - Minotaur I Has Been Utilized to Demonstrate New Launch Vehicle Technologies

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