Chapter 3
National Spacelift System Capabilities

No one can predict with certainty what the ultimate meaning will be of the mastery of space. (It may) hold the key to our future on earth.

-President John F. Kennedy

Using the horizons mission methodology, the 2025 spacelift architecture is an emerging third generation system that has take advantage of technology advances since the early 1990s. The systems characteristics and core competency missions are described in the 2025 environment, and notional progress is shown from first through second generation systems. Propulsion is described in detail in the appendix, because it is the pivotal technology push required for success of the system. The progress to 2025 occurs in three distinct steps: a first generation system exploiting current propulsion technologies, structural composite advances, and low-cost technology reusable demonstrators; a second generation system integrating evolutionary/revolutionary advances in conventional chemical propulsion, technological advances in structures and computers, and refinement of the first generation operational system; and, finally, an emerging third generation system performing all required lift and mission requirements with refinements in second generation propulsion, compact fuel storage, and vehicle dry-weight reductions.

2025 System Characteristics

The 2025 spacelift system is derived through incremental application of technology and operational enhancements. This system description analyzes the progress toward 2025 based on the characteristics outlined in tables 1 and 2. Table 1 compares the attributes of a notional X-33 demonstrator and first through third generation MTVs against today's systems. Table 2 compares the attributes of notional first through third generation OTVs.

Table 1 MTV Systems Attributes

Current Systems


1st Generation MTV

2 Generation MTV

3 Generation MTV







Isp (seconds)




450 - 800









not applicable

2/3 MTV

X-33 + 20%



Weight (lbs)

150,000- 250,000





Capability (lbs to LEO)

up to 50,000

Suborbital Mach 15 (can pop-up small payloads)

<10,000 (up to 28,000 with pop-up & refly)

20,000 SSTO

up to 30,000 SSTO

Response Time


Days (Demo Hrs)

Hrs to a Day



Table 2 OTV Systems Attributes

1st Generation OTV 2 Generation OTV 3 Generation OTV
Isp High High High
Thrust Low Medium High
Reusable Yes Yes Yes
Weight (lbs) 30,000 - 40,000 30,000-40,000 <30,000
Response Time weeks hours hours
Propulsion Solar-ion Nuclear-ion Fusion or Antimatter
Primary User Commercial Military All

Primary Systems

The primary spacelift systems are divided into medium/light lift and heavy lift. The third generation MTV supplies 100 percent of all medium/light lift missions up to 30,000 pounds in the ETE and the ETO environments. The small market of heavy lift is accomplished by EELV, but the second generation commercial MTV and emerging third generation systems are rapidly consuming the market. As MTV proves its economic viability, more large payloads downsize. In the US, the advanced MTV spacelift wing strengthens air-and space-core competencies through a standardized modular command structure, modular and interchangeable payloads and weapons bays, technician-level maintenance, and on-demand responsiveness. In the STS environments, the OTV operates in conjunction with the international space station and/or the cislunar space defense station. Commercial OTVs perform satellite placement from LEO, satellite and station repair, research, and space debris removal. The DOD maintains a squadron of armed military OTVs for counterspace, force application, deterrence, and space-denial missions. Additionally, the military OTVs perform routine satellite maintenance, defense satellite positioning, and satellite repair on the national space architecture. They are attached to the space station defense directorate, which also performs the international space traffic control mission.

Multipurpose Transatmospheric Vehicles

The 2025 emerging third generation MTV is a high Isp (greater than 1,000 seconds), medium-lift vehicle that integrates composite materials, advanced computer diagnostics, fiber-optic and superconductor technology for compact energy generation systems. It also integrates a modularized infrastructure for maximum responsiveness and flexibility. The propulsion system is an "accelerator class" engine combining laser pulse detonation (LPD) and magnetohydrodynamics (MHD) fan-jet principles, as outlined in the appendix. The emerging fusion and antimatter technologies hold promise for a strategic application of the MTV with unlimited range enabling Space Command (CINCSPACE) to finally possess a planetary area of responsibility (AOR). The following data describes the vehicle design advances required through first generation and second generation vehicles.

First Generation MTVs

The X-33 program generated the first reusable demonstrator, which proved the potential for routine operations. The first generation follow-on military MTV is 20 percent larger than the X-33 demonstrator. The MTV space system retains 20 percent propulsion capability margin to enhance operational reliability. The MTV, a vertically launched, single stage ETO and ETE system, capitalizes on current technologies. The vehicle uses cryogenic fuels in the X-33-developed integrated powerhead rocket engine (see appendix) to achieve orbit. For lift missions greater than 10,000 pounds, the MTV uses the X-33 demonstrated satellite "pop-up" and refly capabilities. In the pop-up mode, the payload is deployed in the upper atmosphere and uses an expendable upperstage to place it in LEO. For the refly mode, MTV deploys small reusable aerodynamic platforms for both ETE and ETO missions. These small winged vehicles are capable of making drastic orbital plane changes in the upper atmosphere by using aerodynamic forces on their wing surfaces. The MTV performs space superiority missions through tailored, standardized, modular mission payloads and satellite refly. Additionally, in the transatmospheric ETE mode, the MTV demonstrates force application and a rapid response ISR capability.

Structural Materials

The current advances in composite technologies and thermal protection systems (TPS) are incorporated into a structure that is 20 percent larger than the X-33 but only 10 percent heavier, which should allow significant operational cost reductions. The TPS uses advances in current carbon-carbon (C-C) and carbon-silicon (C-Si) systems and thermoplastic pultrusion technologies derived from enhanced computer modeling of structural fluid dynamic solutions.22 These thermoplastic pultrusion manufacturing techniques produce tougher mechanical properties with longer life cycles. Additionally, the process requires no chemical curing, so production rates increase lower lengthy production costs. Cryogenic fuel storage builds on current aluminum-lithium (Al-Li) technologies. Electrical components and computers take advantage of advances in

high-temperature superconductors and first generation AI, and the vehicle uses fiber-optics for all control systems. Superconductors are manufactured to operate at 250 degrees Kelvin (-23 degrees Celsius), which currently seem viable by 2002.23 This enables order of magnitude smaller control and pump motors using current refrigeration systems allowing either more payload or fuel to be carried. Third order of magnitude increases in computing power and advances in AI enabled the vehicle to incorporate a real-time, self-diagnostic system with automatic self-repair and reroute capability.24 The system contains an interactive interface for technician fault isolation, rapid identification, and component replacement and enables a much smaller operational launch team.

Modular System Packaging

The MTV can be a manned or unmanned vehicle, depending on the mission. The vehicle in the manned mode uses a two-person crew: a pilot and a mission specialist, which can be a counterspace specialist, weapons officer, logistics specialist, or a

satellite-deployment specialist. The integration of fiber-optics, superconductors, and advances in space life support science produces a smaller modular crew life support system, which is removed to increase payload size in the unmanned mode. Virtual piloting is conducted from a modular command center and is accomplished by way of integrated satellite link using current computer technology advances and the improved global navigation capability. Payloads are encapsulated for both ETO missions and ETE. Modular payload and weapons deployment is successfully tested by the X-33 demonstrator.25 Human life support for special operations forces (SOF) deployable modules are in the test phase for the second generation vehicle.

Operational Infrastructure

The US Spacelift Wing uses an organization analogous to the 1995 Air Force wing structure plus a commercial technical assistance division. The military MTV takes advantage of commercially driven material technologies with investments in propulsion advances to deploy space-based weapons, lasers, counterspace technologies, and logistics. The spacelift wing is located in two main operating aerospace bases, but the command structure is modularized for rapid deployment to any US Air Force base. Figure 3-1 shows a conceptualized operational turn around for a potential MTV-type design. Relying heavily on vehicle self-contained diagnostics, a common facility is used for automated preflight and payload operations.26

Figure 3-1. Conceptualized operations for the MTV

Source: Lt Col Jess Sponable, Advanced Spacelift Technology (U), Phillips Laboratory, PL/VT-X, briefing, Air University Library, 2025 Support area, 6 March 1996. (Secret) Figure is unclassified. (Secret) Figure is unclassified.

Figure 3-1. Conceptualized operations for the MTV

Preventive maintenance and preflight are standardized procedures for technicians employing a "blue-suit" concept. The civilian technical assistance group handles major technical problems. Components are line replacement units (LRU) with separate two-level maintenance system outside of the preflight facility. Average turnaround time is less than six hours, including refueling, but a priority aerospace mission sortie turn around of less than three hours is possible. Prior to launch approval, on-pad alert MTVs perform a 15 minute diagnostic check, yielding a global response time of less than one hour.

Figure 3-2. Artist's Rendering of 1st Generation Spacelift Wing
Source: Dr Dick Mueller, Washington Strategic Analysis Team, "Global Response Aerospace Sortie," briefing, 6 March 1996.

Figure 3-2. Artist's Rendering of 1st Generation Spacelift Wing

The base additionally contains hydrogen/oxygen generation and storage facilities. The command structure consists of a communications building, which performs administration and is tele-linked to the space traffic control center in the space station's defense directorate, and the virtual command center, which holds the pilot control system and mission briefing areas (secure video-teleconference capable). Figure 3-2 is a conceptualized picture of an operating spacelift wing employing one possible vehicle configuration.

Second Generation MTVs

The second generation MTV integrates revolutionary propulsion into an improved first generation MTV aerospace frame. Dry-vehicle weight is reduced another 5 percent. The propulsion system is a first generation laser pulse detonation and magnetohydrodynamic "accelerator class" engine with laser air spike technology (see appendix). This propulsion system is designed to operate each engine variant in its most efficient mach regime. To increase engine thrust efficiency in the laser detonation cycle, the cyrogenic propulsion system uses a boron additive.27 The increase in Isp to greater than 600 seconds has rendered the satellite pop-up maneuver obsolete, since most payloads can be directly inserted into orbit. Propulsion margin of 20 percent is easily maintained. A commercial heavy lift MTV demonstrator is being tested, and a commercial passenger MTV is on the drawing board. The second generation MTV is the joint bomber/logistics transport capable of contributing to air-and space-core competencies. Advances in artificial intelligence and superconductors are incorporated into a fully self-contained preflight and diagnostic system with real-time self-repair and reroute. Additionally, these advances have reduced required personnel for refueling and maintenance support.

Structural Advances

Thermoplastic protrusion technologies are commercially adopted, and thermosets are past history. Research at Sandia National laboratories has developed powder metallurgy with high-gas atomization, which is now in production.28 The MTV is an all-composite design with Al-Li cryogenic storage tanks. Composites continue advances in C-C and C-Si with titanium derived alloys to lower structure weights 20 percent below baseline.29 These manufacturing technologies are commercially derived and provide an economical space frame with 20 percent lighter materials, long life cycle, and high strength, to further reducing life cycle costs. Additionally, the structure is supported by a commercial as opposed to military industrial base. This arrangement should spread spare and replacement costs across a larger group. It also should provide larger basing opportunities. To reduce control system weight, the system employs buckytubes (molecular-level electrical materials with AI) which are the electrical information carriers for the self-diagnostic system.30 They also manipulate micromechanical devices in the MTV's control systems.31 The MTV's surface is monitored by first generation shape memory alloys, which use piezoelectric actuators and fiber-optic sensors to transmit MTV control surface information to the real-time diagnostics that allowed personnel reductions.32 Superconducting quantum interference devices (SQUIDS) detect and measure the earth's magnetic field and are integrated into the MHD (an engine which uses the earth's magnetic field to generate energy) control portion of the "accelerator class" engine.33 A zero-degree Celsius superconductor has revolutionized the pump and motor industry, leading to a four-fold reduction in weight and size and again improving payload or fuel capability. These realistic electrical advances reduce heat dissipation requirements, lower both structural and volumetric weight requirements, and enable the development of real-time diagnostics and control systems, which improve reliability and operability.

Modular Payloads

The improvements in propulsion negate the pop-up requirement for satellite movement to LEO, but modular payloads remain important. The SOF deployment system is tested successfully and scheduled for production. Space special operations forces are being trained for future transatmospheric insertion. The MTV has assumed all strategic bombing missions.


Continued advances in materials, computing, and propulsion, lengthen mean time between overhauls. Commercial advances continue to be exploited by the military, and the volume of spacelift guarantees a robust industrial base. The self-diagnostic capability has reduced technician support. Pilot specialization is not required, because the same crew performs all missions. Turnaround time is less than three hours, with a potential to drop to 90 minutes for a priority sortie. Real-time diagnostics enable five minute alert status on the pad. Deployment of the US Spacelift Wing to anywhere in the US is less than 24 hours for a limited time depending on mission and orbital access required.

Orbital Transfer Vehicles

The emerging third generation military OTV is powered by a revolutionary engine supplemented by emergency high-density hydrogen fuel cells. While this system is in the demonstration mode, OTV requirements are met with first and second generation OTVs. The OTV squadron is supported by the international space station defense directorate, which incorporates the space traffic control system, or is part of either a cislunar or a orbital space defense station. The OTV carries out the routine operational missions of satellite deployment, repair, refueling, rearming, and reconnaissance. Further, the OTV is armed for counterspace, space denial, and space force application missions. The advantages of this system are economical space architecture maintenance, rapid response positioning of assets and global reach missions for space superiority. The vehicle is a single piloted vehicle (F-16 sized), unmanned and controlled virtually in the defense directorate control center. Structure advances and diagnostic computer advances are identical to the MTV systems. The following are the advances required from first through second generation vehicles.

First Generation OTV

The OTV system capitalizes on the satellite capture demonstrations from the shuttle program. Research into magnetic satellite capture is on-going. The OTV is considered an integral part of the IPDS. The propulsion system is solar-electric ion drive; the low thrust is supplemented by emergency fuel cells during national contingencies. For ion drive, solar energy is used to ionize an inert gas and extract it through a nozzle to produce thrust (see appendix). The infrastructure is attached to the defense directorate and, in national emergencies, is operationally chopped to the US Spacelift Wing. The OTV demonstrates the first space laser satellite destruction. Composite technologies and unknown orbital trajectories make the vehicle stealthy. Maintenance of the OTVs is accomplished by modular repair coupled with MTV similar built-in diagnostics, automatic preflight, and technician-level maintenance. The first generation OTVs are attached to the international space station infrastructure or capitalize on a dedicated cislunar or orbital defense space station, and financial investment recapitalization occurs within seven years (similar to emerging industries). Overhauls of the OTVs are conducted on Earth every two years.

Second Generation OTV

Nuclear-electric ion drive propulsion is incorporated with higher thrust. The nuclear energy generates a higher degree of ionization generating more thrust and range. These attributes enable the military OTV to meet the mission flexibility and responsiveness requirements. Satellite capture using magnetic fields is a demonstrated capability. The spacelift infrastructure has expanded to include OTV overhaul in space. Structure composites and computer advances are identical to MTV development. Communication advances enable OTVs to be permanently part of the US Spacelift Wing with the defense directorate as the on-scene headquarters. The MTV missions and the OTV missions enable space superiority and global force application. Fusion and anti-matter propulsion technologies hold promise for the third generation OTV in a strategic role. CINCSPACE finally possesses a planetary AOR defined by the earth-moon system, which is a sphere inscribed by the moon's orbit.


The stealth characteristics of the MTV are its high speed (>Mach 25), large portion of composite structure, and unpredictable orbital position. Counterspace devices on satellites, ground-based laser devices, and direct attack on launch facilities are the greatest threats. The long range of weapons deployment and rapid sortie ability cause unpredictability and standoff capability. Rapid deployment of the launch infrastructure prevents effective strategic targeting. The OTV is stealthy by nature, but it is susceptible to international sabotage at the space station and counterspace satellite defense weapons. The OTV's orbital unpredictability and speed are its greatest assets. Internal defense on the station is a requirement. More powerful lasers, kinetic weapons, and particle beams give extended standoff for force application roles. The OTV also is capable of nonlethal satellite blinding and deception.

Table 3 Qualitative System Comparison

System Attribute Refuelable Blackhorse Single Stage MTV 2-Stage with Mothership Magnetic Rail launched TAV EELV
Capability (lbs to orbit) Good-Excellent Good-Excellent Good-Excellent Good-Excellent Excellent
Reusable Yes Yes Yes Yes No
Responsiveness Good Excellent Good Good Fair
Flexibility Good Excellent Good Fair Fair
Soft abort Good Good Good Good None
Logistics Good Excellent Good Good Fair
Operational Simplicity Good Excellent Good Good Fair
Cost ($/lb to LEO) Good Excellent Good Good Fair
Develop-ment Risk High Medium Medium Medium-High Low

The MTV/OTV system performs two basic space deployment tasks: lifting payloads to orbit and transferring payloads between orbits. The utility of systems performing these functions is measured in terms of weight to orbit, volume to orbit, civilian surge capability, system responsiveness, and reusability for MTVs. OTV utility is measured in terms of timeliness and reusability. In addition to the spacelift tasks, the MTV is used for airlift, strike, and ISR tasks. The MTV reaches anywhere on the globe in less than an hour, so it can perform vital missions rapidly. For example, airlift systems are employed to move a brigade of troops to a theater, but MTV can provide rapid SOF insertion for squad-sized units. These Air Force Institute of Technology derived utility measures are used to determine which weapons systems in the Air Force 2025 study hold the most promise. The following is a more detailed qualitative comparison using required system attributes.

The MTV/OTV system was selected from a variety of systems that addressed the spacelift mission (table 3). Each of these systems provided enough capability to meet the bulk of mission requirements, but the EELV was chosen initially by other studies, because it was the only system with low-development risk and because it captured the entire current mission model. While EELV provided a needed initial cost reduction, it was the only expendable system; so, it did not offer the promise of routine operations. A reusable system was destined to take center stage. Two stage systems and the single stage MTV had medium risk while the magnetic rail and oxidizer refueling systems presented some unique new technical challenges. A magnetic rail similar to the EELV was tied to extensive infrastructure, which reduced its flexibility as a multipurpose system. The major discriminator between MTV, blackhorse, and two stage to orbit vehicle was operational simplicity. The blackhorse concept required added development and maintenance of a tanker capable of refueling oxidizer at high speed in addition to the basic vehicle. This additional infrastructure increased logistics requirements, reduced flexibility of deploying the system, and complicated responsiveness. Similar concerns existed with the mothership in the two stage to orbit concept. This state left the MTV as the best choice to provide simple routine operations capable of satisfying all existing and potential customers.

The first generation MTV system acquisition cost was $1.7 billion, and the prototype vehicles were scheduled for fielding in 2003. The first functional vehicle was declared operational for 2010. With routine operations already proven, second generation costs were held to under $1 billion, and the system was declared operational in 2020. Third generation systems are still in development.

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Contact: Air Force 2025
Last updated: 11 December 1996

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