Chapter 2
Required Capabilities

The cost of spacecraft has come down an order of magnitude in dollars per band width during the last decade. The cost of launch is $10,000 a lb. We want $1,000 a lb.

-NASA Administrator Daniel S. Goldin

The 2025 spacelift system is a dedicated, responsive, reliable, and affordable operation that supports DOD space superiority missions. The Air Force Executive Guidance, December 1995 update, describes space superiority as a "core competency" for the future.6 The 2025 spacelift system employs a combined concept of lift from earth-to-orbit (ETO), earth-to-earth (ETE), and space-to-space (STS) to support movement of US assets. The ETO spacelift is the routine operation of sending payloads into LEO. The ETE spacelift focuses on transferring cargo globally through space and executing global-presence missions using space as a transit medium. Finally, the STS spacelift is transferring, positioning, or maintaining payloads in orbits using a reusable orbital vehicle to operate within the space environment.

Commercial industry has driven the responsiveness of spacelift toward routine operations in 2025. Advances in computing, composite materials, and energy generation has lowered payload weight for most routine satellite requirements, spurring the proliferation of medium and light lift systems. With launch schedules measured in minutes instead of months, the commercial markets are dominated by the most capable systems and the most responsive providers. Deep space exploration, lunar economic expeditions, and space station support still require a small percentage of heavy lift capability, but this operation is performed by a combined corporate and government venture.

In 2025 power is defined by information. Information dominance is maintained through a combination of ground, air, and space sensors that feed an extensive data-fusion system. Responsive spacelift supports this system. With events transmitted at the speed of light, the response time to a global crisis is minutes. Spacelift system responsiveness is assured by assets already positioned in space and by ground-based space assets, which can be launched rapidly from several locations. The 2025 space forces are the global presence deterrent with rapid response launch capability to support a myriad of space missions, which includes space control, force application, space maintenance, counter space, command, control, communications, computers, and intelligence (C4I), and research. These assets include planetary defense and intersolar system travel. In the ETE mode, any global point must be accessible from CONUS base in less than an hour.

The 2025 spacelift system is characterized by reusability, high-thrust/energy propulsion, modular mission packaging, economically designed mass fraction, streamlined infrastructure, and operational simplicity. The above solution characteristics, coupled with routine sortie operations, drive the affordability of placing a payload into orbit. With the resulting lower cost per pound to orbit, market demands for exploiting the medium increase. This in turn drives costs even lower. Once the system demonstrates affordable spacelift, innovative ETE missions are pursued. The following are expansions of the above solution characteristics, starting with some definitions.


Specific Impulse (ISP): the standard measure of propulsion efficiency. Simply defined, Isp is the number of seconds a pound of propellant produces a pound of thrust7. ISP is a measure of fuel efficiency for comparing propulsion systems, similar to octane measurements for automotive gasoline.

Mass Fraction: In this paper, mass fraction refers to that portion of the vehicle weight that is propellant (propellant mass fraction).

Cryogenics: Liquid hydrogen and liquid oxygen propulsion systems common to many current spacelift systems, including the space shuttle and the Centaur upper stage. Cryogenic propellants must be kept cold to remain in a liquid state. This complicates the storage and operations. However, cryogenics are much more environmentally friendly than other current chemical propellant alternatives.

Generations: A method used in this paper to identifying broadly system characteristics that relate to capabilities instead of time. The three generations of spacelift in this paper are:

Margin: the portion of systems performance that remains unused and is kept in reserve to ensure reliability. Current spacelift systems leave little margin. Propulsion systems are pushed to their maximum. This is analogous to driving a car at maximum revolutions per minute all the time. With the high cost of expendable spacelift, users want to use the largest possible payload, so only minimum safety margin is maintained. By running the propulsion system below its maximum and thus maintaining margin, maintenance is reduced, reliability is increased, and costs are decreased.


Reusability in 2025 refers to routine aircraft-like operations. The system does not require standing armies of engineers to check and double check each system prior to a launch. Instead, MTVs and OTVs are flown and reflown with minimal maintenance between most missions.

The concept of a reusable vehicle is not new. The shuttle's original premise was complete reusability, but its ballooned infrastructure, zero-defect safety requirements, and R&D processing mentality prevented its use in the truly routine operational sense. One of the main tenets of the X-33 space plane is proving the operational reusability concept.8 The Space Launch Modernization Plan states that solving current technology limitations are critical. These limitations excessive reliability/failure demands, large infrastructure costs, and the lack of institutionalized launch program oriented towards standardized requirements, metrics, and goals.9 Further, the President's National Space Transportation Policy demonstrates the complementary nature of the reusability concept with military requirements. This includes vehicles maintained in "flight readiness-style," incorporated autonomous diagnostic design, flight vehicle support, ground support facilities, support logistics controlled by automatic interactive scheduling, and "airplane-like" operations. This pattern results in short turnaround with comparable safety requirements.10

Another advantage of reusability is increased responsiveness. The 2025 spacelift system is responsive in minutes with a fleet of MTVs continuously ready for launch missions. The MTV fleet is supported by a technician-based preventive maintenance system, with planned periodic overhauls for modernization. Advances in computer capabilities and artificial intelligence provide real-time and on-the-fly diagnostics and automated systems rerouting, while improvements in high temperature thermal conductors and fiber-optics integration reduce power requirements. Innovative thermal and radiation protection extend product life cycles, allowing reusable systems to last longer. Light-weight structural components are improved for longevity and resistance to cyclic failure. Overall, required system redundancies are minimized and a soft-abort capability is integrated to allow a return to launch site (RTLS) capability. Each of these advances contributes to MTV responsiveness.

Reusability is essential for routine operations, but some expendable systems still launch in 2025. A small portion of heavy lift is accomplished by the evolved expendable launch vehicle (EELV), but emerging third generation propulsion holds promise for NASA and commercial reusable heavy lift capability. The remaining heavy payloads are adapting to the standardized MTV requirements to avoid the excessive cost and environmental concerns associated with expendables. Eventually, all spacelift will be accomplished using reusable vehicles, but MTV performance increases are required to capture the entire spectrum of missions.

High Specific Impulse Propulsion

To satisfy all MTV performance requirements in 2025, high ISP propulsion is a primary solution characteristic. The 2025 commercial industries dominate the conventional solid and cryogenic rocket launch market. These corporations and nonstate actors have developed reliable launch schedules with safety records similar to that of the airline industry, standardized chemical propulsion systems, decreased payload volumes and weights, and streamlined infrastructure costs. Foreign governments, unconstrained by environmental considerations and zero-defect requirements, use 1990s space technology for attracting commercial enterprises to satisfy their own national objectives. Though these systems optimize expendable technology, they cannot compete with a high Isp, reusable MTV.

In 1994 Lt Gen Jay W. Kelley, chairman of the SPACECAST 2020 study, tasked the faculty of the Air Force Institute of Technology (AFIT) to investigate unconventional approaches to solving national spacelift problems.11 One of the identified problems was the current limitations of Isp. Conventional chemical propulsion is reaching its maximum ISP of 450 seconds. This conventional chemical limit, analogous to the sound barrier, suffices in propelling payloads to LEO, but does not give the propulsion margin to enable true mission operability in space. Unconventional approaches are necessary to break through the chemical propulsion limits and meet the flexible operational requirements of 2025 spacelift.

Propulsion, coupled with structural mass fraction improvements, continue to drive technology in 2025. Presently, the cost of placing mass in orbit is $20,000 per kilogram (approximately $10,000 per pound), and this cost is proportional to the dry-vehicle weight of the lift vehicle to payload, the supporting structure, and the energy of the fuel.12 New World Vistas also advised research into the "computational design of energetic materials," lighter satellite payloads, and lighter lift vehicular materials coupled with lower mass-to-fuel ratios and compact computer diagnostic/control systems, which support the 2025 spacelift solution characteristics.13 Lower mass fraction and streamlined infrastructure are discussed later in this chapter.

High- ISP technology advances enable the 2025 spacelift system to consist of versatile, vertical launch and combined vertical or horizontal landing recovery operations. The 2025 MTV employs a second "transitioning to third" generation propulsion system, which generates both high ISP and high-thrust. High-efficiency ion drive systems (solar and nuclear electric powered) are primary maneuvering systems on satellites and OTVs. These systems maximize ISP without requiring the high-thrust needed to reach escape velocity in the ETO mission. The development of future unconventional fuels are a synergistic DOD, NASA, and commercial effort, which requires extensive sharing of information to spur the technology push required for reliable, high-energy, high-thrust propulsion.

Presently, the Space Launch Modernization Plan states that the current and projected funding is insufficient to support even a meaningful core space launch technology research program.14 To create a core technology research base for furthering only current spacelift concepts (projected to 2013), which includes existing cryogenic and solid fueled upgraded launch vehicles, evolved expendable launch vehicles, and evolved reusable launch vehicles, the study recommended funding be increased from the current $45 million to $120 million.15 The final plan lacks any revolutionary propulsion concepts and, therefore, does not provide the futuristic outlook needed for 2025. It recommends evolved expendable rocketry, increased cooperation with Russia for advanced engine technology and performance data, and pooling resources of the international community, rather than the strategic pursuit of unconventional propulsion alternatives. For achievement of routine spacelift operations, the US needs a strategic vision that drives propulsion technology towards unconventional solutions to achieve high ISP. Revolutionary and evolutionary propulsion advances, which have the potential to achieve a third generation "on-demand" propulsion system, are required to provide the full spectrum of MTV capabilities.

Modular Mission Packaging

Modular mission packaging is also not a new concept, but one derived from the X-33 concept of launching modularized payloads, which include satellite constellations, weapons deployment, logistics, and, even personnel.16 Using encapsulated payloads with standard vehicle interfaces, mission flexibility, and responsiveness are enhanced, and ground operations are streamlined. The payloads are deployed from the payload bay singularly or in an integrated package. Moreover, the payload package is delivered and stored hours, days, or months in advance. The pilot of the vehicle can fly virtually from the ground, or fly in the manned mode if required for strike, surveillance, or mobility missions. The manned mission package has less residual capability, since the modular crew compartment uses some of the volume and performance normally dedicated to payload.

Economical Mass Fraction

Coupled with the decreased mass fraction due to propulsion technology pushes 2025 spacelift takes advantage of continued advances in light weight composites. Figure 2-1, disregarding the space shuttle main engine (SSME) performance, demonstrates the improving relationship between the dry vehicle weight, mass fraction, and specific impulse as technology advances over time. The upper lines demonstrate that the heavier structure increases propulsion design risk (e.g., a 20 second ISP shortfall can double the vehicle dry weight requirements). Conversely, given the baseline shown in the graph, one sees the immediate benefit of even 20 percent lighter future structural composites. Even a large change in engine performance does not significantly add to the dry weight of the vehicle.

The applications of light weight composites to structural materials continue to be integrated into air-breathing systems as demonstrated by the B-2 and the MV-22 Tiltrotor aircraft projects.17 These advances also reduce the size and weight of many payloads. Most satellite systems, deployed in distributed constellations, display trends toward weights in the 10s to 100s of pounds, driving most lift into the medium and light categories.

Figure 2-1. Mass Fraction Reduction Baseline

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.

Figure 2-1. Mass Fraction Reduction Baseline

The 2025 spacelift uses ultralight composite materials, which include structural composites, high/low temperature resistant materials, and revolutionary manufacturing technologies (singular crystal structures, automatic winding, and thermopultrusion.

Light-weight electronic systems employ fiber-optic technologies with adaptive commercial electronics (such as guidance) and self-diagnostics with expert systems, automated self-repair and reroute, computer programming advances (autocoding, molecular storage), and artificial intelligence.18 Moreover, advances in high-temperature superconductors reduce friction requirements, produce more efficient power generation and engine systems, and reduce the component size of equipment. The above technologies help to reduce the MTV's dry weight, which, in turn, improves mass fraction.

This technology push utilizes and develops lightweight structural components with a long-design life and resistance to failure within reasonable engineering criteria. The combination of high Isp propulsion and light dry vehicle weight results in economical mass fraction. MTV's low-mass fraction and high-energy propulsion give it the performance needed to satisfy all customers.

Streamlined Infrastructure

The 2025 spacelift infrastructure consists of small, modular general purpose facilities and a minimal processing/operating team. The 1995 NASA report of shuttle ground operational efficiencies noted that "the life cycle cost triangle of flight hardware, processing facilities/GSE, and headcount must be dramatically and radically reduced" to pursue an affordable operational tempo.19 Additionally, the direct failure and opportunity costs experienced by the current space program must be eliminated.

Figure 2-2. Reusable MTV Maintenance Requirements

Source: Phillips Laboratory, Advanced Spacelift Technology (U), 1996. Provided current airframe maintenance data only. (Secret) Figure is unclassified.

Figure 2-2. Reusable MTV Maintenance Requirements

The 2025 spacelift is a streamlined organization using the technician-level maintenance structure coupled with civilian technical advisors. The armies of technicians employed to launch rockets in the 1990s are no more. Figure 2-2 proposes first generation MTV maintenance requirements. Using the above solution characteristics, the 2025 Spacelift system pushes spacelift maintenance requirements toward today's fighter maintenance levels. Reliability is ensured through standardized operation programs augmented by real-time, continuous diagnostics and artificial intelligence (AI) driven self-repair and rerouting. Standowns due to failures are limited locally to specific MTV squadrons and do not necessarily ground the entire spacelift system. While investigations are conducted, operations are not normally impeded.

The 2025 spacelift system combines easy maintenance and engine access with interactive computer diagnostics and fault tracing. Ground operations use common equipment and modular component replacement with post-repair-two-level maintenance (2M) capability. Modular command and operations centers, coupled with vertical launch characteristics, enable a smaller physical infrastructure and basing requirements. Virtual pilot control operations lead to larger cargo payload deliveries without human life support concerns. Modular payloads generate generic loading operations and real-time mission flexibility. The composite nature of the missions reduces pilot specialization requirements. To mitigate the risk of an enemy targeting MTVs, the modular organizational concept provides mobility for flexible orbital access from numerous launch facilities.

Current launch operations in the 1990s are concentrated at Cape Canaveral Air Force Station, Florida and Vandenberg Air Force Base (AFB), California. In 2025 physical spacelift infrastructure is more dispersed to include operations at higher altitude locations, closer to the equator for greater orbital access and more remote for increased public safety. Primary MTV locations include Peterson AFB Colorado, and Holloman AFB New Mexico. Clear launch pads, free of massive towers and other support facilities, provide simple ground operations and easy access maintenance. Encapsulated cargo reduces payload processing facility requirements. The resulting infrastructure is less expensive to maintain and facilitates routine operations.20

Operational Simplicity

The 2025 spacelift system exploits advances in reusability, propulsion, and materials to meet spacelift, ISR, strategic strike, and mobility requirements with a single platform. Complex operational solutions to such reusable vehicle performance as a mothership, refuelable craft, or magnetic rail accelerated vehicle proved too costly. Each of these operational solutions work around to the propulsion challenge required extensive additional infrastructure and industrial base support. The Black Horse refuelable spacecraft concept was touted in the Spacecast 2020 study.21 With the added development, operations, and support costs of a mothership, an oxidizer transferring airframe, or a complex, inflexible rail launch site, these novel approaches to increasing performance could not compete with the low life-cycle cost of a SSTO MTV concept.


By employing the combination of these solution characteristics in an operational environment, spacelift becomes affordable. Figure 2-3 demonstrates the commercial flight-rate potential as MTV launches become operational and cost per pound is driven toward $200/lb. Further, history shows that the introduction of new operational transportation systems opens new markets, which, in 2025, include space exploration, space economic resource exploitation, hazardous waste disposal, rapid response commerce, and space settlement. For the military, the 2025 spacelift system results in rapid response supporting core competencies at an operationally affordable cost. The initial driver of cost reduction is reusability. Other drivers include decreased personnel overhead and improved reliability. The remaining solution characteristics described above contribute to further cost reductions.

Life-cycle costs for an MTV wing is comparable to current bomb wing requirements adjusting for inflation, but the utility of the vehicle makes it more affordable than maintaining separate mission platforms. AS figure 2-4 illustrates, the combination of the solution characteristics (assuming nominal operating costs) and operational sortie rate (150-200 sorties/year) has the real potential to achieve $200 per pound payload cost for a third generation MTV.

Figure 2-3. Commercial Launch Potential

Source: National Aeronautics and Space Administration, Space Propulsion Plan (Draft),
Marshall Space Flight Center, 22 January 1996, 8.

Figure 2-3. Commercial Launch Potential

Figure 2-4. Impact of Flight Rate on per Flight Cost of an 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.

Figure 2-4. Impact of Flight Rate on per Flight Cost of an MTV

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Contact: Air Force 2025
Last updated: 11 December 1996

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