Prepared Statement by Robert Hickman at a Senate Hearing on Space Shuttle and the Future of Space Launch Vehicles

The Testimony of Mr. Robert Hickman Director of the Advanced Spacelift and Force Application Directorate, The Aerospace Corporation

Mr. Chairman, distinguished committee members and staff:

I am pleased to have the opportunity to describe the studies conducted by The Aerospace Corporation as they relate to advanced launch system design. The Aerospace Corporation is a private, nonprofit corporation, headquartered in El Segundo, California. As its primary activity, Aerospace operates a Federally Funded Research and Development Center (FFRDC) sponsored by the Under Secretary of the Air Force, and managed by the Space and Missile Systems Center (SMC) in El Segundo, California. Our principal tasks are systems planning, systems engineering, integration, flight readiness verification, operations support and anomaly resolution for the DoD, Air Force, and National Security Space systems.

For the past forty-four years Aerospace has helped the Air Force plan and develop launch systems. Recent studies performed by Aerospace have focused on advanced launch system concepts that could support the Defense Department, NASA, and the commercial sector. This includes involvement in joint studies where Aerospace worked closely with NASA and the Air Force to address launch system issues from a national perspective. The Advanced Space Lift Study began in 2002 and was the prelude to the Operationally Responsive Spacelift (ORS) Analysis of Alternatives (AoA). Aerospace performed the technical analysis for the ORS AoA that is intended to identify the acquisition strategy for future Department of Defense launch systems.

Desired System Capabilities Today’s launch fleet routinely deploys sophisticated spacecraft for navigation, communication, meteorology, intelligence, surveillance, reconnaissance, and space exploration.

Though impressive, today’s launch fleet is not without limitations. Launch costs and preparation times limit space applications to a handful of high-value services. A revolution in new space applications is possible, but would require a new generation of launch systems to reduce cost and preparation times. The Department of Defense and NASA have expressed interest in such “transformational” capability; but before pursuing such a system, three major interrelated questions must be answered.

First, what capabilities are envisioned for the system? The goals of the defense, civil, and commercial space sectors are different, and the degree to which common solutions can be developed will determine whether separate or joint programs are pursued. Second, what sort of system should be designed? The choice between an expendable and reusable system, for example, will depend on whether design techniques and manufacturing technologies can be improved enough to make reusable systems operable and affordable. Third, what development strategy should be employed? The combination of risk tolerance, available budget, and timeframe of need will dictate whether developers seek radical advancements through aggressive technology projects or accept a safer, more incremental approach. Defense Perspective Defense launch systems are in the midst of a major transition. The heritage launch systems that served the nation’s needs for decades are now being retired and replaced by a new generation of launch vehicle families under the Air Force Evolved Expendable Launch Vehicle (EELV) program.

These vehicles are adequate to support the current mission manifest of national security satellites; however, the Air Force has identified a need to launch tactical space missions that support war fighters in real time. These missions would allow global strike capability, rapid augmentation of satellite constellations, rapid replacement of compromised space assets, deployment of specialized space vehicles for combat support, and wartime protection of American space assets. The Air Force is clearly considering that future military engagements may require the launch of large numbers of payloads in just a few days. The majority of these payloads are anticipated to be less than 10,000 lbs. Prosecuting a war in this manner would be impossible without launch responsiveness. Through the Operationally Responsive Spacelift (ORS) Assessment of Alternatives, Aerospace is assisting the Air Force Space Command define its future launch system plans. At this point, the AoA is nearing completion. Civil Perspective In the course of more than 20 years, the space shuttle has launched more than 2 million pounds of cargo and sent more than 300 people into space. After the start of operations, however, it became increasingly clear that the shuttle was difficult to operate, maintain, and upgrade. Also, the differing orbiter configurations made each flight preparation a painstaking ordeal.

The space shuttle Columbia flew its 28th and final mission, launching on January 16, 2003, and breaking up 16 days later on its return to Earth. A new plan announced in early 2004 calls for a return to shuttle flights (until the International Space Station is completed) and development of a space vehicle capable of carrying a crew to the moon and beyond. Although no specific launch vehicle requirements have yet been defined, it is anticipated that a large launch vehicle will be needed with a lift capacity greater than 100,000 lb and with a relatively low launch rate. Commercial Perspective The traditional commercial launch market is focused principally on lofting communications spacecraft into Earth orbit. A methodology developed at Aerospace to explore launch costs suggests that the low flight rate required to support traditional communications spacecraft is not large enough, by itself, to justify large economic investments needed to achieve dramatically lower launch costs. To regain their competitive advantage, the U.S. commercial sector needs significantly lower launch cost for 10,000 to 40,000 lb. payloads. Expendable Vehicles Expendable launch vehicles could support responsive tactical space needs, just as ICBMs do, but the cost would be prohibitive. Current launch costs range from $5,000 to $10,000 per lb. of payload to low Earth orbit. The significant efforts of the EELV program have achieved moderate cost reductions, particularly for the heavy-lift vehicles, which use the same production line as the medium-lift versions. This commonality effectively provides the heavy-lift rocket with production rate advantages over the Titan IV and also permits the costs of engineering and logistics to be spread over a larger number of vehicles.

EELV has invested heavily in the latest manufacturing techniques and processes. Still, further significant decreases in medium or heavy lift expendable launch vehicle cost are not anticipated. On the other hand, small launch vehicles currently cost substantially more per pound of payload than their larger counterparts. The FALCOM program is a joint effort between the Air Force and DARPA to determine if a significant reduction in the cost of small expendable launch vehicles can be achieved. Reusable Vehicles Reusable launch vehicles are commonly proposed as responsive and inexpensive alternatives to expendable rockets. Analogies to aircraft systems suggest that reusing flight hardware should substantially reduce cost. However, in the case of the Space Shuttle this was not the case.

Understanding the achievable operability of future reusable launch vehicles is crucial in determining their viability. Aerospace developed the Operability Design Model specifically to evaluate maintenance, turnaround operations, and recurring cost as a function of launch system design. Using this tool, Aerospace evaluated the design features that control operability and determined that a new vehicle could improve operations by one to two orders of magnitude compared with the space shuttle simply by incorporating:

• Reduced vehicle complexity to reduce the number and type of components that must be serviced
• Increased design margins to provide a robust vehicle design with improved component life
• Improved accessibility and Line Replaceable Units (LRUs) to facilitate maintenance
• Modern thermal protection systems with 100 times the durability of Shuttle tiles
• Integrated Vehicle Health Monitoring to automate vehicle checkout
• Modern propulsions system designs with 10 times longer system life
• Non-toxic propellants that don’t require hazardous processing
• Standardized practices and procedures for vehicle repair

Even with the industry’s best operability analysis tools, experts agree that such estimates carry significant uncertainty. Credible estimates of turnaround time for the next reusable launch vehicle range from 2 to 10 days. This uncertainty is a problem for the Air Force because it will affect how many vehicles and facilities are needed to accommodate a surge in demand (for example, during wartime). This affects cost sufficiently that the difference between a 2-day and 10-day turnaround may determine the ultimate choice between expendable or reusable launch vehicles.

Estimates of reusable launch vehicle production cost are also uncertain because the only actual data point is the space shuttle. The per-pound cost to build each orbiter was twice that of the Air Force’s most expensive aircraft, the B-2 bomber. Were this to hold true for the next reusable launch vehicle, production costs would severely limit its affordability. There are, however, rational arguments suggesting the cost will be lower. For example, the shuttle was the first of its kind, and was never optimized to control production cost. The orbiters have life-support systems, and must be built to safeguard the lives of the crew. The shuttle features distributed, rather than modular, subsystems. The shuttle program did not have access to the latest materials and production technologies. All of these problems can be corrected or minimized by using modern designs, technologies, and production techniques. Nonetheless, a factor-of-two uncertainty in production cost greatly affects the decision on expendable versus reusable launch vehicles. According to Aerospace analyses, reusable launch vehicles that have been optimized for minimum dry mass have staging velocities (that is, the velocity at which the second stage deploys) roughly between Mach 10.5 and 11.5. In this case, the orbiter will be about half the dry mass of the booster. The mass of the reusable launch vehicle will grow steadily as the staging velocity deviates from this range. For example, if the staging velocity grows higher, the booster must be bigger to generate more thrust; if the staging velocity is lower, the upper stage will have to make up the difference to reach orbit. This is the problem faced by single-stage reusable launch vehicles. Single-stage vehicles are not practical without significant advancements in materials and propulsion technologies; however, two-stage vehicles are undeniably feasible, given the state of existing technologies. Air-Breathing Reusable Vehicles The appeal of air-breathing vehicles is that they get their oxidizer from the atmosphere, rather than carry it with them. Thus, they might, at least in theory, be smaller and less expensive than conventional rockets. The X-43A/C demonstrator programs represent crucial steps toward achieving an operational hypersonic capability. The recent successful proof-of-concept X-43A flight demonstration is an important and welcomed milestone. These demonstrations should provide a more credible foundation for predicting hypersonic vehicle performance, building upon, and hopefully, validating available CFD analyses and prior short duration wind tunnel tests. Many challenges remain before an operational capability can be achieved, particularly in the following areas of system operability over the complete mission flight regime:

• Propulsion
• Structures and materials
• Airframe aerodynamics and controls
• Thermal management

The Aerospace Corporation concurs with the space access development roadmap established by the NASA/Air Force Partnership Council in its assessment of hypersonic vehicles. A series of demonstrators increasing in scale and operational realism will allow for maturation of hypersonic technologies to an operational status. This development effort was estimated at about $24 billion (excluding the rocket-oriented efforts), requiring at least 15 years to complete. In this regard, we feel that hypersonic vehicles offer potential as a far-term solution but should be considered high risk. Hybrid Vehicles A hybrid vehicle consisting of a combination of a reusable booster with expendable upper provides a lower risk alternative to achieve responsive and affordable space lift. It could potentially reduce current launch costs by a factor of three and achieve a routine turnaround time of 2 to 4 days. Assuming optimal staging, at about Mach 7, the hybrid vehicle would only expend about one third as much hardware as a comparable expendable rocket. Thus, their recurring production costs are much lower. Also, the mass of the reusable booster stage for a hybrid is about 45 percent that of a fully reusable launch vehicle. Consequently, development and production costs are significantly less. For these reasons, even relatively low launch rates could economically justify their development.

The hybrid vehicle also carries less risk than a fully reusable launch vehicle primarily because it does not employ a reusable orbiter. Reusable orbiters present a difficult technical challenge, as they must survive on-orbit operations and reentry through Earth’s atmosphere without significant damage. The reusable booster experiences a much less severe environment, resulting in fewer technical challenges and less risk.

Figure 1 depicts the estimated manpower to process a hybrid compared with the Space Shuttle and the rationale to achieve a 26-hour turnaround time. Figure 1. Comparison of Processing Manpower For Space Shuttle and Hybrid Vehicles

Designed with higher margins and vehicle health monitoring, the next generation of rocket engines is anticipated to have an operational life of 100 flights with a turn-time of 1-2 shifts. Electro-mechanical actuators and self-contained hydraulics can eliminate most of the time-consuming activities required to process the Shuttle hydraulic system. Batteries can replace complex fuel cells and auxiliary power units. The thermal environment for the hybrid’s reusable booster would require minimal thermal protection systems. The booster would also have a limited need for reaction control systems that could be provided by gaseous reactants. Cannisterized payloads eliminate the need for payload bay reconfiguration between flights. The hybrid vehicle itself would not contain crew systems. Numerous other enhancements have been identified that give a hybrid vehicle a short 26-hour timeline. Many of these enhancement apply to both hybrids and full reusable systems, but due to the added complexity and the stressing thermal environment of an orbiter, reusables have longer processing timelines and with higher uncertainty and risk. Development Strategy While many development strategies have been considered over the years, the Air Force favors an evolutionary approach, focusing on incremental enhancements in capability. Flight tests of a demonstration vehicle are critical—to reduce uncertainties regarding achievable production cost and responsiveness, to supply information needed to crystallize a decision on an objective system, and to provide an affordable flight test bed to demonstrate design features and technologies needed to achieve various future technical objectives.

The hybrid is considered a relatively low-risk first step toward an operationally responsive spacelift capability, one with clear advantages over expendable and reusable launch vehicles. The performance of this hybrid will have far-reaching implications. If the cost and responsiveness of the reusable booster turn out to be on the low end of predictions, then the Air Force and NASA might decide to pursue a fully reusable launch vehicle as the next step. If not, then the hybrid configuration would still provide a cost effective solution.

Clearly, no first step in an evolutionary process can satisfy all the objectives of defense, civil, and commercial sectors. But the evolutionary approach establishes a low-risk process for building upon successes, ultimately supporting most or all spacelift needs. As they mature, this approach allows new technologies to be incorporated into the system to enhance system capability at low technical risk.

Modular Launch System Design The initial cost of a new launch system for either DoD or NASA is relatively high. The combined cost of system development, facilities, and fleet procurement will reach well into the billions of dollars, even for small fleets. For this reason, it may be unaffordable to develop completely separate reusable launch vehicle designs for defense, commercial, and civil communities. By minimizing the number and type of stages that need to be developed, modular development approaches will probably be more affordable to pursue to support the needs of the DoD, civil and commercial community. For example, derivatives of boosters and orbiters could be used in various configurations to support a wide range of payload classes. While the derivatives would not be identical to the original vehicles, they would possess common systems and components, thus reducing development and production costs. This commonality would also reduce the operational costs of logistics and sustaining engineering, which are major recurring costs.

Figure 2 is an example of a notional spacelift architecture, designed by Aerospace to support a broad range of payloads, based on derivatives of only two vehicle elements. The first vehicle is a hybrid capable of launching 12,800 lbs to low earth orbit. Converting the hybrid’s reusable booster to an obiter that is combined with a new larger booster generates a 25,000 lb. lift capacity. Combining two of these boosters with a third orbiter derivate increases lift capacity to 87,000 lbs. Finally using two of the larger booster with an EELV common core booster produces a super heavy lift capacity of 160,000 lbs. Figure 2. Modular Family of Vehicles – Based on Variants of 2 Reusable Stages

In closing, the ORS AoA recommends the Air Force pursue an advanced launch vehicle development strategy that incorporates an evolutionary development approach. The FALCON small launch vehicle program is the first step in that process. A hybrid vehicle represents the next logical step in developing larger more affordable and responsive reusable solutions. It can potentially lower the cost of space transportation by a factor of three. If successful, subsequent steps that may be fully reusable could further reduce the cost of space transportation. Modular vehicle designs can be developed that support all national needs at a lower cost than developing separate systems. The reduced size of the engineering, logistics, and processing infrastructure combined with a higher vehicle flight rate will also minimize recurring cost. The decision on which type of system to ultimately procure depends on numerous factors including specific performance objectives, funding availability, schedule requirements, and organizational priorities. Aerospace studies were only able to address a subset of these issues. This testimony was intended to provide the committee information and insight gained from analyses performed by Aerospace and does not constitute a recommendation for the development of systems supporting NASA or national needs.

Thank you for the opportunity to describe The Aerospace Corporation’s advanced launch system studies.

I stand ready to provide any further data or discussions that the committee may require.