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Air University Review, January-February 1971
Lieutenant Colonel Donald L. Steelman
During the past decade the space program of the United States has matured greatly. From the meager beginning of orbiting a satellite weighing three pounds, the nation has advanced to significant accomplishments in both manned and unmanned space exploration.
Attaining a reliable space capability and achieving the lunar landing goal, however, have been extremely costly, the total expenditure for space programs during the decade being approximately $50 billion. During the sixties the U.S. launched nearly 300 payloads into earth orbit with a cumulative payload weight of approximately 3½ million pounds. The cost of delivering the early satellites to orbit was approximately $1 million per pound, compared with present costs of about $1000 per pound. The decrease in cost is related to size, production rate, and improved launch-vehicle performance through advanced technology. But today, as in the past decade, every launch vehicle is expended after its initial use, as well as every payload because the payloads cannot be maintained or reused. The high cost of putting things into orbit and their inaccessibility once they are in space have been limiting factors on the nation’s space activity thus far. The cost will become even more constraining in the future because of other high-priority national programs that will require attention and funding.
report of the Space Task Group
Recognizing the need to plan effectively the nation’s future space activities, the President established a Space Task Group (STG) in 1969 to consider goals and objectives for the period after Apollo. In its report the STG, considering the need to decrease the high cost of space operations, recommended that a Space Transportation System (STS) be developed that would be a major improvement over the present systems in terms of cost and operational capability. It would be designed to carry men, equipment, supplies, and other spacecraft to and from orbit and would support both Department of Defense (DOD) and National Aeronautics and Space Administration (NASA) missions.
The STS concept that has evolved from the STG activities and from preliminary NASA and Air Force studies and analyses is a two-stage reusable vehicle, called the Space Shuttle, to be used for carrying payloads from earth to low-earth orbit and return, and a reusable Orbit-to-Orbit Shuttle (OOS) for transferring spacecrafts to high-energy orbits. The first stage of the Space Shuttle is a booster that will perform initial acceleration for the system. The second stage is the orbiter, which will continue into orbit and will contain the payload compartment that accommodates the OOS and/or spacecraft.
A flexible, fully reusable space transportation system will reduce not only launch-vehicle costs but also payload costs as a result of repair and reuse capability and reduction in design and testing constraints. To the DOD, which spends approximately $1.7 billion per year for space programs, the attractiveness of economy in space operations is evident. Space systems within the DOD must compete with other means or operational modes for satisfying specific mission objectives. Thus an economical Space Transportation System with proper capabilities and operational flexibility will enable space activities to become more competitive. Such a system is expected to have a profound impact on space operations and probably an effect on the cost of DOD space systems.
intended joint DOD/NASA use
For conducting present space operations, the DOD employs the Scout, Thor, Atlas, and Titan III as basic Standard Launch Vehicles (SLV’s). These SLV’s, coupled with upper stages such as the Agena, Burner II, Tran-stage, or NASA Centaur, are used in various combinations to satisfy launch-vehicle requirements for the DOD, other agencies such as NASA, Environmental Science Services Administration (ESSA), commercial organizations (e.g., ComSat), and foreign nations (United Kingdom, Germany, Italy, etc.). Additionally, NASA uses the Saturn family of vehicles to accomplish its manned launches.
It is for the potential replacement of this stable of expendable launch vehicles that a national STS is proposed. Because of the many potential multipurpose applications, the STS must have a capability to satisfy both DOD and NASA space operations. Preliminary studies have shown that, because of the R&D costs, neither NASA nor DOD can separately justify or amortize the cost of the system based on their respective traffic forecasts. On the other hand, the studies have indicated that the combined needs of both agencies are sufficient to make the development of STS very attractive.
In February 1970 NASA Administrator, Dr. Thomas O. Paine, and the Air Force Secretary, Dr. Robert C. Seamans, Jr., signed an agreement that established a NASA/Air Force STS Committee, with four members from each agency, to review and plan the development phase of the Space Shuttle. Since NASA is the executive agent for the development of the Space Shuttle, the primary tasks at the present time for the Air Force, as DOD’s agent, are to coordinate Air Force activities that can contribute to that development, to establish DOD performance requirements, and to influence the design in such a way that DOD’s space needs can best be achieved.
Headquarters USAF establishes policy and provides direction for Air Force participation in Space Shuttle development. Coordination of all related activities within the Air Staff is the responsibility of the Directorate of Space, DCS/R&D. This Directorate maintains an in-depth understanding of the planning effort and status of Space Shuttle activities, coordinates supporting R&D activities, and insures that military requirements are properly considered in the shuttle design. From a policy point of view, the Directorate of Space coordinates with NASA on shuttle activities within the same general framework as on other areas of mutual interest to the Air Force and NASA. The Director of Space serves as a member of the NASA/USAF STS Committee.
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Figure 1. Size comparison of the Space Shuttle and existing flight systems
Outside the Air Staff, a variety of Air Force organizations participate in STS activities. In Headquarters Air Force Systems Command these activities are coordinated by an STS office under the DCS/Development Plans. Field activities for the STS are conducted within the Development Planning Office of the Space and Missile Systems Organization (SAMSO ). In addition to these offices, Air Force members participate in the various technical and technology planning panels established by NASA to define and coordinate technology programs necessary to support the development of the shuttle. The Air Force has also participated in review of the NASA Phase B Shuttle System Definition and Engine Requests For Proposal (RFP’s) and has assisted in evaluation of industry responses.
shuttle studies and characteristics
In May 1970, Phase B (preliminary design) study contracts for the Space Shuttle were awarded to two industry teams by NASA. These eleven-month studies will define the Space Shuttle system and are expected to provide a better understanding of the technical approach, scope, timing, and cost of the shuttle program. These studies, along with studies and analyses of space applications, operational impacts, and capabilities which the Air Force is conducting, should provide a better insight into the utility of the shuttle concept for the Department of Defense.
DOD interest in the shuttle lies in its potential for reducing the costs of space operations, achieving beneficial effects on payload design, and increasing mission flexibility and capability. If the shuttle system that evolves is to be useful to the DOD, it must be capable of satisfying these objectives. Accordingly, certain shuttle characteristics are vital to DOD mission needs in the areas of communications, meteorology, navigation, surveillance, and others.
To satisfy future DOD needs, the shuttle should have adequate payload capability to accomplish presently forecasted launches as well as the undefined space launches of the future. The operational characteristics, weight, and volume requirements of future payloads are likely to be varied, and a new STS should satisfactorily handle any reasonable variations. The new system should also be able to accommodate a variety of payloads for total launch cost less than that of present booster systems. Because a large number of DOD systems require that payloads be transferred from low orbit to high-energy orbits, it is necessary that the propulsive stage for the transfer to high orbits and back be considered as part of the shuttle payload. Thus, the payload bay should be sized in length and diameter to insure that payloads required for projected systems can be accommodated.
Since the first shuttle system, because of its development cost and time, will most likely be in use for at least twenty years, adequate consideration should be given to designing a vehicle to meet forecasted systems launches and allow for payload growth. Experience has shown that early versions of transportation vehicles are undersized by the time they are built and cannot accommodate normal payload growth. Air Force analyses have shown that the shuttle, to meet national needs, should have a capability of approximately 40,000 pounds equivalent payload in a 100-NM polar orbit with a payload bay approximately 15 feet in diameter and 60 feet long. Trade-offs of payload capability versus development costs and operational cost considerations must be carefully analyzed.
The shuttle should have minimum launch azimuth constraints, to permit maximum mission flexibility for a number of military space launches. It should have the ability to inject payloads into a variety of orbits, change its orbital parameters, and return from orbit under relatively unconstrained conditions. After performing a mission, it may have to return quickly to a predetermined landing site; therefore, the potential for a high hypersonic lateral maneuvering (crossrange) capability is required.
In addition to launch and return flexibility, military systems may require a capability for launch on short notice. Thus expeditious payload checkout and modular payload bays that are essentially unaltered from flight to flight are essential.
The Air Force believes that these desirable characteristics should be inherent in the shuttle design so that the system will not have to be redesigned early in its life cycle and so that the supporting equipment and facilities will have a long operational life. The theory that a small STS might be built in the near term and a larger version later does not appear to be an efficient or economical course of action. The Air Force is interested in system efficiency in terms of payload factors and operational aspects and does not propose a vehicle larger than necessary.
orbit-to-orbit shuttle
Coincident with the shuttle system definition effort, the design concept of the OOS is being considered because it, as part of the payload for the shuttle, has a significant impact on shuttle design considerations. In addition to volume and weight, there are many significant parameters affecting the design of both the shuttle and the OOS. Included are environmental conditions, electrical interface, computer commonality, guidance and navigation interaction, avionics, storage and ejection mechanisms, spacecraft sensors, and on-board checkout systems. Also, since the spacecraft or operational sensors should be designed for reusability, the capabilities for retrieval and refurbishment must be considered.
With the shuttle, the launch environment will be favorably altered. The more benign launch environment, more relaxed payload weight limitation, simpler payload integration, and ability to service payloads on-orbit or return them for diagnosis and repair may permit simpler, lower-cost designs for future spacecraft.
To achieve these payload design benefits, however, timely and effective planning must be accomplished so that spacecraft design concepts are time-phased with availability of the STS. The conduct and support of programmed essential military missions must not be jeopardized; therefore, the initial operational capability (IOC) date of the STS should be well established. Even though preliminary studies to date indicate a time-frame of the late seventies for the shuttle’s IOC, the results of the preliminary design definition studies will provide better planning information for predicting the availability date of an operational STS.
phase-out of present systems
Before the STS becomes the means for transporting payloads to and from space, consideration should be given to the proper phase-out of the expendable Standard Launch Vehicles. This changeover will have to be accomplished without disturbing military mission capability and at minimum program costs.
Coupled with the need to program and to plan for the phase-out of the SLV’s presently supporting the space programs, the phase-out of the attendant launch facilities should be considered. The DOD currently operates and maintains two Titan III launch complexes and one Atlas/ Agena complex at Cape Kennedy and ten different launch complexes at Vandenberg AFB to support the various space programs. A third supporting activity, the Satellite Control Facility (SCF), acquires and controls payloads on orbit. The impact of the STS on each of these facilities should be assessed at an early date.
Another factor concerning the phase-out of the Standard Launch Vehicles and the phase-in of the Space Transportation System is the program lead time involved. Because of the long lead time for procuring payloads and SLV’s and the time required to obtain approval and funds for the program, SLV’s scheduled to fly payloads in the 1974-75 time period are presently on contract. Procurement must be initiated in 1974 for vehicles that will fly in 1978, when the shuttle may become available. Because of the present uncertainty of the date when the STS will enter the inventory and the lead time involved in phasing out the SLV’s and associated facilities, it is obvious that very long-range planning must be accomplished if a smooth, effective, and economical phase-over is to be obtained.
Considerable planning and action have been under way by the DCS/R&D, and specifically the Space Directorate, on a continuing basis to consider these matters. As early as 1968 the Air Force and NASA, as part of the Aeronautics and Astronautics Coordinating Board (AACB ), performed a study of the launch vehicle requirements for DOD and NASA during the period 1970-80. Subsequent activity by the Manned Spaceflight and Launch Vehicle Panel of the AACB will include the necessary planning to phase out the SLV’s as the STS becomes operational. With this particular aspect in mind, a review of all vehicles, launch complexes, and user-agency requirements through the seventies was conducted, with NASA participation, in April 1970. Decisions were made and approaches agreed upon to lay out plans for reducing the number of launch vehicles and launch complexes to a minimum consistent with forecast mission and payload requirements until such time as the STS becomes operational. The end result will be a coordinated DOD/NASA long-range plan and course of action.
Once an economical and operationally effective Space Transportation System is developed, the Department of Defense expects to use it for its space operations. Thus, a very logical thought process and course of action need to be pursued in considering the STS development. The STS is not just another launch vehicle; rather, it is a system that provides for a radical change in the way we now approach and consider space applications, space missions, and space operations. First, in considering space applications, we should expand our horizons of the recent formative years and consider new space mission applications that could improve our means for economically accomplishing military missions. Second, an understanding and appreciation for the shuttle environment should be developed. This involves a completely new payload development philosophy. Third, the phase-in of the STS operations and the phase-out of present launch vehicles must be carefully considered to preclude weakening of the space posture. Future applications of the STS must be analyzed, and the total impact that an STS can have on future uses of the space environment should be explored.
Hq United States Air Force
Lieutenant Colonel Donald L. Steelman (M.S., George Washington University) is the staff officer responsible for the Space Transportation System in the Policy and Plans Group, Directorate of Space, DCS/R&D, Hq USAF, and also serves as the Secretariat for the NASA/USAF STS Committee. He has worked in weapons development and on phases of the Atlas booster, Agena vehicle, Ranger and Mariner projects, and Gemini and Apollo programs.
Disclaimer
The conclusions and opinions expressed in this
document are those of the author cultivated in the freedom of expression,
academic environment of Air University. They do not reflect the official
position of the U.S. Government, Department of Defense, the United States Air
Force or the Air University.
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