program elements. To insure that the many complex tasks being carried out simultaneously in widely separated locations are accomplished in accordance with systems requirements, and that all elements of the program are geared to achieving Space Shuttle operational status by the end of this decade, detailed operating procedures for systems integration have been developed and are being implemented.

Space Shuttle main engine

The Rocketdyne Division of Rockwell International which had been selected as the prime contractor for development of the Space Shuttle main engine, was awarded a definitive contract in April 1972. A "Preliminary Design Review" (PDR) was held in September 1972 and component development was initiated. Engineering effort is continuing to verify and improve engine performance. Orbiter/Integration contractor selection

After an exhaustive review of all technical and cost considerations involved. the Space Division of Rockwell International was selected in July 1972 as the prime contractor for Orbiter development and systems integration and contract was signed in August 1972.

During fiscal year 1973 considerable progress was made in initial Orbiter design and subsystem definition. The contractor is well on the way toward initiating hardware development, including definition of tooling and testing requirements with the Orbiter structures Preliminary Design Review (PDR) expected about the middle of fiscal year 1974. In addition, studies to verify new technological concepts continued and work was begun to establish operational requirements, such as simulation, training and other engineering support.

Program requirements for external tank (ET) and solid rocket booster (SRB) Definition of program requirements and specifications has progressed suffciently to make it possible to issue "Requests for Proposals" for the Externa Tank and the Solid Rocket Booster in the near future. It is planned to select the ET contractor by August 1973 and the SRB contractor in November 1973 In selecting these contractors, emphasis will be placed on the use of low-cost manufacturing techniques and tooling in order to reduce to a minimum the contribution of these systems elements to costs per flight. To assist in this endeaver, it is planned to fabricate and assemble external tanks at the U.S. Government-owned Michoud Assembly Plant in New Orleans, La.

Launch and landing site selection

A key decision made in 1972 was the selection of the Shuttle launch and landing sites. On April 4, 1972, Dr. James C. Fletcher, the NASA Administrator. announced that the Shuttle would operate from the Kennedy Space Center in Florida and Vandenberg Air Force Base in California. It was determined, after a thorough review of potential launch sites that those two existing facilities offered major advantages with respect to cost, safey, operational requirements and environmental impact. Operational requirements taken into consideration were booster recovery, launch azimuth limitations, latitude and altitude effects on launch and landing performance and abort constraints.

Environmental impact assessment

As required by the National Environmental Policy Act of 1969, and in accordance with guidelines established by the Council on Environmental Quality, & thorough analysis of the possible environmental effects of the Space Shuttle was made in 1972, in conjunction with other Federal agencies having responsibility in this area. Potential adverse consequences of Shuttle operations on the atmosphere and the oceans, as well as social effects were assessed and a detailed report was filed with the Environmental Protection Agency and submitted to Congress. In every case, these detailed studies of the effects on the atmosphere. water and noise by the Space Shuttle system showed that they were minimal and below allowable limits. Regardless of the fact that anticipated effects are below allowable limits, safeguards will be instituted to further minimize any potential environmental impact.

Cost analysis

Detailed cost analyses undertaken during the past year by NASA and several contractors indicate that the target costs of 5.39 billion in 1972 dollars (515 billion in 1971 dollars) for Shuttle development, and 10.5 million per flight (1971 dollars) are indeed realistic and can be achieved. These studies also showed that.

given the present mission and payload requirements, the configuration selected represents the best compromise between development and launch costs (figure 122). Other studies revealed that the use of the Shuttle as the principal means

of transportation and deployment could result in payload cost reductions by as much as 50 percent. Based on the currently anticipated utilization of the Space Shuttle, the reductions in payload costs coupled with the low cost of transportation would insure that the investment in Shuttle development could easily be returned over a 10-to-12 year flight program. If, as is likely, new, useful and economically beneficial mission possibilities open up during the 1980's because of the routine and quick access to space made possible by the Shuttle, the investment will be returned even more rapidly.

PLANS FOR FISCAL YEAR 1974

During the past years, a solid foundation was laid for the significant progress made in fiscal year 1973. Plans for next fiscal year call for a build-up in prime and sub-contractor manpower and the award of contracts for major elements of the Shuttle, notably the External Tank and the Solid Rocket Booster. Fiscal year 1974 funds will provide for an expanded scope of design, development and testing activities and for initiation of manufacturing of structural components and subsystems. Existing facilities for fabrication and testing will be modified to meet Shuttle program requirements. In fiscal year 1974 design and fabrication of tooling will begin and plans will be firmed up for system operations, training and support operations requirements. A more detailed discussion of accomplishments and future Shuttle program activities is contained in the following section of this statement.

SYSTEM DESCRIPTION

The Space Shuttle system consists of an Orbiter vehicle, an external hydrogen/ oxygen tank and twin solid rocket boosters (figure 123) (see p. 404). The Orbiter will look like a delta winged airplane, about the size of a DC-9 jet liner. It will have a payload bay that can accommodate payloads up to 4.5 meters (15 feet) in

diameter and 18 meters (60 feet) in length and weighing up to 29,500 kilograms (65,000 pounds). Doors on top of the compartment will open in orbit to permit deployment or recovery of spacecraft.

The Orbiter will normally carry a crew of four, including the pilot, a co-pilot, a systems monitor, and a payload specialist who will check out the payloads and deploy them in space. The Shuttle will accommodate up to 10 persons including the crew. All will travel in shirtsleeve comfort without space suits and undergo acceleration forces during launch and re-entry which are considerably less than those experienced during previous manned space flights. The Shuttle will permit scientists for the first time to accompany their experiments into space.

The Orbiter will be boosted into space through the simultaneous operation of two solid propellant booster rockets and three high pressure liquid oxygen/liquid hydrogen main engines. The booster rockets will detach at an altitude of about 48 kilometers (30 miles) and descend into the ocean by parachute, to be recovered. refurbished, and reused. The Orbiter with its three main engines and hydrogen/ oxygen propellant tank will proceed into orbit. The tank, which is expendable. will then be deorbited to a predetermined remote ocean site (figure 124). Upon completion of the mission, the Orbiter will reenter the atmosphere and land like a conventional airplane.

Progress made during fiscal year 1973 on all elements of the system provides a solid base for continued development in fiscal year 1974 (see figure 121, p. 401). Several years of feasibility and definition studies and a comprehensive technology program have resulted in the determination of system sizing and weights. selection of thermal covering for each area requiring heat protection, basic structural materials, and mission operations which would obtain the lowest practical cost-per-flight. Analyses and tests proceeded to investigate the design of the external tank and the size of the solid rocket boosters. Extensive testing. design, and hardware development efforts have led to a baseline configuration which gives assurance of meeting Shuttle cost and performance goals.

Upon completion of program plans, vehicle sizing and critical trade studies, system baseline specifications were established in 1972 at the Preliminary Requirements Review (PRR). This review resulted in the definition of data needed for procurement of the External Tank (ET), the Solid Rocket Booster SRB), and Orbiter subsystem requirements.

Vehicle requirements will be reviewed at the Systems Requirements Review (SRR) scheduled for early fiscal year 1974. The SRR will be followed by the award of contracts for the design and production of the external tanks and solid rocket boosters. In addition, the fabrication and assembly of the Orbiter will be started. leading to the scheduled First Horizontal Flight in early 1977 and o the First Manned Orbital Flight by the end of 1978 (see figure 119, p. 400). Contracting and hardware design is proceeding rapidly due to the availability of a sound technology base. The successful research, manufacturing, and operaional experience with the 120 and 156 inch solid rocket programs is directly applicable to the technology required for the shuttle solid rocket boosters; Saturn V technology and tooling will be used for ET development and producion; and, the use of a basic aluminum structure for the Orbiter eliminates the need for an expensive and potentially expensive metallurgical development program for improved structural materials.

Another key low-cost characteristic is the reduction of technical requirements wherever possible, Trade-off studies have already been successful in evealing several important ways in which this can be accomplished. For example, after it was determined that airbreathing engines would be necessary only for round ferry operations and early test missions, they were deleted from the Orbital missions. Such technical decisions to produce the least cost development and operational program is in agreement with the management principle to maximize the use of existing technology and to build the Shuttle to "hard" requirements. This resulted in cost consciousness permeating all trade studies and technical decisions.

ORBITER/INTEGRATION

Design and development of the Orbiter (figure 125) was initiated early in

fiscal year 1973. During the development phase of the program the prime contractor, the space division of the Rockwell International Corporation, is responsible for design, development, production, test and evaluation (DDT&E) of two Orbiter vehicles and support for the initial orbital flights. In addition the prime contractor has been assigned the task of supporting the Shuttle Program Office at JSC in integrating all elements of the Space Shuttle system.

During the past year efforts were devoted primarily to initial Orbiter vehicle design (figure 126), development, test, and engineering activities. Major Orbiter vehicle efforts in fiscal year 1973 include:

Award of the contract for obiter development and system integration, which includes completion of technical trade studies and the establishment of a base line configuration; establishment of program requirements (plans, schedule funding, manpower, facilities); preparation of systems specifications for Government-furnished equipment (solid rocket booster, external tank, air breathing engines); initiation of preliminary design-including structural diagrams and substructure layouts, materials selection, and cost optimization of fabrication; definition of thermal protection system interface requirements and initiation of procurement of reusable surface insulation materials; definition of subcontractor responsibilities; preparation of specifications for the avionics system configuration; completion of basic wind tunnel tests to support the systems requirements review; testing of structural components; initiation of vibration interaction tests and completion of forward fuselage model tests.

Wind tunnel studies were used extensively to determine the pattern of compli cated flow fields that exist about the Space Shuttle during ascent flight (figure 127). From such data, analytical estimates of aerodynamic pressure levels were made and applied to the structural design requirements and to the placement of components.