Aeronautics and Space Report of the President FY 1995 Activities


Space Flight and Space Technology

Space Shuttle Technology

The Space Shuttle's primary purpose in FY 1995 continued to be transporting people and cargo safely into low-Earth orbit. At the end of the year, NASA had four active orbiters in its fleet—Atlantis, Columbia, Discovery, and Endeavour. During FY 1995, Columbia completed its orbiter maintenance down period in the Palmdale, California, facility. As the year ended, technicians were preparing Discovery for delivery to Palmdale for its down period. Technicians planned to modify Discovery so that it will be able to dock with the Russian Mir space station and assemble the International Space Station.

The Space Shuttle program initiated a major restructuring that will focus space flight operations under a single prime contractor, among other changes. NASA civil service personnel are to begin retreating from the routine daily operations and change their role to auditing and providing independent assessments of Shuttle problems. NASA managers are to retain sufficient technical insight into contractor activities to ensure a safe commitment to flight, in addition to managing all Shuttle hardware development and safety improvements.

NASA engineers continued redesigning the external tank to reduce structural weight and thus improve the performance of the Shuttle system. The redesign involved substituting aluminum lithium for the existing aluminum alloy to take advantage of the new material's greater strength per weight. As of the end of FY 1995, the first launch of the redesigned super lightweight tank was scheduled for late in calendar year 1997.

Space Shuttle Main Engine project managers aggressively pursued the development and implementation of safety and reliability improvements in FY 1995. In the current engine, technicians upgraded five major components in two block changes. Block I incorporates the new phase II+ powerhead, the single-coil heat exchanger, the alternate high-pressure fuel turbopump, and the large throat main combustion chamber. The Block I engine completed the certification program in May 1995 and had its first flight in July 1995. The first of four development/certification large throat main combustion chambers was delivered during FY 1995 and is to be incorporated into the first development Block II engine for testing. Engineers involved in the oxidizer turbopump development successfully resolved all of the major technical problems they encountered early in development. Due in large part to this success, Congress approved the resumption of development work on the fuel turbopump, which had been in caretaker status since 1991. Engineers and technicians began development testing of the Block II engine at the end of the fiscal year, and at that time the Block II configuration was scheduled to enter service in September 1997.

The Solid Rocket Booster successfully supported the six Shuttle flights during FY 1995. Redesigned Solid Rocket Motor nozzle production remained in Utah. NASA had wanted to move it to the former Advanced Solid Rocket Motor (ASRM) site in Mississippi, but NASA ended up closing this ASRM site and transferring control of the site to the State of Mississippi.

In the area of Space Shuttle systems integration, the Day-of-Launch I-Load Update (DOLILU) system was available on all FY 1995 missions. This system updates the flight trajectory to account for actual winds on launch day. In June 1995, software engineers successfully implemented the DOLILU II system, which also incorporates the main engine control tables, solid rocket trim data, and aerodynamic control data on launch day. This system further optimizes the ascent trajectory of the Shuttle and eliminates significant flight-to-flight trajectory design activities. Integration efforts during FY 1995 also included analyses of structural loads; resolution of in-flight anomalies, waivers, and changes; and software development and testing for the control of each mission. To support the International Space Station mission requirements, NASA began to identify, develop, and schedule Shuttle performance enhancements. Engineers developed systems integration plans to ensure the orderly implementation of these enhancements into the Space Shuttle program. These plans specified design analyses and test requirements to provide definition of flight margins. Engineers and technicians also completed on schedule several systems analyses to certify the safety of the Shuttle's performance enhancements and to ensure compatibility of design modifications to the external tank, main engines, and the orbiter. At the end of the fiscal year, Shuttle managers had specified all of the necessary enhancements to support the first Shuttle-launched International Space Station assembly flight, which is scheduled for December 1997.

Engineers at Kennedy Space Center (KSC) redesigned the launch and landing ground support equipment for the Shuttle to eliminate the use of ozone-depleting chlorofluorocarbons (CFC). Two key items are the portable purge units, which purge the Shuttle orbiter immediately after landing, and the Shuttle launch pad environmental control system, which provides clean, conditioned air to the launch vehicle elements and the payload changeout room. KSC engineers also began developing aqueous cleaning and cleaning verification methods to reduce CFC freon-113 usage and associated release to the atmosphere. KSC managers plan to eliminate totally the use of CFC freon-113 by the end of 1997.

Engineers began developing a propulsion advisory system as an advanced software tool to aid in data analysis and problem resolution during launch, landing, and dynamic testing. Propulsion system experts used this software to monitor a wide range of data to assess propulsion system health. This software includes an intelligent graphical interface and display capability that provides enhanced data representation, including saturation curve plotting. The new software system has simplified the task of performing trend analysis, system health monitoring, and diagnosis.

Approximately 36,000 photographs were taken of critical Space Shuttle mission closeout activities. Technicians began to digitize these photos and store them on electronic media that provide better storage, records management, and retrieval. Archivists hoped to configure a system in which users can review these photos online in their offices to increase the ease of efficiency of future closeout activities.


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Curator: Lillian Gipson
Last Updated: September 5, 1996
For more information contact Steve Garber, NASA History Office,
sgarber@hq.nasa.gov