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To sustain the extra-vehicular activity (EVA) rate required to assemble and maintain the International Space Station (ISS), we must enhance our ability to plan, train for, and execute EVAs. An underlying analysis capability must be in place to ensure EVA access to all external worksites either as a starting point for ground training, to generate information needed for on-orbit training, or to react quickly to develop contingency EVA plans, techniques, and procedures. This paper describes a potential flight experiment for application of custom human modeling analysis to plan and train for EVAs to enhance space station functionality and usability through assembly and operation.

The McDonnell Douglas Delta family of launch vehicles, in its more than 30-year history, has proven to be the most reliable spacecraft deployment platform for both the US government and the private sector. This success is due to the continuous and focused application of advanced, affordable engineering and manufacturing technologies in all stages of the design, fabrication, assembly, quality assurance, and launch. One of the recent technological breakthroughs that has enhanced the Delta's service capabilities is the development and use of large composite structures in critical components. Among these structures is the payload fairing, which acts as a protective shroud for the spacecraft. Traditional composite manufacturing techniques, however, are very labor-intensive and time-consuming.

Bioreactor technology for waste water reclamation in a regenerative life support system (RLSS) is currently being developed by a team of NASA and major aerospace companies. To advance this technology, several activities are being performed concurrently; these include conducting small-scale studies and developing computer models. Small-scale studies are being performed to characterize and enhance the bioprocesses occurring within the bioreactor. New bioreactor configurations have been investigated which improved total organic carbon degradation as well as nitrification, the polishing step which converts nitrogenous wastes into forms that are easily removable from the water. Small-scale studies have also been performed using an activated sludge reactor demonstrating that TOC reduction and nitrification can occur in a single reactor. Computer models have been developed to guide the laboratory studies and to assist in full-scale system design.

Although aircraft tires are traditionally tested on external dynamometers, the effects of the curved test surface on normal contact pressure distribution and footprint area of a tire have not been previously addressed. Using the Tire Force Machine (TFM) at the Wright Laboratory Landing Gear Development Facility (LGDF), trends for pressure distribution and footprint area were investigated for concave, convex and flat plate surfaces. This evaluation was performed using the F-16 bias, F-16 radial and B-57 bias main landing gear tires at rated load and inflation pressures. The trends for overall tire footprint behavior indicate that the more convex the surface, the smaller the contact area and the larger the normal contact pressures. Conversely, the more concave the surface, the larger the contact area and the smaller the normal contact pressures. Based on these results, the study recommends a 168″ diameter concave (internal roadwheel) dynamometer for tire wear/durability tests.

Tactical aircraft have tire lives as low as 3-5 landings per tire causing excessive support costs. The goal of the Improved Tire Life (ITL) program was to begin developing technology to double aircraft tire life, particularly for tactical aircraft. ITL examined not only the tire, but also aircraft/landing gear design, aircraft operations, and the operational environment. ITL had three main thrusts which were successfully accomplished: 1) development of an analytical tire wear model, 2) initiation of technology development to increase tire life, and 3) exploration of new and unique testing methods for tire wear. This paper reports the work performed and the results of the USAF sponsored ITL program.

This paper describes the capabilities of using a time domain analysis to simulate the electrical waveforms on the MIL-STD-1553B data bus using the circuit simulation program SPICE. This simulation was developed to analyze the various data bus architectures of the Space Station Freedom (SSF) propulsion module system. The advantages of this model over frequency domain models is that the waveform is directly calculated, not synthesized, providing a more accurate and detailed waveform representation. Also, nonstandard configurations and effects can be modeled with accurate simulation results. The output of the simulation is an electrical waveform which can be measured at any point in the bus architecture. Therefore it is possible to see the distortion effects on the transmitted signal's waveform at any point on the MIL-STD-1553B data bus. This model accurately simulates the stray impedance effects of all bus components, and is flexible enough to examine any transmitted waveform.

The paper describes the development, implementation, and benefits of a real-time statistical process control (SPC) data acquisition and response system. The system has been installed on four production CNC riveters and provides enhanced, in-process control of automated fastening machine performance. Each system employs commercially available SPC components. These components, coupled with real-time data acquisition computers, have been integrated with the riveter's controllers and sensors to detect process anomalies as they occur. Real-time knowledge of fastening machine performance is the benefit of this system's approach to SPC. Fastener quality is ensured during the fastening cycle, not after sequences (and perhaps hundreds of rivets) have been completed.

The NASA Johnson Space Center has plans to integrate a Solid Amine Water Desorbed (SAWD II) carbon dioxide removal subsystem into the Variable Pressure Growth Chamber (VPGC). The SAWD II subsystem will be used to remove any excess carbon dioxide (CO2) input into the VPGC which is not assimilated by the plants growing in the chamber. An analysis of the integrated VPGC-SAWD II system was performed using a mathematical model of the system implemented in the Computer-Aided System Engineering and Analysis (CASE/A) package. The analysis consisted of an evaluation of the SAWD II subsystem configuration within the VPGC, the planned operations for the subsystem, and the overall performance of the subsystem and other VPGC subsystems. Based on the model runs, recommendations were made concerning the SAWD II subsystem configuration and operations, and the chambers' automatic CO2 injection control subsystem.

The size and complexity of Space Station has driven the need for an accurate, reliable analytical tool to assess the extravehicular activity (EVA) crew interfaces at the worksite. On previous spacecraft, each worksite was developed and validated through Neutral Buoyancy underwater testing by the crew using mockups. For spacecraft requiring a significant amount of EVA over large areas, like Space Station, the cost of conducting underwater tests for each of the many hundred worksites becomes prohibitive. Therefore, limited testing must be augmented by accurate graphical analysis. The Unigraphics II, which is the Computer Aided Design (CAD) system for the International Space Station Alpha (ISSA) Product Group 1 design, was selected and developed. It has a major advantage of easy and rapid access to the accurate and updated Space Station design. The design can be rapidly obtained electronically from layouts, detail drawings, assembly drawings or the Electronic Development Fixture (EDF).

The objective of this paper is to present results of MDA's payload vibration isolation system research and development program. A unique isolation system with passive or active capabilities designed to provide isolation down to 10-6 g was developed and tested in our 1-g testbed under simulated microgravity conditions. Fluid and electrical umbilicals are also included in the system. The established isolation system performance requirements were met and the testbed data were used to refine our analytical models for predicting flight performance. Simulations using an updated Space Station configuration showed that the payload microgravity requirement can be met by upgrading the hardware from laboratory to flight tolerances and improving the control system design. The next step is to flight test the systems verified in 1 g on the STS/SPACEHAB using a middeck locker size development unit.