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An approach to the isolation and concentration of volatile organic compounds from a water sample prior to chemical analysis in a microgravity environment has been previously described (Reference 1). The Volatile Organics Concentrator (VOC) system was designed for attachment to a gas chromatograph/mass spectrometer (GC/MS) for analysis of the volatile organics in water on Space Station Freedom. The VOC concept utilizes a primary solid sorbent for collection and concentration of the the organics from water, with subsequent transfer using nitrogen gas through a permeation dryer tube to a secondary solid sorbent tube. The secondary solid sorbent is thermally desorbed to a gas chromatograph for separation of the volatiles which are detected using a mass spectrometer.

The process used to identify, select and design an approach to the isolation and concentration of volatile organic compounds from a water sample prior to chemical analysis in a microgravity environment is described. The Volatile Organics Concentrator (VOC) system described in this paper has been designed for attachment to a gas chromatograph/mass spectrometer (GC/MS) for analysis of volatile organics in water on Space Station. In this work, in order to rank the many identified approaches, the system was broken into three critical areas. These were gases, volatile separation from water and water removal/GC/MS interface. Five options involving different gases (or combinations) for potential use in the VOC and GC/MS system were identified and ranked. Nine options for separation of volatiles from the water phase were identified and ranked. Seven options for use in the water removal/GC column and MS interface were also identified and included in overall considerations.

Solar proton events (SPEs) are preceded by the optical, radio, and X-ray emissions of solar flares. Thus the capability for providing early warning of SPEs is possible if the particle fluxes can be correlated with the electromagnetic signatures from the sun. We have developed and refined the correlations of the peak proton flux at geosynchronous orbit with the solar X-ray emissions using data collected by the GOES spacecraft and supplied by NOAA. We have used data from over most of solar cycle 21 and the early portion of cycle 22 to extend the data base and improve the correlations. A power law relationship has been assumed between the peak proton flux and the X-ray fluence in both the 0.5-4 and 1-8 Angstrom bands of the GOES X-ray sensors. The correlation coefficients are approximately the same for both X-ray energy bands. We have also examined and obtained the correlation between the X-ray energy and peak proton flux at different proton energies.

A family of Electrical Power System (EPS) analysis tools that is generic in nature have been developed to perform EPS analyses to evaluate the design and operation of a space vehicle from an electrical power perspective. The tools were developed by the Electrical Systems Analysis Task of McDonnell Douglas Space Systems Company, Houston Division (MDSSC-Houston) under the Applications and Analysis Support Contract (AASC) in support of the Systems Engineering Division/ET at NASA/Johnson Space Center (JSC) within the Engineering Directorate. To date the tools have been used to analyze the power systems on the Space Station Freedom (SSF), Orbital Maneuvering Vehicle (OMV), and Assured Crew Return Vehicle (ACRV), but are adaptable to any space vehicle.

Improved understanding of the orbital debris environment in recent years and the prospect of significantly increased extravehicular activity (EVA) for the assembly and maintenance of Space Station Freedom have resulted in increased focus on the potential hazards to the EVA crewmembers from the micrometeoroid and orbital debris environments. While the hazards associated with any individual EVA remain extremely small, some estimates of the cumulative risks over the anticipated duration of the Space Station Program have been appreciable. These estimates, based on analytical models which treat the micrometeoroid and debris environments as isotropic, suggest the desirability of substantially modifying either the extravehicular mobility unit (EMU) or the planned EVA profiles for space station to reduce these hazards.

The objective of the Thermal Control System Automation Project (TCSAP) is to develop an advanced Fault Detection, Isolation, and Recovery (FDIR) capability for use on the Space Station Freedom (SSF) External Active Thermal Control System (EATCS). Real-time monitoring, control, and diagnosis of the EATCS will be performed with a Knowledge-Based System (KBS). The EATCS provides heating, cooling, and control necessary to maintain elements, systems, and components within their required temperature ranges. The EATCS design has evolved from the single-phase fluid system used in Apollo and Space Shuttle to a two-phase system (ammonia liquid and vapor mixture) on SSF. Both active and passive components of the EATCS can potentially fail or become blocked. As a result, a variety of failure modes exist. When this is combined with the continuous range of normal operating conditions, EATCS management becomes very complex.

An approach to the isolation and concentration of volatile organic compounds from a water sample prior to chemical analysis in a microgravity environment has been previously described (Reference 1). The Volatile Organics Concentrator (VOC) system was designed to attach to a gas chromatograph/mass spectrometer (GC/MS) for analysis of volatile organic compounds in water on Space Station Freedom. The VOC utilizes a primary solid sorbent for collection and concentration of the volatile compounds, transfer of the volatiles through a permeation dryer to a secondary solid sorbent, followed by thermal desorption of volatiles from the secondary sorbent onto a GC/MS system. Fabrications and preliminary testing of the VOC breadboard using a gas chromatography equipped with flame ionization detector has been previously described (Reference 2). These results have indicated that the VOC will meet or exceed the goals set for the program.

In the early stages of development for Space Station Freedom (SSF) the primary means for connecting the Shuttle to SSF was through docking, with Shuttle berthing to be used only in the early building stages. The docking mechanism, an actively controlled load alleviation device, was to be used to limit the docking loads to an acceptable level. In late 1990, as a weight saving measure, Shuttle docking was deleted from the program and Shuttle berthing utilizing the Remote Manipulator System (SRMS) became the primary means of connecting the Shuttle to SSF, thus transmitting the full impact loads into the primary structure of SSF and Shuttle. More recently in early 1992, docking has been brought back into the program for post stage 5 configurations. A solution sequence for transient dynamic analysis with modal initial conditions was developed.

Modal contribution indicator which represents the percent contribution of each mode to the total response was used to assess the convergence of the predicted critical structural member loads using Rayleigh-Ritz approach. Two important parameters in the dynamic analysis, dominant mode and truncation frequency, may be effectively identified by the modal contribution indicator. The percent modal contribution of a mode may vary if a different truncation frequency was used in the calculation of the structural member loads. In general, a mode with a relatively larger modal contribution indicator value is considered to be a dominant mode and is significant and essential for predicting accurate loads. An appropriate truncation frequency to ensure the convergence of the load can be determined by examining the ratios of the modal contribution indicators of each mode for various selected truncation frequencies.