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Technical Paper

Development of a Fluid Systems Servicer (FSS) for the International Space Station

1997-07-01
972407
The Fluid Systems Servicer (FSS) is designed to drain, purge, fill, and recirculate fluids while performing on-orbit start-up, scheduled, and unscheduled maintenance for fluid lines on the International Space Station (ISS). The FSS will utilize space vacuum for purging operations, thus, providing essentially unpowered vacuum back-filling capability. There is also a fluids pump in the FSS which is used for draining and recirculating water. The recirculation mode fulfills an additional design requirement of removing gas bubbles by directing water through a static membrane separator. Several flex-lines and adapters which interface various ISS lines via self-sealing Quick Disconnects (QD), are part of the FSS assembly. The FSS has its own power cord enabling excellent transportability. This feature, as well as, the QD adapters, enables the FSS to be used anywhere on station for numerous servicing tasks.
Technical Paper

Analysis and Characterization of Mixed Alkyl Silane Self-Assembled Monolayers on Metal and Oxide Surfaces

1995-07-01
951684
Alkyl silane amphiphiles form robust Self-Assembled Monolayers (SAMs) on stable oxide surfaces. Substrate surfaces of Ge, Si, and Ti can be modified by coating them with ultra-thin long-chain alkyl silane monolayers which are found to be very stable1. Titanium is especially interesting as it is a light, corrosion-resistant metal used in aircraft, spacecraft, and medical devices. In this study, mixed monolayers, composed of very similar alkyl silanes, differing only in chain length by about 5 angstroms (Å), were formed on silicon wafer substrates. Although the desired and expected result was random mixing of the monomers in the SAM, island aggregates of the longer monomer were observed with Atomic Force Microscopy (AFM). Since self-assembly of silanes on oxide is believed to be attained through strong covalent Si-O bonding at the substrate surface, inter-molecular thermodynamic forces between like molecules, or incomplete mixing of monomers may give rise to island formation.
Technical Paper

An Assessment of the Readiness of Vapor Compression Distillation for Spacecraft Wastewater Processing

1991-07-01
911454
Exhaustive testing and analysis of Vapor Compression Distillation technology has proven its overall readiness as a wastewater processor for the recovery of water in orbiting and interplanetary spacecraft. In conjunction with Boeing Aerospace and Electronics and the National Aeronautics and Space Administration, Life Systems' technical team has been focusing on verifying and improving performance characteristics, micro-gravity compatibility, reliability and maintainability aspects of the Vapor Compression Distillation design. Amassing thousands of hours of testing and recent breakthroughs in the area of peristaltic pump design, product water conductivity sensing and gas/liquid separation concepts have substantially increased the engineering and scientific database that has been accumulating over the past 29 years.
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