Mechanical Components

Rapid-Chill Cryogenic Coaxial Direct- Acting Solenoid Valve

A commercially available cryogenic direct-acting solenoid valve has been modified to incorporate a rapid-chill feature. In the original application for which this feature was devised, there is a requirement to ensure that at all times, the valve outlet flow consists entirely or mostly of liquid; that is, there is a requirement to minimize vaporization of cryogenic liquid flowing through the valve. This translates to a requirement to chill interior valve surfaces in contact with the flowing liquid.

Posted in: Mechanical Components, Briefs, TSP

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On Release of Microbe-Laden Particles From Mars Landers

A paper presents a study in which rates of release of small particles from Mars lander spacecraft into the Martian atmosphere were estimated from first principles. Because such particles can consist of, or be laden with, terrestrial microbes, the study was undertaken to understand their potential for biological contamination of Mars. The study included taking account of forces and energies involved in adhesion of particles and of three mechanisms of dislodgement of particles from the surface of a Mars lander: wind shear, wind-driven impingement of suspended dust, and impingement of winddriven local saltating sand particles. Wind shear was determined to be effective in dislodging only particles larger than about 10 microns and would probably be of limited interest because such large particles could be removed by pre-flight cleaning of the spacecraft, and their number on the launched spacecraft would thus be relatively small. Dislodgement by wind-driven dust was found to be characterized by an adhesion half-life of the order of 10,000 years — judged to be too long to be of concern. Dislodgement by saltating sand particles, including skirts of dust devils, was found to be of potential importance, depending on the sizes of the spacecraft-attached particlesand characteristics of both Mars sand-particle and spacecraft surfaces.

Posted in: Mechanics, Mechanical Components, Briefs

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Retaining Device for the Interior Structure of a Spacecraft Payload

Device protects without penalizing interior space. A device denoted as a bumper assembly for a spacecraft payload container comprises an interior structure surrounded by skin or some other protective enclosure (see figure). When arranged with three or more like assemblies, this bumper assembly is designed to secure the interior structure within a payload’s protective enclosure during the stresses endured in flight and, if required, recovery of the payload. Furthermore, proper use of this innovation facilitates the ability of designers and engineers to maximize the total placement area for components, thus increasing utilization of very valuable and limited space.

Posted in: Mechanical Components, Briefs, TSP

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Tool for Torquing Circular Electrical-Connector Collars

A simple tool exerts a strong grip. An improved tool has been devised for applying torque to lock and unlock knurled collars on circular electrical connectors. The tool was originally designed for, and used by, astronauts working in outer space on the Hubble Space Telescope (HST). The tool is readily adaptable to terrestrial use in installing and removing the same or similar circular electrical connectors as well as a wide variety of other cylindrical objects, the tightening and loosening of which entail considerable amounts of torque.

Posted in: Mechanics, Mechanical Components, Briefs, TSP

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Recovering Residual Xenon Propellant for an Ion Propulsion System

Most of the otherwise unusable xenon is recovered. Future nuclear-powered Ion-Propulsion- System-propelled spacecraft such as Jupiter Icy Moon Orbiter (JIMO) will carry more than 10,000 kg of xenon propellant. Typically, a small percentage of this propellant cannot be used towards the end of the mission because of the pressure drop requirements for maintaining flow. For large missions such as JIMO, this could easily translate to over 250 kg of unusable xenon.

Posted in: Mechanical Components, Briefs, TSP

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System Would Detect Foreign-Object Damage in Turbofan Engine

Vibration-sensor and gas-path-analysis data would be fused. A proposed data-fusion system, to be implemented mostly in software, would further process the digitized and preprocessed outputs of sensors in a turbofan engine to detect foreign-object damage (FOD) [more precisely, damage caused by impingement of such foreign objects as birds, pieces of ice, and runway debris]. The proposed system could help a flight crew to decide what, if any, response is necessary to complete a flight safely, and could aid mechanics in deciding what post-flight maintenance action might be needed.

Posted in: Mechanical Components, Briefs, TSP

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Cargo-Positioning System for Next-Generation Spacecraft

A report discusses a proposed system for mounting loaded pallets in the cargo bay of a next-generation space-shuttle-like spacecraft, such that the center of mass of the cargo would lie within a 1-in. (2.54- cm) cube that would also contain the center of mass of the spacecraft. The system would include (1) an algorithm for planning the locations of the pallets, given the geometric and weight properties of the pallets, and the geometric restrictions of the cargo bay; (2) quick-connect/ quick-disconnect mounting mechanisms similar to those now used on air hoses; (3) other mounting mechanisms, comprising mostly spring-loaded pins, in a locking subsystem that would prevent shifting of the pallets under load; and (4) mechanisms for performing fine position adjustments to satisfy the center-of-mass requirement. The position-adjusting mechanisms would be motor-driven lead-screw mechanisms in groups of three — one for positioning each pin of the locking subsystem along each of three mutually perpendicular coordinate axes. The system also would include a triple threaded screw that would provide compensation for thermal expansion or contraction of the spacecraft.

Posted in: Mechanical Components, Briefs, TSP

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