Special Coverage


MEMS Gyroscope with Dual Interferometric Sense Elements

This sensing technique enables the use of a large proof mass with very low thermomechanical noise. John F. Kennedy Space Center, Florida High-performance inertial sensors, such as ring laser gyroscopes or fiber optic gyroscopes, have sufficient performance to enable “dead reckoning” navigation for adequate periods of time. Smaller microelectromechanical system (MEMS) inertial sensors, such as MEMS gyroscopes and MEMS accelerometers, typically have relevant performance characteristics that are 10 or 100 times worse than high-performance inertial sensors. As a result, these small MEMS inertial sensors must be aided by a global positioning system (GPS) if they are to be used for navigation.

Posted in: Briefs, TSP, Sensors


MMOD Risk Mitigation Technology for Spacecraft Thermal Protection Systems

The ingestion of high-temperature plasma through a small breach could be prevented by providing adequate counter pressure. Lyndon B. Johnson Space Center, Houston, Texas The proposed concept uses sensors to detect high-temperature plasma ingestion during entry through a breach in the thermal protection system (TPS) caused by a micrometeoroid orbital debris (MMOD) impact. It uses consumables usually available on human-rated spacecraft such as gaseous nitrogen (or helium) and water to maintain spacecraft structural integrity by keeping it within the temperature limits via an evaporative cooling effect and to equalize the internal and external pressures to prevent high-temperature plasma from flowing further into unintended areas. Once a breach was detected, the system could be activated autonomously or manually by the flight crew, or by telemetry from the ground crew.

Posted in: Briefs, TSP, Detectors, Sensors


Shock-Sensing Apparatus

This apparatus enables easy and reliable shock detection and localization in high-speed inlets of aerospace vehicles. John H. Glenn Research Center, Cleveland, Ohio Acompact shock-sensing device, which employs an innovative light sheet generator, has been created. The device may be used either as a solo aerodynamic shock detector or in combination with a scanning mode shock sensor. This permits easy detection and tracking of unstable and traveling shocks in supersonic inlets.

Posted in: Briefs, TSP, Lasers & Laser Systems, Detectors, Sensors


Purifying Nanomaterials by Dissolving Excess Reactants and Catalysts in Ferric Chloride

Liquid phase temperature salts dissolve metallic catalysts like Fe, Co, or Ni, and “wash” them away. John H. Glenn Research Center, Cleveland, Ohio Physical and chemical properties of nanomaterials are known to be significantly different from those having larger crystallites (i.e. bigger than nano), but with the same chemical compositions. Optimal uses of these new nanomaterial properties will likely result in engineering materials that are better than what is available today. Before this can happen, characterization of the physical and chemical properties of nanomaterials is needed.

Posted in: Briefs


White, Electrically Conductive, Radiation-Stable, Thermal Control Coating

Goddard Space Flight Center, Greenbelt, Maryland A highly reflective, white conductive coating system was developed using a layered approach with a combination of commercially available white conductive pigments within a conductive binder system. The top coating is a space-stable, radiation-resistant, highly reflective coating that has been tailored to provide optimum reflectance properties and meet vacuum thermal surface resistivities. The combined layer is a mixture of a highly reflective, electrically dissipative coating and a moderately reflective but highly conductive pigment in a conductive binder. A second, underlying layer of conductive white coating offers optimum adhesion to metal substrates and the topcoat. The system vacuum resistivity at room temperature is approximately 1 × 109 ohms/sq, and has a solar absorptance of less than 0.13 as measured on a Cary 5000 spectrophotometer.

Posted in: Briefs, TSP, Thermoelectrics, Coatings & Adhesives


Plasma-Assisted Thin Film Coatings to Create Highly Hydrophobic Porous Structures

Multiple samples can be coated in this manner. John H. Glenn Research Center, Cleveland, Ohio Gas-distribution layers (GDLs) are water-management structures used in fuel cells and electrolyzers. GDLs are critical components that prevent flooding of the fuel cell electrode by product water, thus preserving open channels for reactant gas to reach the electrode. Typically, GDLs are electrically conductive papers (metal or carbon) having a fine pore structure. Extremely fine pores in some GDL materials are difficult to fully infiltrate with Teflon (PTFE). These materials are typically wet-proofed by coating with hydrophobic materials (e.g. PTFE). This is usually accomplished by immersing the raw paper in a PTFE emulsion. Completeness of wet-proofing by immersion in emulsion can be limited, because fine pores will filter out the PTFE particles.

Posted in: Briefs, TSP, Coatings & Adhesives


High-Performance Photocatalytic Oxidation Reactor System

Airborne volatile organic chemicals are oxidized using blue LEDs, fiber optics, and visible light-activated catalysts for space and terrestrial air purification. Marshall Space Flight Center, Alabama As crewed space missions extend beyond low Earth orbit, the need to reliably recover potable water is critical. Aboard the International Space Station (ISS), the water is recycled from cabin humidity condensate, urine distillate, and hygiene wash wastes. In spacecraft cabin air environments, off-gassing from equipment, human metabolism, and human personal care products contributes to significant airborne concentrations of volatile organic compounds (VOCs). These polar and water-soluble compounds ultimately dissolve into the humidity condensate and stress the process load, logistics costs, and lifecycle requirements of the water processing systems. The aim of this effort was to develop the High Performance Photocatalytic Oxidation Reactor System (HPPORS) technology for the destruction of airborne VOCs prior to reaching the water processing systems. This innovation will reduce the logistics costs and lifecycle requirements of water processing systems, and help extend NASA missions to include long-duration space habitation and lunar and Mars colonization missions.

Posted in: Briefs, Recycling Technologies, Remediation Technologies, Fiber Optics, Photonics