Tech Briefs

Multiplexer for Multiple Sensors in a Vacuum Chamber

The multiplexer reduces the number of required feedthroughs and ports. John F. Kennedy Space Center, Florida Vacuum chamber testing at large facilities can require hundreds of instruments, necessitating even more feedthroughs. The number of instruments and sensors that can be fed into a vacuum chamber is limited by the number of feedthrough ports dedicated to instrumentation. Thus high-pin-count, mil-spec-style feedthroughs have been developed, but these are all custom-made and also expensive to make and replace. The high-pin-count feedthroughs also make it much harder to troubleshoot individual wires in case of a problem. By using a multiplexer within the vacuum chamber, the number of wires required per instrument can be reduced to much less than one. The multiplication of wires from within a vacuum chamber allows a drastic increase in sensor and instrumentation channel count, while using the same number of sensor ports and feedthroughs within an existing vacuum system.

Posted in: Physical Sciences, Sensors, Briefs, TSP

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Analog Ceramic Isolated Voltage Sensor

John H. Glenn Research Center, Cleveland, Ohio Galvanic isolated monitoring of voltages for launch vehicle, missiles, and space-deployed systems can be very challenging. Radiation exposure makes use of optics-based sensors difficult, as they can latch-up and become corrupted by the radiation environment; such devices can moreover be thermally challenged. Magnetic transformer-based methods of isolated voltage measurement require shielding to prevent stray magnetic interference from degrading or corrupting the readings; moreover, magnetic-based solutions are unable to measure voltages down to DC levels.

Posted in: Physical Sciences, Sensors, Briefs, TSP

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Flexible and Erectable Magnetic Field Response Sensors

Langley Research Center, Hampton, Virginia The means to make a flexible and/or erectable magnetic field response sensor, a geometrically fixed capacitor mounting frame, a wireless dipstick, and an elastically flexible capacitor support have been developed. Either the capacitor mounting frame or the flexible, erectable magnetic field response sensor can be developed to take measurements in hazardous conditions, or in containers with environmentally harmful contents, such as a gasoline storage tank.

Posted in: Physical Sciences, Sensors, Briefs, TSP

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Multi-Step DRIE Process to Fabricate Silicon-Based THz Components

Commercial applications include airport screening systems, explosives detectors, nondestructive testing, and wireless communications. NASA’s Jet Propulsion Laboratory, Pasadena, California Terahertz (THz) frequency radiometers, spectrometers, and radars are promising instruments for the remote sensing of planetary atmospheres such as Mars, Venus, Jupiter, and Saturn, and their moons such as Titan, Europa, Ganymede, and others. For these long-term planetary missions, severe constraints are put on the mass and power budget for the payload instruments.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Flexible, Lightweight Vacuum Shell for Load-Responsive Multilayer Insulation for High Thermal Performance

There are substantial reductions in weight and improvements in performance. Goddard Space Flight Center, Greenbelt, Maryland Better thermal insulation is needed to insulate cryogenic propellants used by NASA for launch vehicles, spacecraft, and orbiting fuel depots. In particular, cryotank insulation during in-air pre-launch and launch ascent stages currently uses spray-on foam insulation (SOFI), which is extremely problematic.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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PICA-on-Edge

This material fills gaps between adjacent PICA blocks. Langley Research Center, Hampton, Virginia The current baseline ablator material for the Advanced Development Program (ADP) for the thermal protection system (TPS) of the Orion heat shield is phenolic impregnated carbon ablator (PICA). PICA is a low-density, low-strength material that must be isolated from mechanically and thermally induced deformations and strains of the underlying heat shield carrier structure. The current invention is being developed to provide a means of eliminating gaps between adjacent PICA blocks by filling the gaps with a compatible, relatively soft material that alleviates thermal and mechanical stresses that would occur in rigidly bonded PICA blocks. An ideal gap material should have comparable thermal and ablative performance to PICA, and have low enough porosity to prevent hot gas flow in the gap. It must be compliant enough that adjacent PICA blocks can move somewhat independently of each other and the underlying carrier structure to reduce thermal and mechanical stresses to acceptable levels.

Posted in: Materials, Briefs, TSP

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White, Electrically Dissipative Thermal Control Coating

Goddard Space Flight Center, Greenbelt, Maryland A highly reflective, white conductive coating system was developed using various layered coatings to maximize the structural, electrical, and optical reflectance properties for spacecraft radiators. The top layer of the system contains a highly reflective white pigment within a dissipative inorganic binder. This layer is above a highly conductive second layer containing a white conductive pigment within the same binder system.

Posted in: Materials, Briefs, TSP

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