Tech Briefs

Exciting and Detecting Electromagnetic Energy in a High-Temperature Microwave Cavity

This weak-coupling approach can be used by industry for temperature-dependent dielectric measurements of high-value materials. NASA’s Jet Propulsion Laboratory, Pasadena, California There is a need to perform accurate, high-temperature, complex dielectric constant measurements at microwave frequencies on materials, such as those on the surface of Venus (surface temperature 460 °C). One approach is to excite and detect a TE10n mode resonance in a waveguide cavity heated in a high-temperature furnace. The standard way is to use commercial high-temperature transition adapters attached to cavity end plates containing small iris holes that weakly couple microwave energy into and out of the cavity. These high-temperature transition adapters are not simple to make, and are rather large in size. The addition of the transition adapter units to the waveguide cavity leads to a long combined system that in many cases makes it difficult, if not impossible, to insert in conventional high-temperature furnaces.

Posted in: Physical Sciences, Briefs, TSP

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Hollow aErothermal Ablation and Temperature (HEAT) Sensor for Tracking Isotherm Through TPS Material

This sensor can “see” through insulation. Ames Research Center, Moffett Field, California The Hollow aErothermal Ablation and Temperature (HEAT) sensor is a multifunction sensor designed to track an isotherm by making an independent transient measurement at a defined location in the sensor that is equal to the temperature at which its constituent materials char. By this same operating principle, the HEAT sensor tracks the transient char depth progression within a thermal protection system (TPS) material. In the case of a material that sublimes (such as Teflon), or when the aerothermal environment induces steady-state ablation, the HEAT sensor measures material ablation directly.

Posted in: Physical Sciences, Briefs, TSP

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Hydrogen Measurement in a Cryogen Flow Stream Reduces Waste of Helium

Energy conservation and sustainability technologies are applied for propellant conservation. Stennis Space Center, Mississippi The purpose of this research was to develop an improved method for measuring hydrogen concentrations in a cryogen flow stream to minimize helium waste during the purge process. Currently, this type of measurement is performed manually with a sniffer, and involves obtaining periodic measurements that are not accurate or repeatable and do not optimize the conservation of hydrogen. The goal of this project was to create an autonomous real-time method for continuously measuring hydrogen that potentially offers not only cost saving advantages by conserving expensive resources that are used for purging, but also for providing an additional safety mechanism to monitor hydrogen in a cryogenic flow stream.

Posted in: Physical Sciences, Briefs

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Noncontact DC and AC Magnetostrictive Current Sensor

John H. Glenn Research Center, Cleveland, Ohio At the time of this reporting, there have been no effective methods of monitoring current in conductors in space without breaking the circuit or making contact with the conductor. In space, reliability rules all designs, and breaking a circuit to insert a sensor to monitor current would reduce reliability of the system. Hall effect sensors provide a noncontact DC measurement technique, but they are relatively expensive and not rugged enough for the space environment.

Posted in: Physical Sciences, Briefs

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Method and Apparatus for Determining Propellant Mass in Microgravity by Capacitance Measurements

The method is relatively insensitive to propellant orientation. Marshall Space Flight Center, Alabama Propellant mass gauging in microgravity has posed a challenge for decades. Various methods have been applied, including ultrasonic, capacitance probes, point level sensors, thermal detectors (thermistors, thermocouples, etc.), Michelson interferometry, and nuclear devices. All have problems in terms of how to provide accurate measurements irrespective of the fluid orientation in the tank.

Posted in: Physical Sciences, Briefs

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Computer Modeling for Generation of Synthetic Radio Reflection-Transmission Tomography (RRTT) Data

Goddard Space Flight Center, Greenbelt, Maryland Numerical algorithms capable of generating synthetic radio tomography data (reflection transmission data) for asteroids, comets, and other near-Earth orbits (NEOs) were developed. Future missions to main asteroid belt objects, NEOs, and other small bodies of the solar system will aim to investigate the surface and subsurface compositions and internal structure of these objects with help of an onboard, low-frequency radio sounder. The resulting numerical model thus developed will be useful in performing trade studies required for designing an optimum radio sounder for the future missions. The forward numerical model will also be important for estimating structural properties of the small objects from the data collected by these future missions.

Posted in: Information Sciences, Electronics & Computers, Briefs, TSP

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Designing Planning Information for Automation into PRL

Lyndon B. Johnson Space Center, Houston, Texas Automation and autonomy are key elements in realizing the vision for space exploration. The NASA Exploration Technology Development Program (ETDP) has been developing several core autonomy capabilities, one of which is called a procedure representation language (PRL). PRL can be automatically translated into code that can be executed by NASA-developed autonomous executives.

Posted in: Information Sciences, Electronics & Computers, Briefs, TSP

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