Physical Sciences

Digital Laser Frequency Stabilization via Cavity Locking Employing Low-Frequency Direct Modulation

Direct modulation reduces complexity, volume, and mass. NASA’s Jet Propulsion Laboratory, Pasadena, California This project’s goal was to simplify laser frequency stabilization. A simpler system will have many benefits, including reduction of power consumption, complexity, volume, mass, and risk of failure. To implement the Pound-Drever-Hall (PDH) technique requires both RF modulation and demodulation electronics, including an electro-optic modulator, a photoreceiver of sufficient bandwidth to detect the RF modulation fields, demodulation electronics of sufficient bandwidth, and an RF function generator. For a space mission, this equipment can be costly and power-hungry, in addition to the difficulty of being rated to operate in the harsh space environment.

Posted in: Briefs, TSP

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Deep UV Discharge Lamps in Capillary Quartz Tubes with Light Output Coupled to an Optical Fiber

NASA’s Jet Propulsion Laboratory, Pasadena, California Researchers at Jet Propulsion Laboratory have come up with a novel approach to the simplification of the 194-nm light source and optical guidance in mercury trapped ion spectroscopy research. Mercury plasma is generated in a capillary tube with a diameter of a few hundred microns (in contrast to current lamp bulbs with a diameter of 13 mm). The deep ultraviolet (DUV) light from the plasma can be guided directly to the ions held in an ion trap in a vacuum system via a piece of DUV fiber that is fused at the end of the capillary tube.

Posted in: Briefs

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Speech Acquisition and Automatic Speech Recognition for Integrated Spacesuit Audio Systems, Version II

System offers superior performance from prior version, and a number of commercial applications. John H. Glenn Research Center, Cleveland, Ohio Astronauts suffer from poor dexterity of their hands due to the clumsy spacesuit gloves during Extravehicular Activity (EVA) operations, and NASA has had a widely recognized but unmet need for novel human-machine interface technologies to facilitate data entry, communications, and robots or intelligent systems control. A speech interface driven by an astronaut’s own voice is ideal for EVA operations, since speech is the most natural, flexible, efficient, and economical form of human communication and information exchange.

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Advanced Sensor Technology for Algal Biotechnology

Ames Research Center, Moffett Field, California Advanced Sensor Technology for Algal Biotechnology (ASTAB) is an integrated package of water quality and algal physiology sensors designed to enable algae growers to increase significantly productivity and efficiency of their operations, optimize harvesting periods, and avoid losses of “batches” of algae through nutrient deficiencies and/or population shifts. This sensor technology is expected to increase process automation and performance in large-scale algal production facilities.

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High-Speed Spectral Mapper

NASA’s Jet Propulsion Laboratory, Pasadena, California The Hyperspectral Infrared Imager (HyspIRI) spaceborne mission has two imaging sensors operating in the visible to shortwave infrared (VSWIR) and the thermal infrared (TIR), respectively. The HyspIRI-TIR imaging instrument is being developed for infrared mapping of the Earth in 8 spectral bands with a 5-day revisit time at the equator. The system will have 60-m ground resolution at nadir, 200-mK noise-equivalent temperature difference (NETD) for 300 K scenes, and 0.5 ºC absolute temperature accuracy. As the spacecraft moves in its polar orbit, a rotating scan mirror allows the telescope to view a 51º cross-track nadir strip, an internal blackbody target, and space, every 2.1 s. Combining the overlapping strips will yield a 51º (597-km) wide swath below the spacecraft.

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Optical Phased Array with Digitally Enhanced Interferometry

NASA’s Jet Propulsion Laboratory, Pasadena, California A proof-of-concept technique has been developed for measuring and controlling the individual phases of array elements. Electro-optic steering and beam-forming of laser beams is an emerging field with devices such as optical phased arrays that are capable of steering with significantly reduced noise floors and that are faster by orders of magnitude.

Posted in: Test & Measurement, Briefs, TSP

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Mass Spectrometry of Spacecraft Contamination Using the Direct Analysis in Real-Time Ion Source

NASA’s Jet Propulsion Laboratory, Pasadena, California Mass spectrometry is presented as a powerful tool for the analysis of spacecraft contamination when coupled to the Direct Analysis in Real Time (DART) ionization source. DART technology is based on soft ionization and desorption using metastable helium (MSHe). This provides efficient sample introduction for the rapid analysis of polymers and bio-organic compounds. It is particularly useful to the evaluation of polymers that may outgas in the space environment. In addition, this approach provides sensitive analysis of bio-marker and organic compounds that may interfere with organic and life detection instruments on future spacecraft missions.

Posted in: Test & Measurement, Briefs

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