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  • 1
    Publication Date: 2013-08-31
    Description: With increasing flight duration and the possibility of a permanent facility in space, long-term monitoring of material degradation due to atomic oxygen is increasing in importance. Reliance on models to determine the fluence of atomic oxygen is not only necessarily complex but also imprecise due to the strong dependence of oxygen concentration on day/night, latitude and solar activity. Mass-spectroscopy, the traditional method for determining the gas phase species densities at low pressure, is not only expensive but is limited in the area that it can monitor. Our group has developed a simple and inexpensive dosimeter to measure the atomic oxygen fluence via the change in resistance as the sensor element is gradually oxidized. The sensors consisted of thin-film circuit elements deposited on a suitable substrate. Four-point resistance measurements were used to monitor the change in resistance. Results obtained using silver and carbon dosimeters flown on STS-46 (CONCAP 2-01) will be discussed.
    Keywords: ATOMIC AND MOLECULAR PHYSICS
    Type: NASA. Langley Research Center, LDEF: 69 Months in Space. Third Post-Retrieval Symposium, Part 3; p 957-970
    Format: application/pdf
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  • 2
    Publication Date: 2018-06-02
    Description: Active phased array antennas with electronically scanned beams offer advantages over high gain parabolic dish antennas currently used on spacecraft. Benefits include the elimination of deployable structures, no moving parts, and no torque disturbances that moving antennas impart to the spacecraft. The latter results in the conservation of spacecraft power, and the ability to take precision optical data while transmitting data. Such an antenna has been built under a contract from NASA Goddard Space Flight Center for the New Millennium Program EO- 1 satellite where it will act as the primary highspeed scientific data communication link. The antenna operates at X-band, has an integral controller and power conditioner, communicates with the spacecraft over a 1773 optical data bus, and is space qualified for low earth orbit (705 Km altitude). The nominal mission length is one year, and the operational requirement is for one 10 minute transmission a day over Spitsbergen, Norway. Details of the antenna and its performance will be described in the following paper.
    Keywords: Communications and Radar
    Type: IEEE Antennas and Propagation Society International Symposium, Volume 1; 150-153; IEEE-Catalog-99CH37010-Vol-1
    Format: text
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  • 3
    Publication Date: 2019-06-28
    Description: The emission spectrum of NO from several rotational levels in the first excited state has been recorded. Branching ratios have been measured and Franck-Condon Factors calculated from the experimental data. Lifetimes of the lines used have been measured and Einstein A-values calculated.
    Keywords: ATOMIC AND MOLECULAR PHYSICS
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer (ISSN 0022-4073); 29; April 19
    Format: text
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  • 4
    Publication Date: 2019-06-27
    Description: The partitioning of excess photochemical energy as a function of the vibrational energy of the state of C2N2 has been measured. Surprisal theory has been used to analyze the data and it shows that complete randomization does not occur before dissociation. The results are also inconsistent with the predictions of the quasidiatomic theory for photodissociation.
    Keywords: ATOMIC AND MOLECULAR PHYSICS
    Type: Journal of Chemical Physics; 71; Dec. 1
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  • 5
    Publication Date: 2019-07-12
    Description: Lifetimes and self-quenching rates have been measured for excited states of Xe I that were populated using simultaneous two-photon absorption. Lifetimes measured in this study are somewhat shorter than those measured using the broadband-excitation technique. Lifetimes reported here are all faster than 100 nsec. Deactivation rates are approximately 2 x 10 to the -10th cu cm/sec per mol.
    Keywords: ATOMIC AND MOLECULAR PHYSICS
    Type: Optical Society of America, Journal, B: Optical Physics (ISSN 0740-3224); 2; 414-416
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  • 6
    Publication Date: 2019-07-13
    Description: A mobile, rapidly deployable ground-based system to track and image targets of aeronautical interest has been developed. Targets include reentering reusable launch vehicles (RLVs) as well as atmospheric and transatmospheric vehicles. The optics were designed to image targets in the visible and infrared wavelengths. To minimize acquisition cost and development time, the system uses commercially available hardware and software where possible. The conception and initial funding of this system originated with a study of ground-based imaging of global aerothermal characteristics of RLV configurations. During that study NASA teamed with the Missile Defense Agency/Innovative Science and Technology Experimentation Facility (MDA/ISTEF) to test techniques and analysis on two Space Shuttle flights.
    Keywords: Communications and Radar
    Type: 11th International Symposium on Flow Visualization; Aug 09, 2004 - Aug 12, 2004; Notre Dame, IN; United States
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