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  • 1
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    Space particle imaging measurement system (SPIMS) (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: SPIMS is capable of detection and sizing of particles passing through a detection zone that is outside the detection system hardware. The particle detection is accomplished through the digital measurement of the shadow width of a laser source. The system is engineered as a space experiment, as a result of which the design is fully automated, solar blind, employs a robust digital detection scheme, is small and lightweight, and uses minimal power.
    Keywords: SPACECRAFT INSTRUMENTATION
    Type: In: Optical system contamination: Effects, measurement, control III; Proceedings of the Meeting, San Diego, CA, July 23, 24, 1992 (A93-32476 12-19); p. 86-93.
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  • 2
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    A Simplified Pattern Match Algorithm for Star Identification (1996)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A true pattern matching star algorithm similar in concept to the Van Bezooijen algorithm is implemented using an iterative approach. This approach allows for a more compact and simple implementation which can be easily adapted to be either an all-sky, no a priori algorithm or a follow on to a direct match algorithm to distinguish between ambiguous matches. Some simple analysis is shown to indicate the likelihood of mis-identifications. The performance of the algorithm for the all-sky, no a priori situation is detailed assuming he SKYMAP star catalog describes the true sky. The impact of errors and omissions in the SKYMAP catalog on performance are investigated. In addition, differing levels of noise in the star observations are assumed and results shown. The implications for possible implementation on-board spacecraft are discussed.
    Keywords: Astronomy
    Type: Flight Mechanics/Estimation Theory Symposium 1996; 3-14; NASA-CP-3333
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  • 3
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    Experience from the in-flight calibration of the Extreme Ultraviolet Explorer (EUVE) and Upper Atmosphere Research Satellite (UARS) fixed head star trackers (FHSTs) (1995)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Since the original post-launch calibration of the FHSTs (Fixed Head Star Trackers) on EUVE (Extreme Ultraviolet Explorer) and UARS (Upper Atmosphere Research Satellite), the Flight Dynamics task has continued to analyze the FHST performance. The algorithm used for inflight alignment of spacecraft sensors is described and the equations for the errors in the relative alignment for the simple 2 star tracker case are shown. Simulated data and real data are used to compute the covariance of the relative alignment errors. Several methods for correcting the alignment are compared and results analyzed. The specific problems seen on orbit with UARS and EUVE are then discussed. UARS has experienced anomalous tracker performance on an FHST resulting in continuous variation in apparent tracker alignment. On EUVE, the FHST residuals from the attitude determination algorithm showed a dependence on the direction of roll during survey mode. This dependence is traced back to time tagging errors and the original post launch alignment is found to be in error due to the impact of the time tagging errors on the alignment algorithm. The methods used by the FDF (Flight Dynamics Facility) to correct for these problems is described.
    Keywords: ASTRODYNAMICS
    Type: Flight Mechanics(Estimation Theory Symposium 1995; p 185-199
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  • 4
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    Frequency Analyzed Laser Light Scattering (Falls) (2002)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: A simple and robust light scattering technique for spray diagnostics was developed. The technique provides a spray's intact length and breakup frequency. Scattered light is collected from a laser sheet that illuminates a portion of the spray. The scattered light is imaged on a fast photodiode whose output is sampled at 20 kHz. Fast Fourier transform (FFT) analysis is performed on the sampled signal. The shape of the FFT produced can be correlated to one of three distinct spray regimes: intact sheet, ligaments, or droplets. Strobe and laser illuminated photographs are also shown for reference.
    Keywords: Lasers and Masers
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  • 5
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    Extreme Ultraviolet Explorer attitude determination support with a multimission three-axis stabilized spacecraft flight dynamics support system (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: The Extreme Ultraviolet Explorer (EUVE) was launched June 7, 1992 by an expendable Delta 2 launch vehicle. The Flight Dynamics Facility (FDF) at NASA Goddard Space Flight Center used a multimission three-axis stabilized spacecraft (MTASS) Flight Dynamics Support System (FDSS) to support the EUVE launch and mission operations. For EUVE, MTASS has been used to monitor attitude sensor performance, study OBC attitude determination performance, and study attitude perturbations. The current status of these efforts are summarized. After its successful implementation for EUVE, the Upper Atmosphere Research Satellite (UARS), and the Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX), MTASS has demonstrated multimission flight dynamics support systems can effectively bridge the gap between single-mission support systems of the past and future generic systems.
    Keywords: LAUNCH VEHICLES AND SPACE VEHICLES
    Type: In: Spaceflight dynamics 1993; AAS(NASA International Symposium, 8th, Greenbelt, MD, Apr. 26-30, 1993, Parts 1 & 2 . A95-85716 (ISSN 0065-3438); p. 763-777
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  • 6
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    A gyroscope calibration analysis for the Gamma Ray Observatory (GRO) (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Current documentation and software do not adequately address the calculation and use of the optimal weight matrices involved in calibrating inertial reference units (IRU). Several facets of the GRO IRU calibration as it relates to the bias and misalignment weighting matrices are investigated. The physical meaning and use of the bias and misalignment weight matrices in IRU calibration are examined. The relation of the weighting and the final biases, misalignments, and their corrections are pursued. Methods for determining reliable, realistic weighting matrices to be used in the GRO IRU calibration (IRUCAL) utility are determined. Possible correlations among observation uncertainties are also explored. For the undetermined case where the maneuvers are insufficient to identify all calibration parameters, the weighting matrices allow as much information as possible to be extracted from the measurements. Finally, applicable simulated flight data are used, incorporating the appropriate calibration maneuvers, to test the weighting matrices in the IRUCAL utility, and examine correlation effects.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flight Mechanics(Estimation Theory Symposium, 1989; p 237-253
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  • 7
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    Progress In Plasma Accelerator Development for Dynamic Formation of Plasma Liners (2002)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: An experimental plasma accelerator for magnetic target fusion (MTF) applications under development at the NASA Marshall Space Flight Center is described. The accelerator is a coaxial pulsed plasma thruster (Figure 1). It has been tested experimentally and plasma jet velocities of approx.50 km/sec have been obtained. The plasma jet has been photographed with 10-ns exposure times to reveal a stable and repeatable plasma structure (Figure 2). Data for velocity profile information has been obtained using light pipes and magnetic probes embedded in the gun walls to record the plasma and current transit respectively at various barrel locations. Preliminary spatially resolved spectral data and magnetic field probe data are also presented. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter is being characterized and future work for second generation "ultra-low jitter" gun development is being identified.
    Keywords: Plasma Physics
    Type: American Nuclear Society (ANS) Meeting; Jun 09, 2002 - Jun 13, 2002; Hollywood, FL; United States
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  • 8
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    Interfacial Stability of Spherically Converging Plasma Jets for Magnetized Target Fusion (2000)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: A fusion propulsion scheme has been proposed that makes use of the merging of a spherical distribution of plasma jets to dynamically form a gaseous liner to implode a magnetized target to produce the fusion reaction. In this paper, a study is made of the interfacial stability of the interaction of these jets. Specifically, the Orr-Sommerfeld equation is integrated to obtain the growth rate of a perturbation to the primary flow at the interface between the colliding jets. The results lead to an estimate on the tolerances on the relative flow velocities of the merging plasma jets to form a stable, imploding liner. The results show that the maximum temporal growth rate of the perturbed flow at the jet interface is very small in comparison with the time to full compression of the liner. These data suggest that, as far as the stability of the interface between the merging jets is concerned, the formation of the gaseous liner can withstand velocity variation of the order of 10% between the neighboring jets over the density and temperature ranges investigated.
    Keywords: Plasma Physics
    Type: Plasma Physics; Oct 23, 2000 - Oct 27, 2000; Quebec; Canada
    Format: text
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  • 9
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    WTEC panel report on research submersibles and undersea technologies (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This report covers research submersibles and related subsea technologies in Finland, France, Russia, Ukraine and the United Kingdom. Manned, teleoperated, and autonomous submersibles were of interest. The panel found that, in contrast to the United States, Europe is making substantial progress in cooperative and coordinated research in subsea technology, including the development of standards. France is a leader in autonomous vehicle technology. Because much less was known a priori about the technologies in Russia and Ukraine, there were more new findings in those countries than in those Western European nations visited. However, Russia and Ukraine have a sizeable (and currently underutilized) infrastructure in this field, including a highly educated and experienced manpower pool, impressive (in some cases unique) facilities for physical testing, extensive fleets of seagoing research vessels capable of long voyages, and state-of-the-art facilities for conducting oceanographic investigations. The panel visited newly-formed commercial companies associated with long-standing submersible R&D and production centers in Russia and Ukraine. So far, these new efforts are undercapitalized, and as such represent opportunities at very low cost for Western nations, as detailed in the site reports.
    Keywords: ENGINEERING (GENERAL)
    Type: NASA-CR-198565 , NAS 1.26:198565 , PB94-184843
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  • 10
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    Magnetic and Langmuir Probe Measurements on the Plasmoid Thruster Experiment (PTX) (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Plasmoid Thruster Experiment (PTX) operates by inductively producing plasmoids in a conical theta-pinch coil and ejecting them at high velocity. A plasmoid is a plasma with an imbedded closed magnetic field structure. The shape and magnetic field structure of the translating plasmoids have been measured with of an array of magnetic field probes. Six sets of two B-dot probes were constructed for measuring B(sub z) and B(sub theta), the axial and azimuthal components of the magnetic field. The probes are wound on a square G10 form, and have an average (calibrated) NA of 9.37 x l0(exp -5) square meters, where N is the number of turns and A is the cross-sectional area. The probes were calibrated with a Helmholtz coil, driven by a high-voltage pulser to measure NA, and by a signal generator to determine the probe's frequency response. The plasmoid electron number density n(sub e) electron temperature T(sub e), and velocity ratio v/c(sub m), (where v is the bulk plasma flow velocity and c(sub m), is the ion thermal speed) have also been measured with a quadruple Langmuir probe. The Langmuir probe tips are 10 mm long, 20-mil diameter stainless steel wire, housed in a 6-inch long 4-bore aluminum rod. Measurements on PTX with argon and hydrogen from the magnetic field probes and quadruple Langmuir probe will be presented in this paper.
    Keywords: Electronics and Electrical Engineering
    Type: Joint Propulsion Conference; Jul 11, 2004 - Jul 14, 2004; Fort Lauderdale, FL; United States
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