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  • 1
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    Electrification of Experimental Volcanic Jets with Varying Water Content and Temperature (2021)
    Details
    Publication Date: 2021-10-12
    Description: Volcanic lightning—a near ubiquitous feature of explosive volcanic eruptions—possesses great potential for the analysis of volcanic plume dynamics. To date, the lack of quantitative knowledge on the relationships between plume characteristics hinders efficient data analysis and application of the resulting parameterizations. We use a shock-tube apparatus for rapid decompression experiments to produce particle-laden jets. We have systematically and independently varied the water content (0–27 wt%) and the temperature (25–320 °C) of the particle-gas mixture. The addition of a few weight percent of water is sufficient to reduce the observed electrification by an order of magnitude. With increasing temperature, a larger number of smaller discharges are observed, with the overall amount of electrification staying similar. Changes in jet dynamics are proposed as the cause of the temperature-dependence, while multiple factors (including the higher conductivity of wet ash) can be seen responsible for the decreased electrification in wet experiments.
    Keywords: 550.724 ; volcanic lightning ; atmospheric electricity ; Faraday cage ; volcanic jets ; temperature ; water content
    Language: English
    Type: map
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    CITATION GEO-LEO
  • 2
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    Path-constrained rendezvous - Necessary and sufficient conditions (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The problem of path-constrained rendezvous in the vicinity of a Large Space Structure (LSS) was first introduced some years ago. The present contribution to this field centers on a demonstration that the problem can be reduced from a path-constraint problem to one of end-point constraints or certain (common) LSS geometries, under the assumption of an unrestrictive upper limit on the transfer time. This finding has been made under the assumption of a circular Keplerian orbit, and has been normalized with respect to orbital semimajor axis and LSS size. In addition to demonstrating this important simplification of the path-constrained rendezvous problem, the results of numerical simulations of path-constrained transfers from point-to-point on large spherical structures in orbit are discussed, and a series of conclusions having both architectural (design) and operational implications for LSS designers/operators is derived.
    Keywords: ASTRODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 23; 492-498
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Inadequacy of single-impulse transfers for path constrained rendezvous (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The use of single-impulse techniques to maneuver from point to point about a large space structure (LSS) with an arbitrary geometrical configuration and spin is examined. Particular consideration is given to transfers with both endpoints on the forbidden zone surface. Clohessy-Wiltshire equations of relative motion are employed to solve path constrained rendezvous problems. External and internal transfers between arbitrary points are analyzed in terms of tangential departure and arrival conditions. It is observed that single-impulse techniques are inadequate for transferring about the exterior of any LSS; however, single-impulse transfers are applicable for transfers in the interior of LSSs. It is concluded that single-impulse transducers are not applicable for path constrained rendezvous guidance.
    Keywords: ASTRODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 24; 282-284
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Operational implications for path constrained rendezvous (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: After noting that many large orbiting space structures will be of such magnitude as to require proximity rendezvous guidance targeting in order to accomplish path-constrained approaches in the vicinity of their exterior surfaces, attention is given to the difficulties that inhere in the accomplishment of such rendezvous transfers due to physical constraints imposed by the structures' surfaces. Operationally feasible transfer techniques which circumvent the path constraints inherent in these maneuvers are discussed under the assumption of a number of restrictions. The techniques presented may be important in asteroid exploration and exploitation.
    Keywords: ASTRODYNAMICS
    Type: AIAA PAPER 85-1916 , Guidance, Navigation and Control Conference; Aug 19, 1985 - Aug 21, 1985; Snowmass, CO
    Format: text
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    NASA TECHNICAL REPORTS
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