Methods of Orbit Refinement

Blackman, R. B.

doi:10.1002/j.1538-7305.1964.tb01011.x

Cited by 20 publications

(2 citation statements)

References 7 publications

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“…In the better-observed cases of the 19 January and 11 February events, this additional analysis allows us to uniquely identify the near or far radiant as the source location of the ejection events. This process starts by performing an initial OD for each observed particle using a traditional "angles-only" technique (69). In this technique, image data are converted from pixel-line coordinates to right ascension and declination from the spacecraft in the inertial reference frame.…”

Section: Ejection Event Orbit Determinationmentioning

confidence: 99%

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu

Лауретта

Hergenrother

Chesley

et al. 2019

Science

152

187

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Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts.

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Section: Ejection Event Orbit Determinationmentioning

confidence: 99%

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu

Лауретта

Hergenrother

Chesley

et al. 2019

Science

152

187

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“…Radar techniques for observing celestial bodies are well established, including enhancement of resolving power by simultaneous resolutions of Doppler frequencies and range. The determination of orbital parameters is highly refined [Blackman, 1964].…”

Section: Communication Theory Modulation Theory Etcmentioning

confidence: 99%

U.S.A. National Assembly, Committee Report, Fifteenth URSI General Munich, September 1966: Commission 6, Radio Waves and Transmission OF Information; Progress. in Radio Waves and Transmission of

Darlington¹,

Felsen²,

Siegel³

et al. 1966

Radio Science

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Many important papers have appeared; only a few can be given here. In cylindrical antenna theory, accurate current and field distributions were found for isolated [King and Wu, 1965] and coupled [King and Sandler, 1964] elements. A fine summary of broadband antennas by Jordan was referenced in recent studies of log‐spiral antennas [Dyson, 1965]. New structures included the wire‐grid HF Luneburg lens [Sharp, 1965] and double‐helix antennas [Ehrenspeck, 1965]. Advances in large quasi‐optical antennas included an analysis of focal fields and line source feeds for spherical reflectors [Schell, 1963]; analysis of reflector‐subreflector systems such as Cassegrain and Gregorian types [Morgan, 1964]; and a book treating aperture antennas and including many references [Hansen, 1964]. Progress in optical scanning systems included geodesic Luneburg lenses [Ruddock, Ryan, and Walter, 1964], bootlace lenses [Kales and Brown 1965], and parallel‐plate scanners [Rotman and Turner, 1963]. Electronic scanning of phased arrays received major attention. Mutual impedance changes With scan angles were analyzed by the impedance crater concept [Rhodes, 1964]; also techniques for compensating for these changes were developed [Hannan, Lerner, and Knittel, 1965). Important progress has been made in digital phase shifters. The diode type [White, 1965] has recently been supplemented by latching types employing ferrite cores [Whicker and Jones, 1965]. Adaptive array systems were covered in a special issue [IEEE, 1964]; of particular interest are the Gruenberg paper on retrodirective systems and the Skolnik and King paper on selfsteering arrays. The annular slot array has been developed for monopulse [Kelly and Goebels, 1964]. Nonuniformly spaced array sidelobes have been bounded by a probabilistic approach [Lo, 1964]. Finally, the important but long unsolved problem of an optimum directivity source with supergain ratio constraint was formally solved [Rhodes, 1963].

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On Systematic Errors in Trajectory Determination Problems

Claus¹

1966

Peaceful Uses of Automation in Outer Space

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Methods of Orbit Refinement

Cited by 20 publications

References 7 publications

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu

U.S.A. National Assembly, Committee Report, Fifteenth URSI General Munich, September 1966: Commission 6, Radio Waves and Transmission OF Information; Progress. in Radio Waves and Transmission of

On Systematic Errors in Trajectory Determination Problems

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