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Featured researches published by H. H. Plotkin.


Science | 1973

The Lunar Laser Ranging Experiment: Accurate ranges have given a large improvement in the lunar orbit and new selenophysical information

P. L. Bender; Douglas G. Currie; S. K. Poultney; C. O. Alley; R. H. Dicke; D. T. Wilkinson; D. H. Eckhardt; J. E. Faller; William M. Kaula; J. D. Mulholland; H. H. Plotkin; E. C. Silverberg; James G. Williams

The lunar ranging measurements now being made at the McDonald Observatory have an accuracy of 1 nsec in round-trip travel time. This corresponds to 15 cm in the one-way distance. The use of lasers with pulse-lengths of less than 1 nsec is expected to give an accuracy of 2 to 3 cm in the next few years. A new station is under construction in Hawaii, and additional stations in other countries are either in operation or under development. It is hoped that these stations will form the basis for a worldwide network to determine polar motion and earth rotation on a regular basis, and will assist in providing information about movement of the tectonic plates making up the earths surface. Several mobile lunar ranging stations with telescopes having diameters of 1.0 m or less could, in the future, greatly extend the information obtainable about motions within and between the tectonic plates. The data obtained so far by the McDonald Observatory have been used to generate a new lunar ephemeris based on direct numerical integration of the equations of motion for the moon and planets. With this ephemeris, the range to the three Apollo retro-reflectors can be fit to an accuracy of 5 m by adjusting the differences in moments of inertia of the moon about its principal axes, the selenocentric coordinates of the reflectors, and the McDonald longitude. The accuracy of fitting the results is limited currently by errors of the order of an arc second in the angular orientation of the moon, as derived from the best available theory of how the moon rotates in response to the torques acting on it. Both a new calculation of the moons orientation as a function of time based on direct numerical integration of the torque equations and a new analytic theory of the moons orientation are expected to be available soon, and to improve considerably the accuracy of fitting the data. The accuracy already achieved routinely in lunar laser ranging represents a hundredfold improvement over any previously available knowledge of the distance to points on the lunar surface. Already, extremely complex structure has been observed in the lunar rotation and significant improvement has been achieved in our knowledge of lunar orbit. The selenocentric coordinates of the retroreflectors give improved reference points for use in lunar mapping, and new information on the lunar mass distribution has been obtained. Beyond the applications discussed in this article, however, the history of science shows many cases of previously unknown, phenomena discovered as a consequence of major improvements in the accuracy of measurements. It will be interesting to see whether this once again proves the case as we acquire an extended series of lunar distance observations with decimetric and then centimetric accuracy.


Science | 1972

Polar Motion from Laser Tracking of Artificial Satellites

David E. Smith; R. Kolenkiewicz; Peter J. Dunn; H. H. Plotkin; Tom Johnson

Measurements of the range to the Beacon Explorer C spacecraft from a single laser tracking system at Goddard Space Flight Center have been used to determine the change in latitude of the station arising from polar motion. A precision of 0.03 arc second was obtained for the latitude during a 5-month period in 1970.


IEEE Journal of Quantum Electronics | 1967

2.5a - A laser satellite ranging system - Part I: Equipment description

Tom Johnson; H. H. Plotkin; P. Spadin

A laser tracking system has been used to track three satellites equipped with retroreflectors. An rms scatter of one to two meters derived from 200-200 observations per pass agrees with the expected instrumental precision.


Optics Letters | 2000

Remote detection of Raman scattering by use of a holographic optical element as a dispersive telescope

T. A. Berkoff; David N. Whiteman; R. D. Rallison; Geary K. Schwemmer; L. Ramos-Izquierdo; H. H. Plotkin

We describe the retrieval of nighttime lidar profiles by use of a large holographic optical element to simultaneously collect and spectrally disperse Raman-shifted return signals. Results obtained with a 20-Hz, 6-mJ/pulse , frequency-tripled Nd:YAG source demonstrate profiles for atmospheric nitrogen with a range greater than 1 km for a time average of 26 s.


international geoscience and remote sensing symposium | 1991

National Aeronautics And Space Administration's Research Program In Earth Remote Sensing Instrumentation

H. H. Plotkin; Martin M. Sokoloski; Bernard Rubin

Terrestrial and atmospheric missions of NASAs program to develop remote sensing instrumentation are described along with several of the instruments and related mission. Systems such as lidar and radar, passive coherent sensors, passive noncoherent sensors, as well as cryogenic cooler technology are discussed.


Physical Review Letters | 1976

New test of the equivalence principle from lunar laser ranging

J. G. Williams; R. H. Dicke; P. L. Bender; C. O. Alley; Walter Carter; Douglas G. Currie; D. H. Eckhardt; J. E. Faller; William M. Kaula; J. D. Mulholland; H. H. Plotkin; S. K. Poultney; P. J. Shellus; E. C. Silverberg; W. Sinclair; M. Slade; D. T. Wilkinson


Archive | 1974

Laser technology for high precision satellite tracking

H. H. Plotkin


Journal of Geophysical Research | 1965

Optical radar using a corner reflector on the Moon

C. O. Alley; P. L. Bender; R. H. Dicke; J. E. Faller; P. A. Franken; H. H. Plotkin; D. T. Wilkinson


Science | 1970

Apollo 11 Laser Ranging Retro-Reflector: Initial Measurements from the McDonald Observatory

C. O. Alley; R. F. Chang; D. G. Curri; J. Mullendore; S. K. Poultney; J. D. Rayner; E. C. Silverberg; C. A. Steggerda; H. H. Plotkin; W. Williams; Brian Warner; H. Richardson; B. Bopp


Applied Optics | 2001

Performance modeling of an airborne Raman water-vapor lidar

Whiteman Dn; Geary K. Schwemmer; Timothy A. Berkoff; H. H. Plotkin; Luis Ramos-Izquierdo; Gelsomina Pappalardo

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P. L. Bender

University of Colorado Boulder

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J. D. Mulholland

California Institute of Technology

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J. E. Faller

University of Colorado Boulder

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E. C. Silverberg

University of Texas at Austin

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Tom Johnson

Goddard Space Flight Center

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Geary K. Schwemmer

Goddard Space Flight Center

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