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  • 1
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    Unknown
    In:  CASI
    Publication Date: 2006-06-13
    Description: When using DSS 14 in a monostatic configuration, radar observations of Titan show that Titan is a diffuse reflector with a relative radar cross section of 0.14+/-0.03. No hot spots were observed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: The Telecommunications and Data Acquisition Report; p 377-379
    Format: text
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  • 2
    Publication Date: 2011-08-19
    Description: A new method of measuring surface currents using an interferometric synthetic aperture radar is presented. An airborne implementation has been tested over San Francisco Bay near the time of maximum tidal flow, resulting in a map of the east-west component of the current. Only the line-of-sight component of velocity is measured by this technique. Where the SNR ratio was strongest, statistical fluctuations of less than 4 cm/s were observed for ocean patches of 60 x 60 m.
    Keywords: OCEANOGRAPHY
    Type: Nature (ISSN 0028-0836); 328; 707-709
    Format: text
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  • 3
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    Unknown
    In:  Other Sources
    Publication Date: 2011-08-19
    Description: A method of remotely measuring near-surface ocean currents with a synthetic aperture radar (SAR) is described. The apparatus consists of a single SAR transmitter and two receiving antennas. The phase difference between SAR image scenes obtained from the antennas forms an interferogram that is directly proportional to the surface current. The first field test of this technique against conventional measurements gives estimates of mean currents accurate to order 20 percent, that is, root-mean-square errors of 5 to 10 centimeters per second in mean flows of 27 to 56 centimeters per second. If the full potential of the method could be realized with spacecraft, then it might be possible to routinely monitor the surface currents of the world's oceans.
    Keywords: OCEANOGRAPHY
    Type: Science (ISSN 0036-8075); 246; 1282-128
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  • 4
    Publication Date: 2013-08-31
    Description: The advent of interferometric synthetic aperture radar (INSAR) imagery brought to the ocean remote sensing field techniques used in radio astronomy. Whilst details of the interferometry differ between the two fields, the basic idea is the same: Use the phase information arising from positional differences of the radar receivers and/or transmitters to probe remote structures. The interferometric image is formed from two complex synthetic aperture radar (SAR) images. These two images are of the same area but separated in time. Typically the time between these images is very short -- approximately 50 msec for the L-band AIRSAR (Airborne SAR). During this short period the radar scatterers on the ocean surface do not have time to significantly decorrelate. Hence the two SAR images will have the same amplitude, since both obtain the radar backscatter from essentially the same object. Although the ocean surface structure does not significantly decorrelate in 50 msec, surface features do have time to move. It is precisely the translation of scattering features across the ocean surface which gives rise to phase differences between the two SAR images. This phase difference is directly proportional to the range velocity of surface scatterers. The constant of proportionality is dependent upon the interferometric mode of operation.
    Keywords: OCEANOGRAPHY
    Type: Summaries of the 4th Annual JPL Airborne Geoscience Workshop. Volume 3: AIRSAR Workshop; p 1-
    Format: application/pdf
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  • 5
    Publication Date: 2011-08-19
    Description: Ocean surface waves can be clearly observed by SAR in the interferometric configuration (INSAR) due to the ability of INSAR to provide images of the local surface velocity field. It is shown here that INSAR can be used to obtain wavenumber spectra that are in agreement with power spectra measured in situ. This new method has considerable potential to provide instantaneous spatial information about the structure of ocean wave fields.
    Keywords: OCEANOGRAPHY
    Type: Nature (ISSN 0028-0836); 345; 793-795
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  • 6
    Publication Date: 2019-06-28
    Description: During the 1977 inferior conjunction of Venus, radar observations were made using three receiving stations as a multiple interferometer. Maps of surface reflectivity and altimetry were prepared from these observations. The new altimetry maps show considerable improvement in relation to many of the earlier maps made using the two-station interferometer. In particular, there are consistent and explainable correlations between the altimetry and reflectivity maps that did not always exist in the past. The highest-resolution maps (about 8 km) show three isolated mountains having altitudes of approximately 2 km above their environs, a pair of ridges separated by approximately 100 km and extending 800 km, and a few anomalous reflectivity features for which little or no altitude change is observed. Other maps at slightly lower resolution show a bright irregular ringed crater, a few large low-reflectivity regions, a shallow crater 150 km in diameter, a gently sloping mountain, and a short ridge running north-south. Many of the later features have been seen in earlier radar maps and should be useful in refining the spin axis and further characterizing the regolith of certain areas of Venus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Dec. 30
    Format: text
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  • 7
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    Unknown
    In:  Other Sources
    Publication Date: 2019-06-27
    Description: Radar observations of Ganymede at X band show that the surface is unusually bright and has unusual polarization properties. A model of the surface based on large numbers of random ice facets (hence vacuum-ice interfaces) is able to account for these characteristics.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 207; Jan. 11
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  • 8
    Publication Date: 2019-06-27
    Description: Two radar observations of a set of three relatively small features on the surface of Venus have facilitated a refined determination of the spin vector of Venus. The period is found to be 243.019 + or 0.014 days, while the obliquity is 177.22 + or - 0.18 deg. The effects of deviations from exact sphericity on the interpretation of the measurements are discussed at length and the question of resonance with earth is reexamined.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal; 85; Aug. 198
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  • 9
    Publication Date: 2019-06-28
    Description: Delay-Doppler observations at 12.6 cm which have been used to estimate the relative radar reflectivities of Saturn's classical ring sections show that the A and B rings are responsible for most of the radar echo, and that the average radar reflectivity per unit of projected area of the A ring is 90% as large as the B ring. No firm evidence is found for radar backscattering from particles interior to the B ring, exterior to the A ring, of from the planet itself. Unexpectedly large amounts of power at Doppler shifts near the center of the echo spectrum, which had been reported at 3.5 and 12.6 cm for ring plane tilt angles greater than 24.4 deg are not apparent in spectra for those wavelengths obtained at ring plane tilt angles smaller than 21.4 deg.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 49; Mar. 198
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  • 10
    Publication Date: 2019-06-27
    Description: Seven radar-brightness and altitude images are presented. They are each of a small circular region within the equatorial belt of Venus. Resolution is, typically, 10 by 10 km; altitude contour spacing is 500 m. In addition, an image of the large rough feature, beta, is presented with 25 by 25 km resolution.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 36; Dec. 197
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