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Smooth plains units attributed to fluidized basin ejecta occur over much of the lunar highlands. We examined 4–20 km diameter Imbrian- and Eratosthenian-period craters in the southern highlands that have high 12.6-cm wavelength radar backscatter and circular polarization ratios associated with their interior walls but not with their proximal ejecta. Of these craters, about 70% occur on or very near...
Over the last decade, observations acquired by the Shallow Radar (SHARAD) sounder on individual passes of the Mars Reconnaissance Orbiter have revealed the internal structure of the Martian polar caps and provided new insights into the formation of the icy layers within and their relationship to climate. However, a complete picture of the cap interiors has been hampered by interfering reflections...
Radar sounder studies of icy, sedimentary, and volcanic settings can be affected by reflections from surface topography surrounding the sensor nadir location. These off-nadir “clutter” returns appear at similar time delays to subsurface echoes and complicate geologic interpretation. Additionally, broadening of the radar echo in delay by surface returns sets a limit on the detectability of subsurface...
We combine Earth-based radar maps of Venus from the 1988 and 2012 inferior conjunctions, which had similar viewing geometries. Processing of both datasets with better image focusing and co-registration techniques, and summing over multiple looks, yields maps with 1–2km spatial resolution and improved signal to noise ratio, especially in the weaker same-sense circular (SC) polarization. The SC maps...
We present Earth-based radar images of Mars obtained with the upgraded Arecibo S-band (λ=12.6cm) radar during the 2005–2012 oppositions. The imaging was done using the same long-code delay-Doppler technique as for the earlier (pre-upgrade) imaging but at a much higher resolution (∼3km) and, for some regions, a more favorable sub-Earth latitude. This has enabled us to make a more detailed and complete...
We present results of a campaign to map much of the Moon’s near side using the 12.6-cm radar transmitter at Arecibo Observatory and receivers at the Green Bank Telescope. These data have a single-look spatial resolution of about 40m, with final maps averaged to an 80-m, four-look product to reduce image speckle. Focused processing is used to obtain this high spatial resolution over the entire region...
We map the subsurface structure of Planum Boreum using sounding data from the Shallow Radar (SHARAD) instrument onboard the Mars Reconnaissance Orbiter. Radar coverage throughout the 1,000,000-km 2 area reveals widespread reflections from basal and internal interfaces of the north polar layered deposits (NPLD). A dome-shaped zone of diffuse reflectivity up to 12μs (∼1-km thick) underlies two-thirds...
The SHARAD (shallow radar) sounding radar on the Mars Reconnaissance Orbiter detects subsurface reflections in the eastern and western parts of the Medusae Fossae Formation (MFF). The radar waves penetrate up to 580 m of the MFF and detect clear subsurface interfaces in two locations: west MFF between 150 and 155° E and east MFF between 209 and 213° E. Analysis of SHARAD radargrams suggests that the...
The south polar region of the Moon contains areas permanently shadowed from solar illumination, which may provide cold traps for volatiles such as water ice. Previous radar studies have emphasized the search for diagnostic polarization signatures of thick ice in areas close to the pole, but near-surface regolith properties and regional geology are also important to upcoming orbital studies of the...
In a recent Icarus article, Shkuratov and Bondarenko (2001) propose a model for the depth of the lunar regolith based on 70-cm radar observations and near-infrared spectroscopy. This model treats the regolith as a single homogeneous layer of lossy dust, and ignores scattering by buried rocks. There is also an implicit assumption that the regolith substrate is everywhere of uniform morphology. Radar...
Rock-strewn surfaces are apparently common on Mars, and radar backscatter data offer the most direct means for remotely estimating their statistical properties. This paper examines the height statistics of power-law and exponential rock size-frequency distributions, and demonstrates the dependence of root-mean-square (rms) height on horizontal scale as a function of the distribution parameters. In...
Planetary surfaces are better described by nonstationary fractal statistics than those more commonly assumed in current radar scattering models. Therefore, we have developed a radar scattering model applicable to self-affine fractal surfaces when observed near-nadir. The model predicts a family of angular scattering functions that smoothly transition between forms similar to the commonly utilized...
We advocate the use of fractal surface statistics as a simple, quantitative, and general model for planetary surface roughness. We determine the shadowing behavior of a wide range of fractal surfaces using computer simulations, and present an empirical function that reproduces their observed behavior within statistical uncertainties. We compare the shadowing behavior of fractal surfaces to four analytic...
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