Search

In November 2005, we observed the moons of Mars using the Arecibo 2380-MHz (13-cm) radar, obtaining a result for the OC radar albedo of Phobos (0.056 [+ or -] 0.014) consistent with its previously reported radar albedo and implying an upper bound on its near-surface bulk density of 1.6 [+ or -] 0.3 g [cm.sup.-3]. We detected Deimos by radar for the first time, finding its OC radar albedo to be 0.021 [+ or -] 0.006, implying an upper bound on its near-surface density of 1.1 [+ or -] 0.3 g [cm.sup.-3], consistent with a high-porosity regolith. We briefly discuss reasons for these low radar albedos, Deimos' being possibly the lowest of any Solar System body yet observed by radar. Keywords: Mars, satellites; Radar observations; Regoliths

Radar ranging from Arecibo, Puerto Rico, to the 0.5-kilometer near-Earth asteroid 6489 Golevka unambiguously reveals a small nongravitational acceleration caused by the anisotropic thermal emission of absorbed sunlight. The magnitude of this perturbation, known as the Yarkovsky, effect, is a function of the asteroid's mass and surface thermal characteristics. Direct detection of the Yarkovsky effect on asteroids will help constrain their physical properties, such as bulk density, and refine their orbital paths. Based on the strength of the detected perturbation, we estimate the bulk density of Golevka to be [2.7.sup.+0.4.sub.-0.6] grams per cubic centimeter., The Yarkovsky effect is a weak nongravitational acceleration believed to act on asteroids and meteoroids. According to theory (1-6), absorbed solar radiation is re-emitted in the infrared with some delay, [...]

Radar echoes from Earth co-orbital Asteroid 2002 AA29 yield a total-power radar cross section of 2.9 x [10.sup.-5] [km.sup.2] [+ or -] 25%, a circular polarization ratio of SC/OC = 0.26 [+ or -] 0.07, and an echo bandwidth of at least 1.5 Hz. Combining these results with the estimate of its visual absolute magnitude, [H.sub.V] = 25.23 [+ or -] 0.24, from reported Spacewatch photometry indicates an effective diameter of 25 [+ or -] 5 m, a rotation period no longer than 33 min, and an average surface bulk density no larger than 2.0 g [cm.sup.-3]; the asteroid is radar dark and optically bright, and its statistically most likely spectral class is S. The [H.sub.V] estimate from LINEAR photometry (23.58 [+ or -] 0.38) is not compatible with either Spacewatch's [H.sub.V] or our radar results. If a bias this large were generally present in LINEAR's estimates of [H.sub.V] for asteroids it has discovered or observed, then estimates of the current completeness of the Spaceguard Survey would have to be revised downward. Keywords: Asteroids; Radar; Photometry

Radar Images of Asteroid 1989 PB THIS ARTICLE PRESENTS RADAR OBSERVATIONS THAT PROVIDE two-dimensional images of a kilometer-sized asteroid and, quite unexpectedly, reveal it to have an extremely bifurcated, 'double-lobed' [...]

Author(s): Bruce A. Campbell (corresponding author) [1]; Donald B. Campbell [2]; John F. Chandler [3]; Alice A. Hine [4]; Michael C. Nolan [4]; Phillip J. Perillat [4] We have used [...]

Styles of Volcanism on Venus: New Arecibo High Resolution Radar Data VOLCANISM IS ONE OF THE FUNDAMENTAL processes of heat transfer from planetary interiors [1]. The location of volcanic deposits [...]