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We report 8510-MHz (3.5-cm) radar observations of the Earth-crossing asteroid (ECA) 6489 Golevka (1991 JX) obtained between June 3 and June 15, 1995, at Goldstone, the Very Large Array and the Evpatoria (Ukraine) and Kashima (Japan) radio antennas. One-dimensional Doppler spectra are used to estimate the object's convex hull, refine the ephemeris, and yield four possible pole directions. Three-dimensional...
Physical evidence of life (physical biomarkers) from the deposits of carbonate hot springs were documented at the scale of microorganisms-submillimeter to submicrometer. The four moderate-temperature (57 to 72 o C), neutral pH springs reported on in this study, support diverse communities of bacteria adapted to specific physical and chemical conditions. Some of the microbes coexist with travertine...
We report detailed results of Arecibo and Goldstone radar observations of 30 mainbelt asteroids (MBAs) during 1980–1995. In addition to estimates of radar cross section, radar albedo, and circular polarization ratio, we obtain new constraints on pole direction for several asteroids, with those for 21 Lutetia being particularly restrictive. We carry out statistical analyses of disk-integrated properties...
We report Doppler-only (cw) and delay-Doppler radar observations of Bacchus obtained at Goldstone at a transmitter frequency of 8510 MHz (3.5 cm) on 1996 March 22, 24, and 29. Weighted, optimally filtered sums of cw and delay-Doppler echoes achieve signal-to-noise ratios of ∼80 and ∼25, respectively, and cover about 180° of rotation phase (period=14.90 h; Pravec et al. 1998). Our cw observations place...
We report Doppler-only (cw) radar observations of near-Earth asteroid 1991 CS obtained at Goldstone at a transmitter frequency of 8510 MHz (3.5 cm) on 1996 August 26, 27, 28, and 29. Weighted, optimally filtered sums of cw echoes achieve signal-to-noise ratios in excess of 300 per day and thoroughly cover the asteroid in rotation phase (synodic period=2.39 h, obtained photometrically by P. Pravecet...
We report initial results of daily delay/Doppler observations of Toutatis with the Goldstone 8510-MHz (3.5-cm) radar during Nov. 25–Dec. 3, 1996. Using the physical model of Toutatis derived from 1992 radar observations (Hudson and Ostro 1995,Science270, 84–86) to analyze the new data, we obtain refined estimates of the asteroid's orbit, spin state, and surface properties. The asteroid's centimeter-to-decameter...
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