Early Results of the 1961 JPL Venus Radar Experiment.

Abstract

view Abstract Citations (10) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Early Results of the 1961 JPL Venus Radar Experiment. Muhleman, Duane O. Abstract A strong radar contact with Venus was made during the 1961 Venus conjunction utilizing the Goldstone, California, radar facilities of the Jet Propulsion Laboratory. Observations were made nearly daily from March to through May to. A t2.5-cm CW signal was transmitted with an 85-ft parabolic antenna, and the returned signal was received with a second 85-ft antenna. The transmitted frequency stability was held to within 1 cps for the signal-delay time. This reference signal was used to synchronously detect the returned signal and to determine the Doppler shift with an accuracy of 1 cps which corresponds to 0.07 m/sec. The transmitter was also keyed off and on for purposes of making unambiguous range measurements (time-of-flight measurements). Preliminary results of an astronomical unit determination yield a value approximately 60 000 km larger than the value determined by Kabe (1960). The accuracy of the data suggests the possible improvement of the Venus ephemeris. Analysis of the returned signal indicates a reflectivity relative to a perfectly conducting sphere of about 10% at this wavelength as compared with the lunar reflectivity of about 2 %. Doppler spreading of the returned signal due to the rotation of Venus strongly indicates synchronous rotation of the planet. The spectrum of the Doppler-spread signal is very similar in shape to the spectrum computed from a lunar-reflected signal at the same wavelength indicating similar backscattering characteristics. The analysis of the change in spectral width as a function of time for purposes of determining the Venus rotation axis orientation has not been completed as yet. Publication: The Astronomical Journal Pub Date: September 1961 DOI: 10.1086/108422 Bibcode: 1961AJ.....66..292M full text sources ADS |