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Surface reflections of Pioneer Venus Probe radio signals
Author(s) -
Croft Thomas A.
Publication year - 1980
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl007i007p00521
Subject(s) - venus , atmosphere of venus , atmosphere (unit) , refraction , physics , radio occultation , geology , antenna (radio) , doppler effect , remote sensing , optics , astrobiology , astronomy , ionosphere , meteorology , telecommunications , computer science
As the four Pioneer Venus probes fell within the atmosphere toward the surface of Venus, each of them transmitted a radio signal directly to Earth. Because of the relatively broad antenna beam‐width of these small probes, some of the transmitted power went down to the surface of Venus. I report here the discovery that the radio signals scattered off the surface are not only detectable but that their characteristics can be determined with a surprising degree of certainty. From these characteristics one can determine parameters of the Venusian atmospheric winds and of the surface that promise to be useful. Most of the scattered energy is that which originally radiated from the probes in a near‐horizontal direction; the downward‐directed radiation is detectable but much weaker. Refraction in the atmosphere of Venus clearly plays a significant role in establishing both the strength of scatter and its Doppler shift. For this first report, I stress the aspects of analysis that bear on the identification of these weak echoes.