Jan 28 1985
From The Space Library
NASA announced it had received signals from the USSR's Venera Halley space probes at its Deep Space Network's (DSN) 210-foot antenna at Goldstone, California. The USSR had agreed that Vega-1 and 2, launched in December 1984, would carry experiments for joint U.S./French research.
For the June 1985 experiment, each spacecraft would drop into the Venusian atmosphere an instrument-laden balloon, which would float free in the middle, most active layer, of Venus's three-tiered cloud system. Transmitters on the balloons would continually send signals to earth during the two-day lifetime of each balloon. Three globally-placed, hypersensitive dish antennas of NASA's DSN, part of an international network of radio astronomy antennas organized by the Centre National d’Etudes Spatiales for the study, would receive the signals. Using data received from the combined array of at least 10 antennas worldwide, in addition to that from the USSR's network, scientists could calculate in detail the balloons' locations and motions.
Scientists would use a radio astronomy technique known as Very Long Baseline Interferometry (VLBI) to measure balloon velocity and hence Venus's wind velocity with a precision of approximately two miles per hr. at a distance of 67 million miles from earth. Scientists hoped data obtained would help further understanding of the complex Venusian weather system.
The DSN antennas would also receive data from the other scientific instruments on the balloon gondola, including instruments to measure lightning flash frequency, wind gusts' vertical velocity, atmospheric temperature and pressure, and cloud location and density.
Understanding turbulence and wave-type motions in clouds was important because scientists believed Venus's cloud layers to be the driving gear of the planet's multilayered weather machine. For example, scientists hoped data would explain why the atmosphere at Venus's cloud tops circled the planet at 250 miles per hr. as compared to near-calm on the surface.
By studying the atmospheric dynamics on Venus and other planets, scientists hoped to understand atmospheric processes in general in order to characterize all planets, including earth, in terms of a general set of physical laws. (NASA Release 85-13)
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