A radio experiment using the Magellan spacecraft's powerful transmitter probed deeper into the atmosphere of Venus than Magellan Project science team members expected, a spokesman at NASA's Jet Propulsion Laboratory said.

Project Scientist Dr. Steve Saunders said the experiment was suggested by Professor Paul Steffes of Georgia Institute of Technology, and used a technique known as radio occultation.

Magellan is mapping the surface of Venus with imaging radar. Steffes proposed the experiment using a technique that has been used in previous planetary missions, including the Voyager encounters of the outer planets and the currently functioning Pioneer Venus Orbiter. But the large antenna and powerful transmitter aboard Magellan made it possible to probe deeper into the atmosphere with more accuracy than ever before.

The data received from the experiment, which sends a radio beam through the atmosphere as it dives behind the planet in its orbit, is still being analyzed.

When the data are completely reduced, accurate profiles of the temperature and pressure in the Venus atmosphere will be obtained, Steffes said. Also, an enhanced profile of the abundance of gaseous sulfuric acid which condenses to form the clouds of Venus will also be acquired.

The experiment was conducted during three successive orbits on the same day, October 5. Since the experiment was conducted three times the same day, and any short term variation in the meteorology of Venus, at the location probed, could be detected.

But to be most useful, a large number of such measurements conducted at different times and locations would be made, which would give a better picture of how the climate of Venus varies with time and location. Steffes said he hoped that such an opportunity might occur in late 1992.

The October 5 experiment was planned and conducted by a group of scientists and engineers including Magellan Science Team member Professor G. Leonard Tyler of Stanford University and Steffes.

Preliminary analysis of the new radio occultation data indicates the experiment probed deep into Venus' atmosphere, reaching to just 33.5 kilometers (20.8 miles) above the surface.

The Magellan Project is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science and Applications.

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