Scientists report indications of volcanic activity on Venus
Even though it is named for the mythic goddess of love, there is nothing very fetching about the planet Venus. It is veiled in a dense atmosphere of carbon dioxide, laced with corrosive clouds of sulfuric acid, and its surface temperatures hover around 900° F. Liquid water, if it ever existed, has long since vanished. Nothing, not even the hardiest microbes, could survive for long in this cauldron.
Yet Venus, the second planet from the sun (Mercury is closest), shares significant characteristics with its neighbor, earth. It is nearly the same size and density, and by astronomy's vast measures, is a similar distance from the sun (67 million miles vs. 93 million for the earth). Now it appears that Venus resembles the earth in still another way. Scientists announced last week that Venus seems to be pockmarked with giant volcanoes, at least one of which erupted as recently as five years ago.
The evidence comes from a remarkable automated observatory called Pioneer Venus. Since late in 1978 the 810-lb. machine has been circling Venus, probing it with a battery of instruments, including radar. The devices, said Pioneer Venus scientists meeting at NASA's Ames Research Center near Mountain View, Calif, have revealed that under Venus' clouds is a landscape almost as dramatic as the earth's: sprawling plateaus, mountains as high as Everest and great chasms similar to terrestrial rift valleys.
Analyzing data from Pioneer's ultraviolet spectrometer, the University of Colorado's Larry Esposito found that 1978 sulfur dioxide levels in the Venusian atmosphere were 50 times as high as expected. Since then, the sulfur dioxide lev els have been slowly tapering off, just as they drop after a major volcanic eruption on earth. Another investigator, Fred Scarf of TRW Inc., the spacecraft's builders, disclosed that an on-board instrument called a plasma-wave detector had recorded repeated lightning discharges over two mountain regions. On earth, such electrical activity commonly accompanies volcanic outbursts.
Still more tantalizing, the lightning was detected above two mountainous regions called Beta and Atla, which sit astride the Venusian equator. These areas appear to be supported by younger, denser rock, a characteristic of terrestrial volcanoes. (Intriguingly, this was deduced from precise tracking of the spacecraft.
When it dipped ever so slightly over certain areas of Venus, the scientists concluded that it was flying over denser regions that exerted a greater gravitational tug on the ship.) In addition, radar reconnaissance showed material radiating from Beta that looked uncannily like recent lava flows.
The researchers are elated about their long-distance snooping, but not simply for scholarly reasons. They note that a planet like Venus provides a real-life laboratory for understanding such essential questions as global weather patterns and the spread of acid rain, whose most corrosive ingredient is sulfur dioxide. Venus is also valuable for studying the buildup of carbon dioxide in the atmosphere, which increases global temperatures. Says the U.S. Geological Survey's Harold Masursky of the latest Venus findings: "These are not just nice things to know. They may be vital to our survival."