Magellan Data From Venus Is Vast, Complex

The Magellan spacecraft has responded to more than 80,000 commands and has sent back more bits of data from Venus than was collected during the entire missions of the Voyager, Viking and Mariner spacecrafts, scientists said Tuesday.

Yet despite images that tell experts more about the hot, smoldering planet than they know about some areas of the moon, scientists continue to disagree over the powerful forces that molded the tortured surface of Venus.

Magellan uses radar to pierce the dense clouds that mask the surface of Venus, and scientists at the Jet Propulsion Laboratory are using that data to piece together giant mosaics of the surface of the planet that is most like the Earth, yet so very different.

The volume of data is so staggering and the geologic processes on Venus are so complex that scientists are still struggling to understand some of the fundamental forces. Some definitive answers possibly may not come for a year, Magellan chief scientist Stephen Saunders told JPL scientists Tuesday.

Nevertheless, the most detailed picture ever of Venus continues to unfold. Magellan has revealed towering mountains created by volcanic forces, surrounded by great rivers of hardened lava.

Some areas look like the Hawaiian Islands, minus the vegetation and the Pacific Ocean. Other scenes are similar to geological structures found on Earth, including the layered rock throughout much of California that was twisted and warped by the movement of the giant tectonic plates that make up the surface of the Earth.

That is a little bit of a puzzle because Venus is not believed to have large tectonic plates of hardened, brittle rock like those found on Earth. The collision of tectonic plates creates Earth’s mountains and the volcanoes.

Instead, the surface of Venus is believed to be much more elastic, and there is no reason to believe that it is broken into large plates. But Saunders said Tuesday that there is clear evidence of some folding similar to the processes that created the mountain ranges of Southern California.

Much of the scientific work consists of analyzing what geologist Laurence Soderblom of the U.S. Geological Survey called the “blotches and smudges” on the images created by objects that ripped through the dense atmosphere of Venus and struck the surface. The atmosphere is 65 times as dense on the surface of Venus as it is on Earth, so only the larger and hardier meteoroids make it through the atmosphere.

The patterns of craters caused by impacts from those meteoroids tell scientists much about the composition and even the history of the planet. The entire surface of the planet should be covered with craters, but there are large areas where there are none. That tells scientists that some process--most likely flowing lava--has wiped out craters in recent geological history.

That suggests Venus is still very much alive volcanically, although scientists have seen no direct evidence of active volcanoes so far.

Saunders believes he will find one soon. “I’m positive it’s there,” he said.