The Magellan spacecraft has sent back its first snapshots of Venus, revealing a planet ripped and shredded by powerful stresses that appear far more pervasive than the tectonic forces that generate great earthquakes and catastrophic volcanoes on Earth.
The radar camera aboard the spacecraft, which pierces the layers of dense clouds that normally hide the surface of Venus, snapped a series of long, narrow images of the planet. Everywhere the camera looked it found giant faults and evidence of past volcanic activity.
The first images are part of a "test strip" used to check out the spacecraft's radar system. They will be followed in the coming months with extensive coverage of the planet that is most like the Earth in size and distance from the sun.
Venus' geological history appears "more violent than I had imagined before," project scientist Stephen Saunders said Tuesday during a press conference at the National Aeronautics and Space Administration's Jet Propulsion Laboratory, during which the first photos were released.
Shortly after the images were captured, the spacecraft mysteriously lost contact with Earth and went into a "safe mode" designed to help reestablish communications. The malfunction left scientists at the Pasadena lab wondering for a while if the show was already over.
In fact, only hours after NASA released the first pictures of Venus, JPL engineers again lost contact with Magellan. "They lost it at 7:03 p.m. PDT" while tracking Magellan with a NASA Deep Space Network antenna dish near Canberra, Australia, said spokesman Jim Doyle.
They were uncertain whether the spacecraft was going into an automatic self-protection routine in which it would send a radio beam across the sky in an attempt to re-establish communications with Earth, Doyle said.
If the spacecraft was beaming radio waves while spinning, as it is supposed to do in an emergency, engineers expected to be able to re-establish intermittent contact early today.
After losing contact the first time, engineers at the lab established communications late Friday, after a 14-hour blackout, but no one is certain what caused the problem. The leading theory, according to engineer John Slonski, is that the craft was hit by a cosmic ray or a high-energy particle that confused its computer.
Earlier Tuesday, Slonski said all systems aboard the craft appear "healthy," and Magellan is set to begin its scientific exploration of nearly the entire surface of Venus early next month.
The craft's radar system will continually scan a narrow band on the planet's surface, about 12 miles wide, as Magellan orbits between 180 and 1,200 miles above ground. The snapshots released Tuesday covered several short stretches, ranging from 50 to 90 miles long, captured during 1 1/2 orbits of the blisteringly hot planet, which has a surface temperature of 900 degrees Fahrenheit.
Saunders, a planetary geologist, found many features in the images that reminded him of places on Earth, ranging from the Rocky Mountains to the volcanoes of Hawaii, but he said he had not expected to find so much faulting.
"I am somewhat surprised at the degree of fracturing (from quake-like activity)," Saunders said. "We found it every place we looked."
Saunders said the evidence suggests that Venus differs from the Earth in that "Venus quakes" appear to have happened over wide regions, rather than being concentrated along the boundaries of giant tectonic plates. On Earth, most seismic activity is generated in areas where at least two plates grind against each other--the process that created the San Andreas Fault in California.
Saunders cautioned that Magellan's first glimpse may be misleading.
"Maybe, just by happenstance, we started out by looking at one of the most active regions on Venus," he said.
It is a tantalizing and all-too-brief look for scientists who have waited for years for Magellan to perform. The thousands of images it is programmed to send back over the next two years are expected to be 10 times sharper than radar images returned by two Soviet spacecraft in 1983.
The photos released Tuesday were "just a crack in the door," Saunders said. "I'm looking down through a narrow slit, and we are seeing things we've never seen before."
The images were taken as the spacecraft zipped over a major volcanic area called Beta Regio. Saunders said its structure probably resembles the southern San Andreas Fault near the Salton Sea that is hidden several miles under the ground.
More "slits" will be scanned over the coming weeks and wedded together into a mosaic of the surface of Venus. Scientists hope to be able to draw firm conclusions on the geological history and current nature of the planet.