Ronald Greeley is a busy man these days.
The soft-spoken geologist from Arizona State University is a key player in a planetary doubleheader: this week's unprecedented landing of a rover on the surface of Mars and Galileo's continuing mission at Jupiter.
Each mission is expected to shed light on whether other bodies in our solar system once had environments that could have nurtured primitive life. The first clues about those environments will be read in rocks - and in the case of Jupiter's moon Europa, in its ice.
Mr. Greeley is a member of Mars Pathfinder imaging team led by Peter Smith of the University of Arizona at Tucson. Pathfinder's 3-D camera, using a special set of color filters, will yield images that the team is using to build an itinerary for Sojourner, the tiny robotic rover, to follow. The camera will also help Greeley and other scientists analyze the type of rocks nearby.
Already, his appetite has been whetted. Pictures from the surface of Mars show what the science team has dubbed "Twin Peaks" - a pair of hills a little more than a mile from the lander and several hundreds of meters high. A detailed photo of one of the peaks shows a feature dubbed the "Ski Run" for the streak of light-colored material that runs down its slope.
The companion peak shows four or five horizontal stripes, similar to the bands seen on Earth in places like the Grand Canyon. Dr. Greeley offers three possible explanations - all indicating the activity of liquid water.
"I consider myself very lucky" to be in this position, a grinning Greeley says in an interview here at NASA's Jet Propulsion Laboratory (JPL), reflecting on a career that grew not from the lure of space, but from the tug of Earth's world on a curious youngster.
Born in Columbus, Ohio, Greeley was in the seventh grade when his interest in geology blossomed. "My father was being transferred to California from back East," he recalls. His fascination with rocks grew with each passing mile as the family drove along the old US Route 66 through New Mexico and Arizona. There, the highway laced its way between mesas and past ancient lava flows, salmon-striped sandstone buttes, and the meteor crater at Winslow, Ariz.
"As we got into the West, all the rocks were nicely exposed," he recalls. "They weren't covered up with trees and vegetation. I thought, 'Wow, geology is super!' That was the turning point."
He went on to get his PhD in geology in 1966 at the University of Missouri at Rolla. Within a year, he was at the National Aeronautics and Space Administration's Ames Research Center in Mountain View, Calif. One of the program's goals was to better understand the moon's geological past. Greeley says that's when he realized "you could do geology on planets other than Earth."
His interest turned to Mars with Mariner 9, a mission that returned images of volcanoes and other Earthlike features in the 1970s. Greeley was involved in the 1989 Magellan mission to Venus, which yielded stunning radar maps of 98 percent of the planet's surface. And he's done research with radar-mapping equipment on the space shuttle.
NASA's emphasis on "faster, cheaper, better" solar-system missions represents the biggest change in planetary exploration in years, Greeley says. Completed in three years at a cost of $196 million, Pathfinder is testing technologies for future missions as well as giving researchers their first opportunity in 21 years to explore the Martian surface.
Eventually, JPL officials say, they hope to produce technologies tiny enough to build scientific probes that aren't much larger than a couple of shoe boxes. The goal is to increase the frequency of launches to as many as one a month.
"For the most part, this is a positive thing," Greeley says. "It's resulting in a very rich planetary exploration program."
More Mars missions, a return to Europa, and a probe to take samples of a comet's tail are either planned or anticipated.
Yet, he adds, "we have to remember that there's a role for the big guys, too," pointing to a full-scale model of the Pioneer craft that provided the first closeup views of the giant outer planets. "Some expeditions really require the larger, more capable spacecraft in terms of the number of instruments."
"It takes so long to get there that if you're only carrying a small payload, it could be a long time before you get to go back to make the whole suite of measurements you'd like. So any mission that requires an extended travel time or development time needs to be looked at to see if the small-mission mode makes sense."
That said, Greeley is upbeat about the missions NASA and the planetary-science community have laid out. "Having the community propose a mission and then empowering the principal investigator to follow through, that's very exciting," he says. So is a proposal that NASA add a category to future budgets for outer-planet missions. Under this approach, Congress would appropriate money for the category, and NASA would dispense it to individual missions. "One does not have to go to Congress for each mission," he says.
But the faster-cheaper-better approach has potential drawbacks that bear watching, Greeley adds. They center on the time and money available for analyzing and learning from the data produced.
"With fewer engineers and JPL types, that work still has to be done." he says. "We're finding that more of our younger scientists are doing the operational end of things. Some of our younger PhDs are spending all of their time doing mission planning and don't have time to do the analysis.
"Not that we would want to see missions canceled," he adds hastily, "but it's a problem that needs to be addressed."