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More, indeed. Though Pathfinder and Surveyor will be claiming the attention of Mars scientists for the immediate future, there's a small fleet of similar ships poised to fly. Every 26 months the orbital minuet that Earth and Mars dance around the sun brings them close enough to make interplanetary travel practical. NASA plans to take advantage of those exploratory windows, sending at least three other lander-orbiter pairs to the Red Planet in 1998, 2001 and 2003. In 2005 the agency hopes to exceed even these ambitious plans, launching the first-ever round-trip Mars ship, one capable of landing somewhere on the surface, then flying back to Earth carrying with it a few precious handfuls of rock and soil.
Mars is not the only place the new budget ships will visit. Last spring planetary scientists were buzzing over images returned by the Galileo space probe that provided evidence of a water ocean beneath a thin rind of ice on Jupiter's moon Europa. Where there's water, there's usually heat, and where there's water and heat, there could well be life. Sometime after 2000, NASA is hoping to launch a Europa probe that will orbit the Jovian moon at an altitude of 60 miles--about the same distance at which Apollo spacecraft used to orbit Earth's moon--photographing its surface and taking radar soundings to look for water beneath its crust. If the radar picks up the telltale echoes of liquid, another spacecraft would be sent to land on Europa. Once there it would release a small cylindrical probe with a heated tip that would melt through the ice layer and propel itself through the frigid ocean, looking for signs of life.
Still another spacecraft might be launched to fly by Europa and drop a 20-lb. sphere onto its surface. Striking the frozen crust with the force of a suitcase full of TNT, the cosmic cannonball would release a mushroom cloud of ice particles into space; the mother ship would then fly through the crystalline mist, collect a bit of it and carry it back to Earth for analysis.
Other hoped-for missions include a 13-year, 4 billion-mile-plus journey to Pluto and its companion moon Charon, tentatively set to launch in 2001; a comet-rendezvous mission that will take off in February 1999, fly by Comet Wild 2 in 2004 and fly back home with a bit of material from its diaphanous tail; and perhaps even a much-dreamed-of journey to Neptune's planet-size moon Triton. Says Goldin: "We're going to have the most aggressive exploration of our own solar system in the history of the human species."
Not everyone at NASA is convinced that Goldin's thrift-shop ships are up to the trips. "Faster and cheaper is not necessarily better," says Ray Newburn, a veteran astronomer with 41 years of experience working on J.P.L. missions. "It's nice to have some small missions where you don't have all your eggs in one basket. But you can't always be cheap about missions that go way out and have to last a decade or more."
Rich Terrile, a J.P.L. planetary scientist, doesn't agree. "The new missions are cheap," he says. "So if one fails, it's not the end of the program. We're not going to build the dinosaurs anymore."