For at least the next five years, NASA's Cassini spacecraft, six tons of brute technology laboriously wending its way to Saturn and its giant moon Titan, will serve nicely as a bloated billboard with this message: The era of big, unmanned space missions is over. Not only did the craft's considerable heft force an impressively circuitous route that depends on the gravitational pull of three heavenly bodies, but its $2 billion cost clashed ominously with the U.S. space agency's shrinking budget.
Just as the extinction of the dinosaurs cleared a place for little, lithe mammals, so the termination of huge missions like Cassini will create opportunities for petite but powerful explorers. Under strict orders from NASA administrator Daniel Goldin, whose oft-repeated mantra is "better, faster, cheaper," the agency is moving toward ideas reminiscent of science- fiction novels--robots that could fit on a spoon, solar sails, and rockets no larger than a computer chip. The technologies will be seen in the real world surprisingly soon.
At the Jet Propulsion Laboratory in Pasadena, California, ground zero for NASA's tightened focus, a tiny rover called MUSES-CN symbolizes the merits of miniaturization. MUSES resembles a drastically downsized version of Sojourner, the remote-control chariot that enchanted the public two summers ago as it rolled across Mars. The reduced rover measures just six inches long and weighs 42 ounces. Its size will allow it to ride piggyback on the already-planned Japanese MUSES-C probe, to be launched at the asteroid Nereus in 2002.
MUSES is only a beginning. Rover mastermind Brian Wilcox is developing tiny rovers that weigh no more than a few ounces. Another little buggy may ride aboard the Near-Earth Asteroid Prospector--history's first privately funded deep-space probe. The European Space Agency is working on ROSA, a six-wheeled robot designed to tackle the worst terrain Mars has to offer. Other exotic vehicles are in the works at JPL as well, such as a "subsurface explorer"--a two-inch-wide rod with a pressurized gas-driven hammer that burrows eagerly underground.
The spacecraft that fly the rovers are likewise dieting. Barry Hebert's micro-spacecraft group at JPL is building radically downsized vehicles, weighing as little as two pounds. Several could fly into space on top of a single inexpensive Pegasus missile. They could then "set up a virtual network--a kind of Internet in space," Hebert says. Networking would allow coordinated activities such as observing an asteroid from all sides at once or building a complex telescope that could reveal details far too fine even for the Hubble Space Telescope. Hebert promises test flights of his miniature spacecraft within the next couple of years.
Featherweight spacecraft are a perfect fit with solar-sail propulsion. Radiation from the sun could accelerate a huge but very thin light collector to extremely high speeds. Later this year, the space shuttle may carry a solar sail into Earth orbit to prove the concept works.
A few technological visionaries, such as inventor Forrest Bishop of the Institute of Atomic-Scale Engineering, are planning machines that can travel to other star systems and reconfigure themselves molecule by molecule. Once they reach their target, they will seek out raw materials, build sensors and an antenna, then relay images back home.
NASA scientists, staring at tight funding restrictions, dare not embrace such dreaming. But that doesn't bother Bishop. "In the long term," he says, "space will become a private venture. Bureaucrats are not going to colonize the solar system."
