by Corey S. Powell
For at least the next five years, NASA's Cassini spacecraft, six tons ofbrute technology laboriously wending its way to Saturn and its giant moonTitan, will serve nicely as a bloated billboard with this message: The era ofbig, unmanned space missions is over. Not only did the craft's considerableheft force an impressively circuitous route that depends on the gravitationalpull of three heavenly bodies, but its $2 billion cost clashed ominously withthe U.S. space agency's shrinking budget.
Just as the extinction of the dinosaurs cleared a place for little, lithemammals, so the termination of huge missions like Cassini will createopportunities for petite but powerful explorers. Under strict orders fromNASA 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 nolarger than a computer chip. The technologies will be seen in the realworld surprisingly soon.
At the Jet Propulsion Laboratory in Pasadena, California, ground zero forNASA's tightened focus, a tiny rover called MUSES-CN symbolizes themerits of miniaturization. MUSES resembles a drastically downsizedversion of Sojourner, the remote-control chariot that enchanted the publictwo summers ago as it rolled across Mars. The reduced rover measures justsix inches long and weighs 42 ounces. Its size will allow it to ridepiggyback on the already-planned Japanese MUSES-C probe, to belaunched at the asteroid Nereus in 2002.
MUSES is only a beginning. Rover mastermind Brian Wilcox is developingtiny rovers that weigh no more than a few ounces. Another little buggymay ride aboard the Near-Earth Asteroid Prospector--history's firstprivately funded deep-space probe. The European Space Agency isworking on ROSA, a six-wheeled robot designed to tackle the worst terrainMars 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 pressurizedgas-driven hammer that burrows eagerly underground.
The spacecraft that fly the rovers are likewise dieting. Barry Hebert'smicro-spacecraft group at JPL is building radically downsized vehicles,weighing as little as two pounds. Several could fly into space on top of asingle inexpensive Pegasus missile. They could then "set up a virtualnetwork--a kind of Internet in space," Hebert says. Networking wouldallow coordinated activities such as observing an asteroid from all sides atonce or building a complex telescope that could reveal details far too fineeven for the Hubble Space Telescope. Hebert promises test flights of hisminiature 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 collectorto extremely high speeds. Later this year, the space shuttle may carry asolar sail into Earth orbit to prove the concept works.
A few technological visionaries, such as inventor Forrest Bishop of theInstitute of Atomic-Scale Engineering, are planning machines that cantravel to other star systems and reconfigure themselves molecule bymolecule. 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 embracesuch dreaming. But that doesn't bother Bishop. "In the long term," he says,"space will become a private venture. Bureaucrats are not going to colonizethe solar system."
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