Everyone in Japan knows the exact date on which the Age of Robots began: April 7, 2003, Astro Boy's birthday.

Astro Boy was the cartoon robot created by legendary Japanese animator Osamu Tezuka in 1951. Featured in a hit TV series in Japan and the United States in the 1960s, Astro Boy had rockets in his legs, searchlights in his eyes, and machine guns in his shorts. He inspired a generation of roboticists. Tezuka set his birthday in 2003, because he was sure that by then autonomous humanoid machines would be everywhere.

Tezuka wasn't that far off-in Japan, anyway. The most visible example is a herd of toys ("entertainment robots," in the jargon) jamming upscale-Tokyo-store shelves, among them Sony's well-known Aibo robot dog, Sega Toys' Poo-chi (a big-headed, blue-eared pooch), and scheduled for spring, a robot cat from toymaker Bandai.

The toys are just the beginning. Japan's Ministry of Economy, Trade, and Industry plans for robots to become one of the country's key industries, as important as automobiles and consumer electronics. The government is disbursing $28 million this year for robot development; industrial powerhouses like Fujitsu, Honda, Toyota, and Kawada also have robot projects. By 2010, the ministry hopes, full-fledged, humanoid robots will be common sights in middle-class homes.

Some scientists outside Japan have disparaged this goal, because robots, strong and heavy, will pose a danger to their owners. "What if it thinks Grandma's head is a vase and tries to put it away?" asks Mark W. Tilden, a well-known U.S. researcher who has built robots for NASA and is now working on the design of a walking toy robot called Robosapien. Building machines to perform even simple tasks like dish-washing is a formidable challenge: they will have to recognize the difference between a plate and a Frisbee, manipulate glasses and crockery without breaking them, and stick knives and forks in the appropriate drawer. The problems are compounded for humanoid robots. Simply reproducing the bipedal walk has been a near intractable engineering challenge. "And after all that, you're building a half-million-dollar machine to wash the dishes," Tilden says.