The Defense Advanced Research Projects Agency will kick off the DARPA Network Challenge this weekend to research how social networking and the Internet can help solve broad, time-critical challenges.

DARPA is offering a $40,000 prize to the first person who can find 10 large, red weather balloons that have been moored at locations across the United States. There's a catch: The balloons, to be put up in "readily accessible locations" visible from nearby roads, will only be up from 10 a.m. until 4 p.m. Eastern on Saturday, December 5. People will have until December 14 to submit their findings.

The challenge is open to anyone except federal government employees, DARPA contractors, and their spouses and dependents. Hundreds have registered to participate and have already begun using the Internet to recruit others and collaborate.

A Facebook group established for the challenge had 555 members at last count. One man set up a Google map marking locations of individuals involved in the challenge. Messages on Facebook and a wiki set up for the network challenge are filled with claims that people will share prize money or send it to a charity as an enticement to get others to help. One group plans to synthesize publicly available information and interpret it, hopefully improving its chances. Others suggest setting up red herrings to confuse participants.

DARPA is using the Network Challenge to mark the Internet's 40th birthday. "In the 40 years since this breakthrough, the Internet has become an integral part of society and the global economy," DARPA director Regina Dugan said in a statement. "The DARPA Network Challenge explores the unprecedented ability of the Internet to bring people together to solve tough problems."

The effort is one of a series of DARPA-sponsored challenges, which have included a $2 million prize for the builders of a robot car that drove itself over a 131-mile desert course in California.

If no one finds all 10 balloons, DARPA will award the prize to an entrant who locates at least five of them.

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