The group that laid the groundwork for the Internet and self-driving cars is opening up about how it helps invent the future.

DARPA, the research arm of the U.S. Department of Defense, has a track record of nurturing great inventions -- not something the government is typically known for. DARPA played a role in the invention of the computer mouse and precursors to GPS and Apple's Siri. It funded antenna booms on the Hubble Space Telescope and planes capable of refueling at 44,000 feet.

In a new report released this month, the agency revealed how it creates cutting-edge, world-changing innovation.

For starters, DARPA doesn't like to keep its employees around for long. It has about 220 employees in six offices, most of whom hold their jobs for four or five years. The agency has a 25% annual turnover rate, according to the report. The typical turnover rate in most industries is about 15%.

DARPA employees have their "expiration date" printed prominently on their ID badges, giving them a reminder that time is limited.

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DARPA, founded in 1958 in response to the Russian launch of Sputnik, doesn't fear losing institutional knowledge. In fact, it sees a downside to having long-tenured employees. Workers will point to past failures to prove something can't be done. But new tools may have since emerged, making the goal possible.

If you're working for DARPA, you are likely be asked to take on a grand, seemingly impossible challenge.

"If half the people don't respond to a publicly-announced challenge saying it's impossible, we haven't set the bar high enough," said Phillip Alvelda, a program manager at DARPA.

"No idea is too crazy. The reaction is never, 'That's impossible.' We say, 'How would you do that? How would you get there? Write down the steps,'" said Barry Pallota, deputy director of the biological technologies office.

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Like all innovative places, DARPA is open to failure. In 2011, the organization gave one of its biggest awards to an employee whose high-speed rocket project failed.

By taking on such daring projects, DARPA gives itself a chance to have huge successes. It also relies on a speedy hiring process, which bucks the notoriously slow nature of government hiring.

The reports tells the story of a prospective employee visiting DARPA on a Wednesday. That Friday he interviewed with the agency director. On Monday, the new hire had a security clearance and badge and was moved into his office. A computer and phone line were already waiting.

And once inside DARPA's walls, it's time to deliver.

"If you don't invent the Internet, you get a B," said program manager Matt Hepburn.