The Department of Homeland Security, given the difficult task of trying to divine al Qaeda's future methods of attack on the United States, is seeking advice from some unexpected sources these days: futurists, philosophers, software programmers, a pop musician and a thriller writer.

Picking the brains of people with offbeat specialties and life experiences is the latest tactic in the government's efforts to get inside the heads of worldwide terrorists. Homeland Security's Analytic Red Cell office employs a tactic that has been used for decades by U.S. intelligence agencies, the Pentagon and large corporations -- gathering together people from outside their insular bureaucracies to arrive at fresh insights.

"We try to anticipate four, five moves ahead in the mind of our adversary," said Jon Nowick, director of the Analytic Red Cell program, which is part of the department's Information Analysis and Infrastructure Protection, or intelligence, unit. "We paint a picture where there are no dots to connect."

Typically the Red Cell team assembles 20 or so participants for a day-long session at leased offices in the Washington area. Each session divides into smaller groups and takes up a different question, such as: If you were a terrorist, how would you target the G-8 economic summit, held last week in Georgia? Another recent topic was: Why haven't terrorists hit the United States since Sept. 11, 2001?

The results are compared with terrorism analysis from Homeland Security's intelligence professionals who examine real-life threat information. Written reports on Red Cell's sessions are then forwarded to terrorism analysts inside the department, as well as to local and state police and security experts in private industry. Most Red Cell reports note they are "alternative assessments intended to provoke thought and stimulate discussion."

The Red Cell has not previously publicized itself. Its leaders talked to a reporter recently in part to quell rumors that one of the team's threat scenarios -- such as an assault on a chemical plant -- might be a real-life event.

Many participants have not worked much with the government before.

"When I got the call, I was floored," said Brad Meltzer, the author of several successful Washington thrillers, recalling his talk with the Homeland Security official who recruited him. "They said, 'We want people who think differently from the ones we have on staff.' "

He declined to say what scenario his session focused on -- like other participants, he had to sign a nondisclosure agreement. But Meltzer said among the participants in his session were a psychologist, a philosopher, a professor of Middle Eastern terrorism and employees of the CIA and FBI.

Red Cell has finished 10 reports this year, and six more are being prepared -- quickening the pace of reports in its first months of operation last year. Homeland Security officials provided only vague descriptions of a few of their topics.

In one early session last summer, Red Cell examined the vulnerabilities of commercial aviation. The participants, including aviation professionals, noted possible methods for terrorists to get bomb-bearing parcels onto passenger planes. The findings helped inform the department's rules on air cargo, officials said.

Last fall, as Hurricane Isabel approached the mid-Atlantic states, another session warned of specific ways terrorists could launch an attack to exploit local authorities' preoccupation with the storm.

A typical session will examine a sector of critical infrastructure -- gas pipelines, say -- and could include Special Forces experts on attack tactics, scientists who understand pipeline engineering and corporate security officers who know the workings of that industry.

"Homeland Security is on to a good thing," said Daniel S. Gressang IV, who trains intelligence officers at the Pentagon's Joint Military Intelligence College and who has advised the Red Cell team. "They're getting at some creative ideas."

"I'm a huge fan of red teaming" efforts like Homeland Security's, said Frank Cilluffo, a former domestic defense official in the Clinton and Bush White Houses who is now head of George Washington University's homeland security program. "It's an important learning tool."

The CIA has used red teaming for decades -- in the 1970s, Harvard University Russia expert Richard Pipes ran a "Team B" study that asserted the agency had underestimated Soviet military strength. Navy Seals have used Red Cell teams to mount assaults on military bases to test their security.

The Pentagon has gathered hundreds of Red Teams to reexamine assumptions about foreign militaries and their weapon systems, at times recruiting the services of Web designers, historians and screenwriters.

Meltzer, a Montgomery County resident, reckons Homeland Security picked him in part because some of his novels include closely held details about the physical layout of some key Washington landmarks, and descriptions of how people can sneak around and in them.

In his novel "The First Counsel," a young White House lawyer falls in love with the president's daughter, and the two evade Secret Service minders as they prowl tunnels beneath the White House. These sections of his books were based on careful reporting, and he had retired Secret Service agents vet them, Meltzer said.

Meltzer said he was impressed by the Red Cell team's ingenuity and seriousness. "If I can help the government on terrorism," he said, "that's better than being on the bestseller list."

Frank Cilluffo, a former domestic defense official, said he sees great value in devising and analyzing possible terrorism scenarios.Montgomery County's Brad Meltzer, author of "The First Counsel," has participated in Homeland Security's Analytic Red Cell.