(CBS) A hushed computer room in an undisclosed location is the control center of the American debt machine, CBS News correspondent Anthony Mason reports.

CBS News entered the auction room of the Treasury Department's Bureau of Public Debt -- the first time a TV camera has ever been allowed inside.

"So what all these people are doing is monitoring the bidding that's coming in from all the different dealers," said Undersecretary of the Treasury Anthony Ryan.

It is where the U.S. government raises the money it needs to pay its bills. In other words, it is the world's biggest borrower flashing its credit cards.

"There is real money at stake," Ryan said. "Today we're auctioning off $13 billion of 10-year Treasury notes."

Treasury notes are basically IOUs that the government pays back with interest. In this auction, that amounts to a $13 billion loan. Without that money, and a few of these auctions every week, the government would shut down. Debt is now this nation's lifeblood.

Who's buying the debt?

"Well, a lot of people," Ryan said.

Pension funds, mutual funds, individuals, institutions and foreign governments compete to buy the U.S. treasuries by offering the cheapest interest rate.

"You're trying to get the lowest interest rate for the U.S. government?" Mason asked.

"That's right," Ryan said.

How much money passes through the room every year?

"Approximately $4 trillion," Ryan said.

That's nearly half of what America owes the world - now a mind-numbing $9.3 trillion.

There was a time when the cash the U.S. government needed for its daily operations was kept in a Treasury Department vault, across the street from the White House. But there isn't a safe in the world big enough to do that anymore, because the national debt is growing at nearly $1 million a minute.

"It's $31,027.00 per American," said Sen. Tom Coburn, R-Okla. "We have great risk that we're gonna become a mediocre country that's in debt and we're gonna handcuff and put a millstone around the next two generations because we won't act like adults now."

"I think the concern about the national debt is what we're doing with it," said Charles Wheelan, author of Naked Economics.

Last year alone, the United States spent $430 billion just on interest payments - that's nearly as much as we spent on education.

"Albert Einstein called compound interest one of the great wonders of the world. It adds up really fast," Wheelan said. "And I'm not sure we fully appreciate, either on the public or on the private level, how quickly you can get in borrowing trouble."

The heavy bidding in the auction shows U.S. debt is highly desirable.

"And at least so far this has always been a viable investment?" Mason asked.

"It has indeed. We have never defaulted," Ryan said. "And we have always paid interest on time. And we have always repaid principle."

But some see a day of reckoning approaching, when the world loses faith in the free-spending U.S. economy, when interest rates soar, when the United States finally sinks under the weight of its own debt.

"Is this the most likely scenario? No," Wheelan said. "Is it something we should be planning for? Absolutely."

The Treasury's auction room is kept secret because any disruption would send shock waves through the world financial markets. In fact, during every debt auction two back-up rooms, in New York and West Virginia, are always on standby.