The federal student loan program seemed like a great idea back in 1965: Borrow to go to college now, pay it back later when you have a job.

But many borrowers these days are close to flunking out, tripped up by painful real-life lessons in math and economics.

Surging above $1 trillion, U.S. student loan debt has surpassed credit card and auto-loan debt. This debt explosion jeopardizes the fragile recovery, increases the burden on taxpayers and possibly sets the stage for a new economic crisis.

With a still-wobbly jobs market, these loans are increasingly hard to pay off. Unable to find work, many students have returned to school, further driving up their indebtedness.