Like a ticking time bomb, the US national debt is an explosion waiting to happen. It is expanding by about $1.4 billion a day - or nearly $1 million a minute. It breaks down to almost $30,000 in debt for each man, woman, child and infant in the United States. Even those Americans who escaped the recent housing and credit crunches and are coping with rising fuel prices could still be headed for economic misery. That is because the government is fast straining resources needed to meet interest payments on the national debt, which stands at a mind-numbing $9.13 trillion. And like homeowners who took out adjustable-rate mortgages, the government faces the prospect of seeing this debt - now at relatively low interest rates - rolling over to higher rates, multiplying the financial pain.