"Zero-bound" means "at or near zero." Inflation is easy to kill in today's world: just raise interest rates a little tiny bit for a short period of time and the deflationary downdraft will snuff any little inflationary ticks upward. But they'll be forced to drop rates again quickly or we'll fall back into deflation. The instant they raise rates the debt defaults and asset price collapses will start.

Earth is now Japan. Perhaps Mars is the next America.