NASA’s twin Mars rovers Spirit and Opportunity have yielded volumes of new data about the red planet in the last year – the least of which involves the planet’s history of water. But the rovers have also amazed their human handlers with their longevity, lasting nearly four times their initial 90-day mission despite some early glitches that popped up after landing. A new one-hour documentary NOVA: Welcome to Mars (Public Broadcasting System, Jan. 4 at 8:00 p.m.) chronicles the rover mission from the early days after Spirit’s landing through the arrival of Opportunity and some following months.