A day on Mars is 39 minutes longer than a day on Earth.
Working around the clock is tiring enough on Earth. But on Mars, it's even worse.
The martian day, called "Sol", is 39 minutes longer than a day on Earth. For NASA's two robotic rovers, the longer day makes little difference. But for scientists and engineers operating the rover, the longer day becomes a nightmare. NPR's Joe Palca explains why.