If Santa Claus were a martian, he’d be in for one bumpy ride. That’s the assessment of navigators and engineers controlling the flight of NASA’s 2001 Mars Odyssey spacecraft as it currently flies four times daily above the north polar region of Mars. “If he were flying above the North Pole of Mars, my advice to Santa would be ‘Hang tight onto your reins,'” said Odyssey navigator John C. Smith. “You could be in for a rough ride.” In the midst of aerobraking maneuvers that are lowering the spacecraft’s orbit around Mars, the Odyssey team has discovered an unexpected and somewhat unpredictable north polar atmospheric disturbance that is making the job a real adventure, Smith said.