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If Santa Were a Martian

side by side images of the Martian North Polar Cap one taken in March 1999 the second taken January 2001
The Martian North Polar Cap

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 presently 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.

Fasten Your Seatbelt

Called the "polar vortex," this cold, low density region forms each winter in the atmosphere above the planet's latitudes 70 degrees north and higher. The region between the polar vortex and the rest of the atmosphere is called the 'transition zone.' In this zone, strong winds swirl around the pole and the zone itself weaves in and out in the typical fashion of a terrestrial jet stream. It is an area where sometimes surprising shifts in the atmospheric density can become fasten-your-seatbelt territory for Odyssey.

"When we're in the transition zone, the atmosphere is very unpredictable," said Smith.

Scientists and engineers have long known that Mars' atmosphere "breathes" -- moving up and down, growing or decreasing in density with the effects of dust storms, winds and other influences. But scientists and navigators are just getting to know up-close the peripatetic polar vortex and its shifty transition zone.

  Aerobraking: It's a Drag >>

Full Text
If Santa Were a Martian
    Aerobraking: It's a Drag
    "Try to Go with the Flow"
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