WASHINGTON -- A dusty welcome mat is out for NASA's Mars Odyssey spacecraft, now less than two weeks away from dropping into orbit around the red planet.

A global dust storm of massive proportions, unlike any seen since the early 1970s, now rages across Mars. The already on-duty spacecraft, Mars Global Surveyor, as well as the Earth-orbiting Hubble Space Telescope, are giving scientists front row seats to the churning storm.

Mars' Perfect Storm

A Dust Storm Engulfs Mars This MGS animation depicts the pace of the spread of the global dust storm on Mars. Beginning in the Hellas Basin in May of this year, the storm gathered in intensity and spread north and east. The storm eventually swallows the planet.

MGS Spies a Martian Dust Storm This animation represents atmospheric data from the Mars Global Surveyor's Thermal Emission Spectrograph. As the dust clouds grow thicker, they absorb more warmth from the sun and raising the temperature of the atmosphere.

At a NASA briefing on October 11, scientists offered their views on what they call the "perfect storm" on the planet. Mars weather watching is even more critical because the soon-to-arrive Odyssey spacecraft must repeatedly dip into the Martian atmosphere to move itself into a correct orbit for carrying out science duties.

For the past three months, Mars has been blanketed by a dust storm, larger by far, than any seen on Earth.

Dust particles tossed high above the surface are being warmed by the Sun. They in turn heat up Mars' thin and mostly carbon dioxide-laden atmosphere.

This abrupt onset of global warming is taking place at the same time as Mars' surface has chilled precipitously under the looming and large shroud of dust.

A puzzle for scientists is what triggers local dust storm events that then kick off separate storms thousands of miles away.

The good news is that the planet-wide storm is beginning to weaken.

On the other hand, scientists expect a "one-two punch" on the planet - stirred up as Mars moves to the closest point of its orbit to the Sun. With the planet's atmosphere is clearing, the return of unfiltered solar radiation is likely to touch off additional high winds and kick up the dust all over again. This is a pattern that has been seen on Mars throughout observational history.

"This is a very exciting time in history," said James Garvin, Mars Exploration Program Lead Scientist at NASA Headquarters. Having the ability to monitor weather happenings on Mars with both the Hubble Space Telescope and on-the-spot looks by Mars Global Surveyor is yielding a spectacular data set, he said.

Garvin said that the Mars storm planted here on Earth would create cataclysmic consequences. Material whipped up high over Mars is a resulting condition somewhat akin to what took place on our planet when an impacting comet or asteroid is thought to have taken out the dinosaurs. Sun-blocking dust threw Earth into a chilling and photosynthesis-breaking chain of events, supposedly ending the rein of the big beasts.

"This is the largest meteorological event that's occurred on Mars since we've started observing with the Hubble Space Telescope," said James Bell, an astronomer at Cornell University in Ithaca, New York. "There is a veil of hazy reddish dust. It's what astronomers call planet encircling," he said.

An instrument on the Mars Global Surveyor -- the Thermal Emission Spectrometer -- has been eyeing the blooming dust storm, said Philip Christensen of Arizona State University in Tempe. He is principal investigator for the infrared device that can penetrate the upwelling dust, yielding data on temperature of the particles, how much dust is airborne, and the whereabouts of the suspended particles.

Christensen said that the dust storms actually spawn other storms. "We see a Mars that's closely balanced," he said, in terms of some type of critical threshold that is crossed that seems to unleash dust storms.

Engineers operating the en route Mars Odyssey spacecraft are closely watching the storm. A rendezvous with Mars by the probe comes later this month. Once Odyssey inserts itself into a large, looping orbit around the planet, the vehicle must then "toe-dip" its way into the Martian atmosphere in a series of aerobraking maneuvers.

Digging in too deep into a dust-filled upper atmosphere could mean damaging the spacecraft. Odyssey could, literally, bite the dust. Too shallow, then the probe won't get into the right orbit to do science in a timely fashion.

"Fortunately, we have Mars Global Surveyor operating. It's able to monitor the atmosphere on a daily basisso that we're not caught unaware," said Richard Zurek, an atmospheric expert at Jet Propulsion Laboratory (JPL) in Pasadena, California. Knowing the various densities of the Martian atmosphere, and at what altitudes they occur, is a service that Mars Global Surveyor is providing, he said.

Camera gear onboard Mars Global Surveyor has helped chart the billowing dust storms. "We see where the wind blows into the atmosphere to form plumes," said Michael Malin of Malin Space Science Systems, Inc., in San Diego, California.

As principal investigator for the Surveyor's camera, Malin said that snapping high-resolution imagery of the Martian surface had to be suspended due to the obscuring dust. "Now that it's clearing, we'll start taking pictures again next week," he told SPACE.com.

"What this dust storm shows is that Martian meteorology is important," Malin said. In the future, if human expeditions are to explore Mars, some type of operational weather satellite system around the red planet would allow accurate forecasting of evolving dust storms, he said.

"Things that happen on one part of the planet can effect you a long way away. That's the message," Zurek added.

This is not the first time an arriving Mars craft has encountered a blustery Martian dust storm.

Back in November 1971, the U.S. Mariner 9 probe played a hide-and-seek game with Mars. It had to wait out a violent dust storm for months before onboard cameras could clearly image the planet's surface.

But two Russian landing probes in the same time period weren't so lucky. They were ejected from their respective orbiters, plunging headlong into the dust storm. A Mars 2 capsule went on the blink before it landed. A Mars 3 lander did start relaying data after touchdown, but ceased working after some 20 seconds. While hardware problems could have cut short the lives of the robots, the turbulent Martian atmosphere is believed to have been reason for their demise.

Meanwhile, fingers are crossed for Mars Odyssey as it nears its target.

"At this point, it's down to where luck plays a role," said Steve Saunders, Mars Odyssey Project Scientist at JPL. "We've done everything that we can do. But you can't rule out bad luck. I don't expect itwe've done everything possible," he told SPACE.com.