New spacecraft arrives at Mars

• MAVEN won't land on the surface but study Mars' atmosphere from its orbit


• Why did ancient Mars change so dramatically? MAVEN sent to get answers


• MAVEN stands for Mars Atmosphere and Volatile Evolution craft


• Mars will be having plenty of other visitors: a spacecraft from India and a comet

(CNN) -- MAVEN has arrived in Mars's orbit after traveling 442 million miles in the course of 10 months to get there.

It won't land on the red planet but instead study Mars' atmosphere from above to answer questions about its climate change, NASA says.

NASA's MAVEN craft will live up to its formal name -- the Mars Atmosphere and Volatile Evolution craft -- by helping scientists figure out how ancient Mars changed so dramatically into the planet we know today.

It is the first mission devoted to studying the upper Martian atmosphere as a key to understanding the history of Mars' climate, water and habitability.

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"The evidence shows that the Mars atmosphere today is a cold, dry environment, one where liquid water really can't exist in a stable state," said Bruce Jakosky, MAVEN principal investigator, during a mission preview briefing last week at NASA headquarters in Washington. "But it also tells us when we look at older surfaces, that the ancient surfaces had liquid water flowing over it."

MAVEN to study Mars from above

A new NASA spacecraft called MAVEN, short for Mars Atmosphere and Volatile Evolution, will help scientists figure out what happened to the red planet's atmosphere. It's elliptical orbit will allow it to pass through and sample the entire upper atmosphere of Mars. This drawing shows Maven orbiting Mars.

Is this ancient Mars? An artist shows how Mars might have looked billions of years ago. MAVEN will be the first mission devoted to exploring and understanding the Martian upper atmosphere. Scientists hope it will solve the mystery of the red planet's missing air and water.

Engineers and technicians work on MAVEN at NASA's Kennedy Space Center in Florida. "After 10 years of working on this, I can't tell you how excited I am to see this finished spacecraft ready to go," said the mission's principal investigator, Bruce Jakosky.

Workers on November 2 get MAVEN ready to be placed inside the nosecone that will protect it during launch. NASA says the project will cost $671 million.

A transporter moves MAVEN to the launchpad November 8. MAVEN is NASA's 10th Mars orbiter to be launched. Three didn't make it to orbit.

MAVEN is lifted on top of a rocket for launch. Three other active spacecrafts currently orbit Mars: Mars Odyssey (launched in 2001), Mars Express (launched by the European Space Agency in 2003), and the Mars Reconnaissance Orbiter (launched in 2005).

Reporters and photographers wear protective gear as they get a look at the MAVEN spacecraft. Wingtip to wingtip, MAVEN is the same length of a school bus -- 37.5 feet.

An Atlas V rocket launches MAVEN into space November 18, 2013 from Cape Canaveral Air Force Station, Florida.

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So where did the planet's water and carbon dioxide go?

Jakosky said MAVEN will help unravel that mystery by using its scientific instruments to measure the composition and escape of gases in the Martian atmosphere.

MAVEN is to study the top of the atmosphere to determine the extent to which losing gas to space might have been the driving mechanism behind climate change, Jakosky said.

MAVEN has company out near Mars, man-made and otherwise.

India's first mission to the Red Planet, the Mars Orbiter Mission, is set to arrive a few days after MAVEN does. The director of NASA's Planetary Science Division, Jim Green, says the United States and India are interested in cooperating as their crafts gather data about the planet.

There's a visitor of the cosmic kind, too.

Comet Sliding Spring, which was discovered last year, will be closest to Mars about four weeks after MAVEN arrives.

The comet is going to miss Mars by about 81,000 miles, said Jakosky.

"I'm told that the odds of having an approach that close to Mars are about one-in-a-million years," he said, adding that dust from the comet carries only a "relatively minimal" risk to the spacecraft.

MAVEN will take advantage of the rare flyby by observing the comet itself, as well as its effect on the Martian atmosphere.

Interactive: Exploring Mars from Viking to MAVEN