NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has entered orbit around Mars for an unprecedented study of the planets atmosphere following a 710 million kilometer journey that began nearly a year ago.

The spacecraft entered into orbit around Mars late on Sunday night.

NASA's Maven was clocking more than 16,000 million kph when it hit the brakes for the so-called orbital insertion, a half-hour process.

The world had to wait 12 minutes to learn the outcome, once it occurred, because of the lag in spacecraft signals given the 222 million kilometres between the two planets.

"I think my heart is about ready to start again," Maven's chief investigator, Bruce Jakosky of the University of Colorado, said on Monday. 

The 671 million dollar mission is dedicated to studying the Martian upper atmosphere with no intention of landing.

The explorer will be monitored by flight controllers in Colorado, while they adjust Maven's altitude and constantly check its science instruments.

Flight controllers will also focus on observing a comet streaking by a relatively close range.

Scientists believe the Martian atmosphere holds clues to how Earth's neighbour went from being warm and wet billions of years ago to cold and dry.

Jakosky hopes to learn where all the water on Mars went, along with the carbon dioxide that once comprised an atmosphere thick enough to hold moist clouds.

The gases may have been stripped away by the sun early in Mars' existence, escaping into the upper atmosphere and out into space. Maven's observations should be able to extrapolate back in time, Jakosky said.

Maven joins three different spacecrafts already circling Mars, two American and one European in addition to India's first interplanetary probe, Mangalyaan.

The spacecraft will spend at least a year collecting data, which is equivilent to half a martian one.

Its orbit will dip as low as 125 kilometres above the Martian surface as its eight instruments make measurements. The craft is as long as a school bus, from solar wingtip to tip, and as hefty as an SUV.

Three previous missions have failed, until the official word came of success late Sunday night, the entire team was on edge.

Lockheed Martin Corp., Maven's maker, is operating the mission from its control center at Littleton, Colorado.

This is NASA's 21st shot at Mars and the first since the Curiosity rover landed on the red planet in 2012, more landers are expected in 2016 and 2018 from NASA and the European and Russian space agencies.

Source: AP