CAPE CANAVERAL, Fla. (AP) — NASA's Maven spacecraft entered orbit around Mars for an unprecedented study of the red planet's atmosphere following a 442 million-mile journey that began nearly a year ago. 
  
 The robotic explorer successfully slipped into orbit around the red planet late Sunday night. 
  
 "I think my heart's about ready to start again," Maven's chief investigator, Bruce Jakosky of the University of Colorado, said early Monday. "All I can say at this point is, 'We're in orbit at Mars, guys!'" 
  
 Now the real work begins for the $671 million mission, the first dedicated to studying the Martian upper atmosphere and the latest step in NASA's bid to send astronauts to Mars in the 2030s. 
  
 Flight controllers in Colorado will spend the next six weeks adjusting Maven's altitude and checking its science instruments, and observing a comet streaking by at relatively close range. Then in early November, Maven will start probing the upper atmosphere of Mars. The spacecraft will conduct its observations from orbit; it's not meant to land. 
  
 Scientists believe the Martian atmosphere holds clues as to how Earth's neighbor went from being warm and wet billions of years ago to cold and dry. That early wet world may have harbored microbial life, a tantalizing question yet to be answered. 
  
 NASA launched Maven last November from Cape Canaveral, the 10th U.S. mission sent to orbit the red planet. Three earlier ones failed, and until the official word came of success late Sunday night, the entire team was on edge. 
  
 "I don't have any fingernails any more, but we've made it," said Colleen Hartman, deputy director for science at Goddard Space Flight Center in Greenbelt, Maryland. "It's incredible." 
  
 The spacecraft was clocking more than 10,000 mph 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 138 million miles between the two planets Sunday. 
  
 "Wow, what a night. You get one shot with Mars orbit insertion, and Maven nailed it tonight," said NASA project manager David Mitchell. 
  
 Maven joins three spacecraft already circling Mars, two American and one European. And the traffic jam isn't over: India's first interplanetary probe, Mangalyaan, will reach Mars in two days and also aim for orbit. Jakosky wished the team well. 
  
 Jakosky, who's with the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder, 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 — short for Mars Atmosphere and Volatile Evolution Mission — will spend at least a year collecting data. That's a full Earth year, half a Martian one. Its orbit will dip as low as 78 miles 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. 
  
 Maven will have a rare brush with a comet next month. 
  
 The nucleus of newly discovered Comet Siding Spring will pass 82,000 miles from Mars on Oct. 19. The risk of comet dust damaging Maven is low, officials said, and the spacecraft should be able to observe Siding Spring as a science bonus. 
  
 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. Just this month, Curiosity arrived at its prime science target, a mountain named Sharp, ripe for drilling. The Opportunity rover is also still active a decade after landing. 
  
 More landers will be on the way in 2016 and 2018 from NASA and the European and Russian space agencies. The next U.S. rover is scheduled for launch in 2020; more capable than Curiosity, it will collect samples for possible return to Earth, and attempt to produce oxygen from atmospheric carbon dioxide. That latter experiment, if successful, would allow future human explorers to live off the land, according to NASA's John Grunsfeld, head of science missions and a former astronaut. 
  
 "This really is a quest of humanity," he said. 
  
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 Online: 
  
 NASA: http://mars.nasa.gov/maven/ 
  
 University of Colorado: http://lasp.colorado.edu/home/maven/ ||||| Mars has welcomed a new robotic visitor from Earth. 
  
 After a 10-month journey through deep space, NASA's MAVEN probe arrived in Mars orbit late Sunday (Sept. 21), on a mission to help scientists figure out why the Red Planet changed from a relatively warm and wet place in the ancient past to the cold, arid world it is today. 
  
 MAVEN, whose name is short for Mars Atmosphere and Volatile Evolution, fired its engines in a crucial 30-minute braking burn Sunday night, slowing down enough to be captured by the planet's gravity around 10:24 p.m. EDT (0224 GMT Monday, Sept. 22). [See images from the MAVEN mission] 
  
 "Congratulations! MAVEN is now in Mars orbit," MAVEN navigation team member Dave Folta, of NASA's Goddard Space Flight Center in Greenbelt, Maryland, announced to a round of cheers from mission control. 
  
 MAVEN joins three other operational probes in Mars orbit — NASA's Mars Odyssey spacecraft and Mars Reconnaissance Orbiter (MRO), and the European Space Agency's Mars Express. NASA also has two rovers actively exploring the planet's surface: the golf-cart-size Opportunity and its younger, bigger cousin, Curiosity. 
  
 And Mars orbit should get even more crowded just a few days from now. India's first-ever Red Planet effort, the $74 million Mars Orbiter Mission, is due to arrive Tuesday night (Sept. 23). 
  
 Maven will orbit Mars, looking for clues about what happened to the planet's once-thick atmosphere. Credit: by Karl Tate, Infographics Artist 
  
 The $671 million MAVEN mission blasted off as planned on Nov. 18, 2013, though not without a bit of prelaunch drama. 
  
 Liftoff preparations were frozen when the government shutdown went into effect on Oct. 1, 2013, sending ripples of anxiety through the MAVEN team and the global planetary science community. But NASA granted MAVEN an emergency exception a few days later, getting things back on track. (The shutdown ended on Oct. 17, 2013.) 
  
 MAVEN is the first NASA spacecraft dedicated to studying the upper atmosphere of Mars, NASA officials said. The mission will use MAVEN's three suites of scientific instruments to measure and characterize gas escape from the Martian atmosphere, which was once relatively thick but is now just 1 percent as dense as that of Earth at sea level. 
  
 MAVEN's observations should help scientists get a better handle on what happened to the water that flowed and sloshed across Mars billions of years ago — whether it escaped into space or sank into the planet's crust, said mission principal investigator Bruce Jakosky, of the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. [7 Biggest Mysteries of Mars] 
  
 "What we're going to be doing is studying the top of the atmosphere as a way of understanding the extent to which stripping of gas out of the atmosphere to space may have been the driving mechanism behind climate change," Jakosky said at a news conference Wednesday (Sept. 17). "We should be able to get enough measurements to tell us what happened to the water, what happened to the carbon dioxide." 
  
 The mission should shed light on the history of Mars' ability to support life, he added. 
  
 "We're trying to understand the context in which life might have existed," Jakosky said. "Any life on Mars interacts with its planetary environment; we need to know what that environment is, and how it's evolved over time." 
  
 MAVEN's prime science mission is slated to last one year, but the probe has enough fuel to keep making observations for a while if its mission gets extended, team members said. 
  
 MAVEN will also serve as a vital communications link between ground controllers and NASA's Mars rovers. In fact, that's the main reason NASA deemed the mission worthy of an emergency exception during the government shutdown. Opportunity and Curiosity are currently supported by Mars Odyssey and MRO, which launched in 2001 and 2005, respectively, and NASA has no Red Planet relay orbiters on the books beyond MAVEN. 
  
 "MAVEN is critically important for us for many reasons, not the least of which is it will serve as backup communications for the rovers on the surface," NASA Administrator Charles Bolden told Space.com. 
  
 MAVEN is one of several missions that should help NASA prepare for an eventual manned mission to Mars, which the agency hopes to mount by the mid-2030s, Bolden added. That mission list includes the active rovers and orbiters now studying Mars, MAVEN and the agency's Mars Insight mission, set to launch in 2016, and the Mars Rover 2020 mission. 
  
 No planet is more steeped in myth and misconception than Mars. This quiz will reveal how much you really know about some of the goofiest claims about the red planet. Start the Quiz 0 of 10 questions complete 
  
 Mars Myths & Misconceptions: Quiz No planet is more steeped in myth and misconception than Mars. This quiz will reveal how much you really know about some of the goofiest claims about the red planet. 0 of questions complete 
  
 MAVEN's science mission will not start right away. The probe's handlers will spend the next six weeks checking out MAVEN's instruments and maneuvering the probe from its long, looping initial orbit down to a 4.5-hour final orbit, which will bring MAVEN as close as 93 miles (150 kilometers) to Mars and take it as far away as 3,850 miles (6,200 km) from the Red Planet. 
  
 But MAVEN will make some observations during this checkout period: The probe will look on as Comet Siding Spring buzzes Mars on Oct. 19, coming within just 82,000 miles (132,000 km) of the planet. (For reference, Earth's moon orbits at an average distance of 238,900 miles, or 384,400 km). 
  
 "I'm told that the odds of having an approach that close to Mars are about one in a million years," Jakosky said. "So it's really luck that we get the opportunity here." 
  
 MAVEN will study the comet and Mars' upper atmosphere for five days around the flyby, he added. 
  
 "We should learn a lot about the upper atmosphere from this natural experiment, watching the perturbation from the impact of [cometary] gas and dust," Jakosky said. "And we're hoping to learn about the comet as well." 
  
 Any material potentially shed by Siding Spring poses minimal risk to MAVEN and other probes circling the Red Planet, NASA officials have said. There are no worries at all for Opportunity and Curiosity, who enjoy the protection of Mars' atmosphere. 
  
 Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com. |||||

Write a summary.
– After 442 million miles and a year on the space road, Maven has finally reached its destination. The NASA spacecraft successfully completed a harrowing 30-minute "orbital insertion" into Mars' orbit last night, the AP reports. "I don't have any fingernails any more, but we've made it," says the deputy director for science at Goddard Space Flight Center in Greenbelt, Md. Scientists have big plans for the explorer: It's going to be the first mission to study the Martian upper atmosphere from orbit—it's not meant to land on the surface—in advance of NASA's ambitious plans to send astronauts to Mars in the 2030s. Maven isn't the only new addition to the Martian skies: As Space.com notes, India's Mars Orbiter Mission is set to arrive on the scene tomorrow night. Researchers believe Mars used to be a "warm and wet" planet billions of years ago and that it may have even sustained microbial life, but they're not sure what sucked all of the water off the planet's surface and eliminated carbon dioxide from its atmosphere (one theory is the sun stripped the planet clean). The school-bus-sized Maven—short for Mars Atmosphere and Volatile Evolution Mission—will spend at least a year hovering as low as 78 miles over the planet's surface, using eight high-tech instruments to gather info and even observe the Siding Spring comet that's set to zip by on Oct. 19. Meanwhile, Curiosity and another rover set to launch in 2020 are designed to bring Mars samples back to Earth and try to make oxygen out of carbon dioxide—a process that would help human explorers survive on Mars, the AP notes. "This really is a quest of humanity," NASA's head of science missions says.