AUDIE CORNISH, HOST:
Mars has a new visitor from Earth. Last night, NASA's MAVEN spacecraft fired its six main rocket engines for 33 minutes; just enough to slow the probe down so it could be snagged by the red planet's gravitational pull. At a news conference late last night, MAVEN's lead scientist Bruce Jakosky said that the operation went off without a hitch.
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BRUCE JAKOSKY: All I can say, at this point, is we're in orbit at Mars, guys. And we've taken 11 years to get here and now we get to do the science that we've been planning for all this time.
CORNISH: NPR's Joe Palca reports on the mission to study the Martian atmosphere.
JOE PALCA, BYLINE: Mars has a pretty thin atmosphere these days, much of it has been blasted away by a stream of charged particles coming from the sun called the solar wind. Once upon a time, Mars had a magnetic field that shielded it from the solar wind - Earth has such a shield. But sometime in the last few billion years, Mars lost its magnetic field, allowing the solar wind to wreak its havoc. Losing some of its atmosphere probably played a role in turning Mars from the wet planet it once was to the bone-dry planet it is now. MAVEN will study how the solar wind interacts with what's left of the Martian atmosphere today. Scientists will use those measurements to extrapolate back in time to what conditions were like in the planet's watery past. Understanding why the Martian climate changed so dramatically could tell scientists something about climate change here on Earth. There are quite a few science missions operating on and above Mars these days. NASA's rovers Curiosity and Opportunity continue to explore the planet's surface. Mars Odyssey and the Mars Reconnaissance Orbiter are collecting data overhead, as is the European Space Agency's Mars Express. Later this week, an Indian probe is scheduled to join the party. Jim Green is director for Planetary Science at NASA. He says all these science missions are essential if astronauts are to go to Mars someday.
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JIM GREEN: It's really the planetary scientists that are blazing the trail for us to understand everything about Mars that we need to for humans to be able to land safely on Mars and explore and journey around the planet.
PALCA: Sending humans to Mars is still a longs way off - if it ever happens. NASA's next mission to Mars is scheduled for launch in 2016. It's a probe that will land on Mars and study what's going on under the planet's surface. Joe Palca, NPR News. Transcript provided by NPR, Copyright NPR.