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For a mission to Mars, it's got a distinctly unsexy name - MAVEN. It doesn't help at all to tell you that that stands for Mars Atmosphere and Volatile Evolution. But the probe, which should reach the red planet later tonight, is on a mission of vital interest to anyone who enjoys living on earth. NPR's Joe Palca explains.
JOE PALCA, BYLINE: You can describe the point of the MAVEN mission in one simple sentence.
BRUCE JAKOSKY: The MAVEN mission is about understanding the history of the climate on Mars.
PALCA: That the Bruce Jakosky of the University of Colorado in Boulder. At a news conference last week, Jakosky explained that something happened in the past few billion years or so that changed the climate on Mars dramatically. He says when you look at aerial pictures of the Martian surface, you see unmistakable signs that Mars was once upon a time a fairly wet planet.
JAKOSKY: We see evidence for lakes, for river channels, a lot of evidence for liquid water that required a very different climate than the one we have today.
PALCA: Because today, the surface of Mars is bone dry. So the question is, where did the water go? Jakosky says there are basically only two possibilities. One, it could've sunk into the ground. Or two, it could have evaporated and gone up into the atmosphere. MAVEN will study option number two.
JAKOSKY: We're going to be exploring an aspect of the Martian atmosphere and upper atmosphere that really has not been explored in detail by any spacecraft to date.
PALCA: There's not much left of the Martian atmosphere these days. Scientists think a stream of charged particles coming from the Sun, called the solar wind, is largely responsible for knocking a lot of the atmosphere, including water vapor, out into space.
Earth's atmosphere is also blasted by the solar wind. But Earth's magnetic field deflects most of the particles in the wind around the Earth. It seems Mars also once had a magnetic field protecting it. But sometime in the past few billion years, that magnetic field went away - probably because the planet's core solidified. Without that shield, the solar wind was free to do its damage.
Jakosky says MAVEN will study how the solar wind and other factors are affecting the planet's atmosphere today.
JAKOSKY: We measure these things today, even though the processes we're interested in operated billions of years ago. By looking today, we can understand the processes and how they operated and extrapolate backwards in time.
PALCA: And that understanding could help explain how major climate changes can occur here on Earth as well. This is a big night for Bruce Jakosky. He's been working on this mission for more than a decade. But before MAVEN can make its measurements, its rockets have to fire on time and for the right length of time. Guy Beutelschies is MAVEN program manager for Lockheed Martin, the company that built the spacecraft. He says mission managers have already sent the spacecraft its rocket firing sequence.
GUY BEUTELSCHIES: The commands will execute according to the onboard clock. So there's actually nothing that the team needs to do. The spacecraft will execute all of those on its own.
PALCA: Even though the rockets are set to start firing at 9:37 tonight, mission managers won't know right away if that happened.
BEUTELSCHIES: Keep in mind it takes 12 1/2 minutes for the radio signals to travel all the way from Mars to the Earth. So we won't actually see the start of the burn until approximately 9:50.
PALCA: The rocket burn should put MAVEN into an orbit that will take it 35 hours to make one revolution around Mars. BEUTELSCHIES says scientists ultimately want a much shorter orbit - about 4.5 hours. But he says several more rocket firings are necessary to achieve that.
BEUTELSCHIES: It'll be a six-week period where we will be getting the spacecraft all configured and ready to start science mapping.
PALCA: And then Bruce Jakosky can start getting the data from the Martian atmosphere he's been waiting more than a decade for. Joe Palca, NPR News.
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