US craft to study Martian air

NASA’s latest Mars spacecraft, Maven, arrived Sunday evening to study the mystery of what happened to the planet’s air.

After a 33-minute engine firing, mission controllers received acknowledgment at about 10:25 p.m. Eastern time that Maven was in orbit around Mars.

After a six-week period to turn on and check systems on the spacecraft and to move it to its final orbit, Maven – the name is short for Martian Atmosphere and Volatile Evolution – is to take detailed measurements of the dynamics of Mars’ upper atmosphere.

But first, it will have a sideshow, taking observations of a comet that, by rare happenstance, will make a close flyby of Mars on Oct. 19, passing within 82,000 miles. Mission managers have arranged to activate Maven’s eight scientific sensors by then.

Bruce M. Jakosky, a professor of geological sciences at the University of Colorado who is the mission’s principal investigator, said the spacecraft would spend five days observing how the comet’s dust, traveling at 125,000 mph, might heat up and expand Mars’ atmosphere, and how water ice from the comet might bump up the levels of hydrogen.

As a precaution, Maven will be on the other side of Mars when the shower of comet dust is heaviest. “Just in case there’s any dust that might hit us, we’ll be shielded by the planet,” Jakosky said.

On Monday, he will turn his attention to the coming science measurements. Planetary scientists believe that about 4 billion years ago, Mars was blanketed with a thick layer of air – heat-trapping carbon dioxide, in particular – that kept it warmer and wetter than it is today.