"And now we get to do the science that we’ve been planning for all this time,” said Bruce M. Jakosky, the mission’s principal investigator, who came up with the concept for Maven 11 years ago.

The mission team will spend six weeks turning on and checking systems on Maven — the name is short for Martian Atmosphere and Volatile Evolution — and moving it to its final 4.5-hour orbit before beginning its science measurements in November.

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.

The spacecraft is to spend five days observing how the comet’s dust, traveling at 125,000 miles per hour, 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, using it as a shield, when the shower of comet dust is heaviest.