It's showtime at Mars.

NASA's Maven spacecraft is on track to reach the red planet late Sunday night following a journey spanning 10 months and 442 million miles.

If all goes well, the robotic explorer will slip into Martian orbit for a year or more of atmospheric study. It's designed to circle the planet, not land.

Maven will be the first spacecraft to focus on the upper atmosphere of Mars. 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.

The $671 million mission began with a launch from Cape Canaveral last November.