Messenger completes burn to enter Mercury's orbit

NASA's Messenger spacecraft tonight successfully completed a 15-minute engine firing intended to place it in orbit around Mercury.

NASA hasn't yet officially confirmed the orbit was reached, but mission controllers at the Johns Hopkins University's Applied Physics Lab cheered around 9:10 p.m., shortly after the burn was completed.

Messenger would be the first spacecraft to orbit around the solar system's innermost planet.

The spacecraft began its more than six-and-a-half-year, 4.9-million mile journey from Cape Canaveral Air Force Station on Aug. 3, 2004.

The $446-million mission plans to spend a year orbiting the planet, mapping it and investigating its origins, surface composition, dense iron core and magnetic field.

Messenger will orbit Mercury every 12 hours, flying as close as 124 miles and as far as nearly 10,000 miles away.