Messenger Speeds Past Mercury

NASA's Messenger spacecraft zoomed within 125 miles of Mercury early this morning, making its second successful close approach of the innermost planet since January.

"Things have gone as planned, if not better than planned," said Eric Finnegan, mission systems specialist for the Messenger project at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "Everything went really well."

Launched from Cape Canaveral Air Force Station in 2004, the probe used Mercury's gravity to help push it into position for a third flyby next September.

By March 2011, Messenger is scheduled to become the first spacecraft to orbit the solar system's smallest planet.

Messenger made its closest approach at about 4:40 a.m. today. The scientific observations that make up the second flyby began about 10 hours earlier, and were to continue for another 20 hours.

Messenger scientists and engineers plan to turn the spacecraft toward Earth and begin beaming back data from the flyby at 1:14 a.m. Tuesday. Images should be publicly available around 10 a.m.

During the second flyby, Messenger was to map about 30 percent of the planet - a land area larger than South America - that had never been seen up close by a spacecraft.

In addition to images, scientists also hope to collect data that increases our understanding about the composition of Mercury's surface and the role of volcanic activity in shaping it.

Before Messenger's first pass in January, no spacecraft had visited the planet in more than 30 years. The last close approach was by Mariner 10 in 1975.

A news conference to discuss scientific findings from the second flyby is tentatively set for Oct. 29.

NOTE ON IMAGES: Click the images above to enlarge them.
Above, a false-color image of Mercury, taken with Messenger instruments during the spacecraft's first flyby in January and later published in Science magazine, shows the great Caloris impact basin, visible in this image as a large, circular, orange feature in the center of the picture. Below, the Messenger spacecraft closes in on its second close approach of Mercury. This image, acquired Saturday, appears similar to optical navigation images taken earlier but with the crescent-shaped Mercury growing larger and larger with each additional image set. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington