At 2:04 p.m. EST on Jan. 14, 2008, the MESSENGER spacecraft skimmed 200 kilometers (124 miles) above the surface of Mercury in the first of three flybys of the planet. Initial indications from the radio signals indicate the spacecraft is still operating nominally. The first science data return from the flyby was received just minutes before the closest approach point with the planet, as planned.

“The engineers and operators at the Deep Space Network (DSN) in Goldstone, Calif., in conjunction with engineers at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., pulled off a tremendous feat, acquiring and locking onto the downlink signal from the spacecraft within seconds, providing the necessary Doppler measurements for the Radio Science team” said MESSENGER Mission Systems Engineer Eric Finnegan, of APL.“ The spacecraft is continuing to collect imagery and other scientific measurements from the planet as we now depart Mercury from the illuminated side, documenting for the first time the previously unseen surface of the planet.”

Tomorrow at noon EST, the spacecraft will turn back towards the Earth to start down-linking the on-board stored data. Measurements of this Doppler signal from the spacecraft will allow improve knowledge of Mercury’s gravity field.

Keeping a Rendezvous with Mercury

Between January 9 and 13, 2008, as the MESSENGER probe approached Mercury for its first flyby, the Narrow Angle Camera, part of the Mercury Dual Imaging System (MDIS), acquired a series of images of the planet in support of spacecraft navigation. These images have been put together as frames in a movie. The final frame of the movie has the highest spatial resolution (20 km/pixel, 12 miles/pixel) and was recorded when the spacecraft was at a distance of about 760,000 kilometers (470,000 miles) from Mercury. Mercury is about 4.880 kilometers (about 3,030 miles) in diameter.

As part of MESSENGER's flyby on January 14, MDIS will obtain high-resolution image sequences with the Narrow Angle Camera, and the Wide Angle Camera will collect images in eleven colors. The images will cover portions of the planet never before seen by spacecraft, as well as regions that were photographed by Mariner 10 in 1974 and 1975. The new data for the previously studied areas of Mercury will help scientists to interpret the data for the parts of the planet that MESSENGER will reveal for the first time.

Additional information and features from this first flyby can be viewed online at http://messenger.jhuapl.edu/mer_flyby1.html. The latest released images and science results from the flyby will be posted as they become available.

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as principal investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.