MESSENGER Mission News December 19, 2007

MESSENGER’s nineteenth trajectory-correction maneuver (TCM-19) completed on December 19 lasted 110 seconds and adjusted the spacecraft’s velocity by 1.1 meters per second (3.6 feet per second). The movement targeted the spacecraft close to the intended aim point 200 km (124 miles) above the night-side surface of Mercury for the probe’s first flyby of that planet on January 14, 2008.

The maneuver started at 5:00 p.m. EDT. Mission controllers at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., verified the start of TCM-19 about 13 minutes later, after the first signals indicating thruster activity reached NASA’s Deep Space Network tracking station outside Canberra, Australia.

“The MESSENGER spacecraft’s TCM-19 is one in a series of potential course correction opportunities planned in advance of the first Mercury flyby,” explained APL’s Eric Finnegan, MESSENGER’s Mission Systems Engineer. “TCM-19 corrected small deviations in the trajectory remaining after the successful execution of the deep-space maneuver on October 18.”

“We’re now set for our flyby,” added MESSENGER Principal Investigator Sean Solomon. “Achieving our aim point not only will give us our first close-up view of Mercury in nearly 33 years; it will ensure that we continue on the trajectory needed to place, for the first time, a spacecraft into orbit around the innermost planet three years later.”

For graphics of MESSENGER’s orientation during the maneuver, visit the “Trajectory Correction Maneuvers” section of the mission Web site at http://messenger/the_mission/maneuvers.html .

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.