From: Johns Hopkins University
Posted: Sunday, November 21, 2004
MESSENGER completed its third trajectory correction maneuver since launch - and its last of 2004 - trimming its speed and tweaking its course toward the Earth flyby next August.
The 48-second burst from MESSENGER's hydrazine-fueled thrusters reduced the spacecraft's velocity by just over 7 miles per hour (3.2 meters per second) relative to the Sun - easing it into a cruising speed of about 62,030 miles (99,827 kilometers) per hour. The maneuver started at 2:30 p.m. EST on Nov. 18; mission operators at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, began tracking it about two minutes later, when the first signals indicating thruster activity reached the NASA Deep Space Network tracking station near Madrid, Spain.
MESSENGER, now nearly 22.8 million miles (36.7 million kilometers) from Earth, is in good health and operating normally. Detailed checkouts of the science instruments and subsystems continue. The solar-powered spacecraft continues to fly with its sunshade away from the sun, allowing it to keep its key systems warm without using power for heaters. Since launch last August 3, MESSENGER's computers have executed more than 15,000 commands from mission control.
Visit the Mission Design section (http://messenger.jhuapl.edu/the_mission/mission_design.html#tcm ) of the MESSENGER Web site for graphics and more details on the latest trajectory correction maneuver. The next "TCM" is tentatively planned for March 10, 2005.
MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a scientific investigation of the planet Mercury, and the first NASA mission designed to orbit the planet closest to the Sun. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as principal investigator. The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, built and operates the MESSENGER spacecraft and manages the Discovery-class mission for NASA.
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