MESSENGER's fifth trajectory correction maneuver lasted just 23 seconds and adjusted its velocity by less than half-a-foot per second. But the fleeting July 21 maneuver went a long way in keeping MESSENGER on track for the upcoming gravity-assist flyby of Earth.
Carried out by two small thrusters that poke through MESSENGER's sunshade, the maneuver pinpointed the craft for a closest approach of 1,458 miles (2,347 kilometers) over central Asia at 3:13 p.m. EDT on Aug. 2. Mission design team members say that directing MESSENGER along just the right path above Earth will mean smaller course-correction maneuvers on the way to the 2006 gravity-assist flyby at Venus - ultimately saving fuel for later in the mission.
Today's maneuver started at 2 p.m. EDT; mission controllers at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, verified the start of the maneuver within 14 seconds, when the first signals indicating spacecraft thruster activity reached NASA's Deep Space Network tracking station outside Madrid, Spain. The spacecraft was 2.6 million miles (4.3 million kilometers) from Earth at the time, speeding around the Sun at 66,738 miles (107,404 kilometers) per hour.
The Earth flyby sends the spacecraft toward Venus; the first of two Venus flybys is planned for October 2006.