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Most Recent Trajectory Correction Maneuver

This view of MESSENGER shows the orientation soon after the start of orbit correction maneuver 9 (OCM-9). The blue squares represent the front (sunlit) sides of the solar arrays. The large white feature is the spacecraft's sunshade, which points toward the Sun when the spacecraft is near or closer than Earth's distance from the Sun. Colored arrows indicate the directions of Earth, the Sun, the spacecraft's velocity with respect to Mercury, and the course-correction velocity change (delta-V or ΔV). The "spacecraft +x axis" label identifies an axis direction in the local spacecraft body-fixed coordinate system.

The ninth OCM since Mercury orbit insertion, OCM-9 raised the spacecraft’s minimum altitude above Mercury from 113.9 km (70.8 miles) to 155.1 km (96.4 miles). During OCM-9, a ΔV of 5.03 meters per second (11.25 miles per hour) was imparted using two of the four largest monopropellant thrusters, with a small contribution from four of the 12 smallest monopropellant thrusters. Implemented when the spacecraft was at the farthest point in its orbit from Mercury, OCM-9 increased the spacecraft’s speed relative to Mercury. OCM-9 also added about two minutes to the spacecraft’s 8-hr orbit period. During OCM-9, the sunshade protected heat-sensitive parts from direct sunlight.  OCM-9 was the first orbit correction maneuver of MESSENGER’s second extended mission. The next three OCMs, scheduled on September 12, 2014, October 24, 2014, and January 21, 2015, will also raise the spacecraft’s minimum altitude.

Mission controllers at The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, verified the start of the maneuver about 4.6 minutes after the start of OCM-9 during the morning on June 17, 2014, when the first signals indicating spacecraft thruster activity will reach NASA's Deep Space Network (DSN) tracking station outside of Madrid, Spain. The 3.2-minute-long maneuver began at about 10:53 am Eastern Daylight Time.

Click here for detailed information on all of MESSENGER’s propulsive activity from launch to the present.



the orientation at the start of orbit correction maneuver 9 (OCM-9)
Click on the image above for a larger version

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