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Most Recent Trajectory Correction Maneuver

This view of MESSENGER shows the orientation soon after the start of orbit correction maneuver 10 (OCM-10). The blue rectangles 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. Above and to the left of the MESSENGER spacecraft is a portion of Mercury’s southern hemisphere, with latitude lines at 15° increments and longitude lines at 30° increments. The curved purple line depicts MESSENGER’s orbit about Mercury.

The tenth OCM since Mercury orbit insertion, OCM-10 raised the spacecraft’s minimum altitude above Mercury from 24.3 km (15.1 miles) to 94.0 km (58.4 miles). During OCM-10, a ΔV of 8.57 meters per second (19.17 miles per hour) was imparted by 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-10 increased the spacecraft’s speed relative to Mercury. OCM-10 also added about 3.2 minutes to the spacecraft’s 8h 2m orbit period. During OCM-10, the sunshade protected heat-sensitive parts from direct sunlight. OCM-10 was the last orbit correction maneuver that drew propellant from either of the spacecraft’s two main fuel tanks. All future OCMs, which will also raise the spacecraft’s minimum altitude, will draw propellant from a small auxiliary fuel tank.

Mission controllers at The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, verified the start of the maneuver about 9.2 minutes after the start of OCM-10, shortly after noon on September 12, 2014, when the first signals indicating spacecraft thruster activity reached NASA's Deep Space Network (DSN) tracking station outside of Madrid, Spain. The 2.25-minute-long maneuver began at about 11:54 am Eastern Daylight Time.

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



the orientation soon after the start of orbit correction maneuver 10 (OCM-10)
Click on the image above for a larger version

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