Click on the image above for the MESSENGER Trajectory Correction Maneuver

Click on the image above for the MESSENGER Trajectory Correction Maneuver

These views of MESSENGER show its orientation for trajectory correction maneuver 15 (TCM-15), which occurred on April 25, 2007. The blue (top view) or dark gray (bottom view) squares represent the front (sunlit) or back (shadowed) sides of the solar arrays, respectively. The large white (top view) or light gray (bottom view) feature is the spacecraft's sunshade, which points toward the Sun when the spacecraft is closer to the Sun than Earth's average distance from the Sun. Colored arrows show the directions of Earth, the Sun, the spacecraft's velocity with respect to the Sun, and each course correction velocity change (ΔV). The "spacecraft +y axis" and "spacecraft +x axis" labels identify axis directions in the spacecraft coordinate system.

The MESSENGER spacecraft's TCM-15 is the second to last course correction required before the second Venus flyby. The next TCM, planned for 25 May 2007, will make small adjustments to direct the spacecraft to the intended aim point above Venus. After TCM-15 and TCM-16, the spacecraft will fly about 337 km (209 miles) above the surface of Venus. Near the time when the spacecraft is closest to Venus, the spacecraft will operate using battery power for about 20 minutes as Venus blocks all sunlight from reaching the solar-powered spacecraft.

A ΔV of 0.568 meters per second (1.86 feet per second) targeted the spacecraft closer to the intended "aim point" above the surface of Venus on June 5, 2007. Mission controllers at The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, verified the start of the maneuver about 10 minutes after the start of TCM-15, when the first signals indicating spacecraft thruster activity reached NASA's Deep Space Network tracking station outside Madrid, Spain. The 140-second duration maneuver began at 1:30 p.m. Eastern Daylight Time.