From: NASA MESSENGER
Posted: Wednesday, December 7, 2011
The MESSENGER spacecraft successfully completed a fifth orbit-correction maneuver today to lower MESSENGER's periapsis altitude from 442 to 200 kilometers and decrease the orbital period from 12 hours to 11 hours and 47 minutes.
MESSENGER was 102 million kilometers (63.4 million miles) from Earth when the 291-second maneuver began at 11:08 a.m. EST. Mission controllers at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., verified the start of the maneuver about 5 minutes and 40 seconds later, when the first signals indicating spacecraft thruster activity reached NASA's Deep Space Network tracking station outside Goldstone, Calif.
This orbit-correction maneuver, the final one planned for the primary orbital phase of the mission, was executed to keep orbital parameters within desired ranges for optimal scientific observations. MESSENGER's orbital velocity was changed by a total of 22.2 meters per second (49.7 miles per hour) to make the corrections essential for continuing the planned measurement campaigns.
"The successful completion of this burn marks a significant milestone on the MESSENGER project," says MESSENGER Systems Engineer Eric Finnegan of APL. "The propulsion system has now completed all major maneuver requirements for the primary mission. Given the complexity of this propulsion system and the challenges of the trajectory, this is a major achievement for the APL and Aerojet design and mission operation teams."
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