06.06.2007
The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft swung by Venus for the second time early on June 5th for a gravity assist that shrank the radius of its orbit around the Sun, pulling it closer to Mercury. At nearly 15,000 miles per hour, this change in MESSENGER's velocity is the largest of the mission.
Mission operators at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, MD, said MESSENGER's systems performed flawlessly as the spacecraft sped over the cloud tops of Venus at a relative velocity of more than 30,000 miles per hour, passing within 200 miles of the surface of the planet at 23:08 UTC (7:08 p.m. EDT).
For 20 minutes during this closest approach, MESSENGER was within the shadow of Venus. In the absence of solar power, the probe relied solely on its internal battery. By 1:32 UTC (9:32 p.m. EDT) the battery had fully recharged, and the spacecraft was operating as planned. "The biggest milestone for mission operations was first acquisition of telemetry following closest approach, and confirmation that the battery was fully recharged following the 20-minute solar eclipse," said APL's Andy Calloway, MESSENGER's mission operations manager. "We will be monitoring recorder playback beginning June 7 to make sure all of the files and images are fully downlinked.
"This second Venus flyby was a critical milestone in MESSENGER's circuitous journey toward Mercury orbit insertion," said principal investigator Sean Solomon from the Carnegie Institution of Washington. "Not only did the maneuver sharpen the spacecraft's aim toward the first encounter with Mercury in more than three decades, it presented a special opportunity to calibrate several of our science instruments and learn something new about Earth's nearest neighbor." On January 14, 2008, the spacecraft carry out the first flyby of Mercury in 33 years.
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