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Probe whips past Earth on long voyage to Mercury
BY STEPHEN CLARK
SPACEFLIGHT NOW
Posted: August 2, 2005

Earth's first extended visit to the planet Mercury is now one step closer to success after the MESSENGER probe celebrated its birthday one day early on Tuesday with a speedy flyby of its home planet to tweak its course for arrival in orbit in 2011.

MESSENGER made its closest approach to terra firma at 1913 GMT (3:13 p.m. EDT) as it flew 1,458 miles over central Mongolia near the capital of Ulaanbaatar.

In an effort to reduce the amount of propellant MESSENGER had to carry during its launch, engineers designed the mission to include a series of six gravity assist maneuvers past Earth, Venus, and Mercury. These flybys can utilize the force of gravity to alter the future trajectory of the spacecraft, allowing it to swing from planet to planet before eventually entering orbit around Mercury.

"One flyby down, five more to go," said Mark Holdridge, mission operations manager for MESSENGER at the Johns Hopkins University's Applied Physics Laboratory. "Now the mission begins."

Other things happening in space. Contrary to the general appearances, the rest of the space program does not come to a complete halt every time they launch the Space Shuttle.