Just a brief post to announce that at 01:00 UTC MESSENGER completed a 15-minute burn of its main engines to enter orbit at Mercury! According to mission controllers, all indications from the low-rate telemetry received through the spacecraft's low-gain antenna are that the burn proceeded perfectly, just as expected; they are now waiting for the craft to turn to Earth to relay the high-rate telemetry to confirm the details. Regardless of those details, though, MESSENGER is now in Mercury orbit, alive, and communicating with Earth!
We of Earth have now successfully orbited every classical planet -- every body known to move across the heavens and visible to the naked eye. We first orbited Earth in 1957; the Moon in 1966; Mars in 1971; Venus in 1975; Jupiter in 1995; Saturn in 2004; and now, finally, Mercury, in 2011.
The Planetary Society issued a statement this evening congratulating the mission on their success:
"MESSENGER is orbiting Mercury!" said Bill Nye, Executive Director of the Planetary Society. "It's rocket science at its best. Before this success, Mercury was the only inner planet that had never been orbited by a spacecraft."
"MESSENGER's going into orbit is a momentous accomplishment in humanity's quest to explore the solar system," said Bruce Betts, the Planetary Society's Director of Projects. "The mission has already helped us complete humanity's initial reconnaissance of the inner solar system, and provided ground breaking science to help us understand fascinating and exotic Mercury."