WASHINGTON — For the first time, Earth has a regular orbiting eye-in-the-sky spying on the solar system’s smallest and strangest planet, Mercury.
NASA’s spacecraft called Messenger successfully veered into a pinpoint orbit last night after a 6 1/2-year trip and 4.9 billion miles and tricky maneuvering to fend off the gravitational pull of the sun. It is the fifth planet in our solar system that NASA has orbited, in addition to Earth and the moon.
“It was right on the money,’’ Messenger’s chief engineer, Eric Finnegan, said. Messenger is in orbit that brings it as close as 120 miles above the planet’s surface.
“Everybody was whooping and hollering; we are elated,’’ he said. “There’s a lot of work left to be done, but we are there.’’
Mercury has some of the most extreme temperatures in the solar system. While it gets up to 800 degrees on the planet closest to the sun, it also is so cold and dark in some craters that the temperatures don’t get above 300 degrees below zero.
In the 1970s, NASA sent a spacecraft, Mariner, whizzing by Mercury, but only got pictures of less than half of the tiny rock.
A NASA Twitter account under Messenger’s name gave play by play. This “Messenger’’ exchanged tweets with Voyager 2, one of NASA’s most-distant spacecraft. Voyager 2 tweeted good luck and Messenger answered with: “Many thanks! Cold out there? Kinda warm where I am.’’ Messenger, which cost NASA $446 million, was launched in 2004. Next month it should start sending pictures.