Messenger To Mercury
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 Messenger successfully veered into a pinpoint orbit on Thursday night after a 6½-year trip and almost 8 billion kilometres and tricky manoeuvering 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 an orbit that brings it to within 193 kilometres of the planet’s surface. “This is as close as you can possibly get to being perfect.”
“Everybody was whooping and hollering; we are elated,” Finnegan said. “There’s a lot of work left to be done, but we are there.”
Mercury is not only difficult to get to, but it has some of the most extremes in the solar system. Temperatures swing wildly by 600 degrees. While it gets up to 425 degrees on the planet closest to the sun, it also is so cold and dark in some craters that temperatures don’t get above 184 degrees below zero. Radar even shows there is most likely frozen ice in those craters, something Messenger will try to confirm.
In the 1970s, NASA sent the Mariner spacecraft whizzing by Mercury, but only obtained pictures of less than half of the tiny rock.
Robert Strom of the University of Arizona was a scientist on Mariner and current Messenger missions and he said, for a while, he thought he wouldn’t get a second peek at the eccentric Mercury.
“I am just so thrilled, it isn’t funny,” Strom said by telephone, minutes after NASA confirmed Messenger was in orbit. “Thirty-six years waiting for this day. It’s just unbelievable.”
Strom said he and all his colleagues were nervous as the desk-sized spacecraft automatically shifted into an egg-shaped orbit, with controllers on Earth unable to change commands because it took eight minutes for signals to travel about 160 million kilometres from Mercury to Earth.
“This was not easy. This was a very, very difficult manoeuvre to get into orbit,” Strom told The Associated Press.
Messenger was launched in 2004. Next month, it should start transmitting pictures and investigate Mercury’s mysterious magnetic field and unusual density.