NASA’s Messenger in place to spy on 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.

After a six-and-a-half year trip, over 4.9 billion miles, NASA’s Messenger spacecraft has successfully fended off the sun and veered into a pinpoint orbit with the planet.

It is the fifth planet in our solar system that NASA has orbited, in addition to the Earth and the moon.

Messenger is in orbit that brings it as close as 120 miles above the planet’s surface. Messenger’s chief engineer, Eric Finnegan, said: “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 also has some of the harshest extremes in the solar system. Temperatures can swing wildly by 800 degrees Celsius.

While it gets up to 425 degrees Celsius on the planet closest to the sun, it is so cold and dark in some craters that the temperatures don’t climb above 184 degrees Celsius below zero. Radars even show that there is likely to be frozen ice in the craters, something Messenger will try to confirm.

In the 1970s, NASA sent a spacecraft, Mariner, past Mercury, but only got pictures of less than half of the tiny rock.

Robert Strom of the University of Arizona was a scientist on the Mariner and current Messenger missions and said he didn’t think he would see the planet again.

“I am just so thrilled it isn’t funny,” Strom said, minutes after NASA confirmed that 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 the approximately 100 million miles from Mercury to Earth.

“This was not easy. This was a very, very difficult manoeuvre to get into orbit,” Strom said.

A NASA Twitter account under Messenger’s name gave play-by-play accounts as it arrived at the small planet. This ‘Messenger’ exchanged tweets with Voyager 2, one of NASA’s oldest and most-distant spacecraft.

Voyager 2, launched in 1977 and now at the edge of the solar system, tweeted good luck and Messenger replied with a tweet: “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 transmitting pictures and investigate Mercury’s mysterious magnetic field and unusual density.

“This is when the real mission begins,” Messenger chief scientist Sean Solomon said an hour after Messenger was safely in Mercury’s orbit. “We are really ready to learn about one of Earth’s nearest neighbours for the first time.”

He said that while Mercury, Venus, Earth and Mars formed at the same time, Mercury “came out very differently”.