Messenger spacecraft to enter the Mercury's orbit

Its been a six-year ride through space but NASAs Messenger spacecraft is expected to reach Mercurys orbit on Thursday.Not much larger than a refrigerator, Messenger was launched in 2006 and has made 15 loops around the sun en route to Mercury. It will be the second spacecraft to reach Mercury since NASAs Mariner 10 visited the 1975.Some of the tools on board Messenger include a: magnetometer, a camera and four spectrometers. Mercury is the smallest of the solar systems rocky planets and is significantly closer to the sun than earth.Messenger will spend a year orbiting the planet and gathering new images of Mercury.