Mariner 10 was only able to photograph around half of Mercury's surface. For almost than 30 years, no spacecraft has visited Mercury. Then, in 2008 and 2009, NASA's MESSENGER spacecraft sailed by Mercury. It began its orbit around Mercury on March 17, 2011. MESSENGER is the first ever space mission to orbit another planet. Its goal is to study how planets form and evolve over time. Since its launch in 2004, MESSENGER has been traveling at about 57,000 miles per hour (93,000 kilometers per hour) as it orbits around our star. Each day, it takes about 94 million miles (150 million kilometers) to complete one orbit. That's about half the distance from Earth to the Moon but four times farther from the Sun than we are. At its current distance of about 37 million miles (60 million kilometers), it will take MESSENGER three months to reach Mercury and one month to return to Earth. As it passes by, the probe will be able to tell us more about the innermost planet than anyone has ever done before. NASA launched MESSENGER on a Mercury mission in April 2004. The agency developed the spacecraft with industry partners, including Thales Alenia Space, which built the main body and science platform. French company Astrium made the solar panels that power the vehicle.