The planet Mercury, as seen by departing MESSENGER. MESSENGER (a backronym of MErcury Surface, Space ENvironment, GEochemistry, and Ranging) was a NASA robotic spacecraft that orbited the planet Mercury between 2011 and 2015. The instruments carried by MESSENGER were used on a complex series of flybys - the spacecraft flew by Earth once, Venus twice, and Mercury itself three times, allowing it to decelerate relative to Mercury using minimal fuel. MESSENGER became the second mission after Mariner 10's 1975 flyby to reach Mercury during its first flyby of the planet in January 2008. MESSENGER entered orbit around Mercury on March 18, 2011, becoming the first spacecraft to do so. It successfully completed its primary mission in 2012. Following two mission extensions, the MESSENGER spacecraft used the last of its maneuvering propellant and deorbited as planned, impacting the surface of Mercury on April 30, 2015.