Messenger Spacecraft Enters Orbit Around Mercury

NASA's Messenger spacecraft became the first spacecraft to enter orbit around Mercury on Thursday, March 17, 2011.

The Messenger (Mercury Surface, Space, Environment, Geochemistry and Ranging) spacecraft was launched from Cape Canaveral on August 3, 2004 and has been travelling through the inner Solar System since then.  During that time, it has flown past Mercury three times. It has also made two flybys of Venus and one of Earth.

NASA's Mariner 10 is the only other spacecraft that has been sent to observe Mercury.  Between 1974 and 1975, Mariner 10 flew past Mercury three times. However, it was only able to photograph 45% of the planet's surface.

Messenger will be able to provide data about the entire surface of Mercury, as it will be orbiting the planet.

It will have an elliptical orbit that will bring it to about 125 miles (200 kilometers) of the surface at its closest point. It will be more than 9,000 (15,000) miles away when it is furthest from Mercury's surface.

The Messenger spacecraft has been designed to withstand the extreme heat and high levels of radiation that exist around Mercury. However, engineers will be checking the spacecraft's systems for the next few weeks.

According to NASA, science operations are scheduled to begin on April 4.

Scientists hope that data sent by Messenger will help us to learn more about the structure of Mercury and about its environment, which will in turn increase our understanding of how the Solar System was formed.