* MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) launched in 2004 and orbited Mercury from 2011 to 2015. It mapped the planet's surface in detail, studied its composition, magnetic field, and thin atmosphere, and even discovered evidence of water ice in permanently shadowed craters at the poles.
While MESSENGER was the only spacecraft to orbit Mercury, there was one earlier mission that flew by the planet:
* Mariner 10 flew by Mercury three times in 1974 and 1975, capturing the first close-up images of the planet. However, it only mapped about 45% of Mercury's surface.
There are currently no active robotic missions to Mercury, but the BepiColombo mission, a joint mission by the European Space Agency and the Japan Aerospace Exploration Agency, is currently on its way to the planet and is expected to arrive in 2025. It will consist of two separate spacecraft:
* Mercury Planetary Orbiter (MPO) will study Mercury's surface, composition, magnetic field, and internal structure.
* Mercury Magnetospheric Orbiter (MMO) will study Mercury's magnetosphere and its interaction with the solar wind.
BepiColombo is expected to provide even more detailed information about Mercury than MESSENGER, potentially revealing new insights into the planet's formation and evolution.
