The Mariner10 space probe and the Mercury Messenger space probe.
Messenger
The messenger space craft was the first to orbit and probe Mercury. The messenger space craft went into orbit in 2011 and is not due to return until 2015.
NASA's MESSENGER probe because it is in orbit around mercury right now.
The MESSENGER probe was launched August 3rd, 2004.
The Mercury Messenger is an orbiting space probe observing the planet Mercury. We generally reserve the word "rover" for a tracked or wheeled vehicle which moves around on the surface, and we haven't tried to do that yet.
No probe has landed on Mercury, however Mariner 10 and Messenger have both surveyed Mercury. Messenger is due to go into orbit around Mercury in 2011 to survey and map the entire planet.
Messenger : (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a space-probe sent to the planet Mercury .
The Messenger probe was launched towards space last August 2004 and it arrived on the orbit of Mercury last March 18, 2011. Its journey towards Mercury took 6 years and 6 months.
There has been only one space probe which [crash] landed on Mercury, and that was Messenger.
Currently the only thing orbiting Mercury is MESSENGER, a space probe built by NASA.
A probe is a tool that is inserted into something to view or get information abour what is going on inside that object. A satellite that goes into deep space is an example of a probe.