mercury
no robots have roamed Mercury
yes, MESSENGER has explored Mercury. On March 18, 2011 a year from today, MESSENGER will transition from orbiting the Sun to being the first spacecraft ever to orbit the planet Mercury.
Mariner 10 and Messenger.
none
john William has explored the planet mercury... but no one has been sent out to this planet
From what I have learned, there has not yet been a robot that explored Mercury from closeup. They see Mercury since it is able to be seen by the naked eye in certain times of the night and day. It can also be seen with a telescope. So in all: There has not yet been a robot to explore Mercury from what I know. I apologize if this is incorrect.
NASA's MESSENGER spacecraft and the European Space Agency's BepiColombo mission are the main spacecraft that have explored Mercury. MESSENGER orbited Mercury from 2011 to 2015, providing detailed data and images of the planet. BepiColombo, a joint mission between ESA and JAXA, was launched in 2018 and is in the process of studying Mercury's surface and magnetic field.
Yes it has, by remote space vehicles, but not by humans directly.
mercury venus mars Jupiter Saturn uranus and neptune
in terms of satalites and rovers, mars, venus, jupiter, saturn, mercury
Mercury has only been explored by space probes, specifically Mariner 10 in 1973, and MESSENGER in 2004. Unrelated to the planet are the Mercury spy satellite program of the 1990s, and the 1959-1963 human spaceflight program Project Mercury.