Technically a satellite is something in orbit around a planet, so there cannot be any satellites ON Mercury.
I will assume you mean satillites in orbit around Mercury.
Mariner 10 was the first probe sent to Mercury, however it orbited the sun (i.e. was not technically a satellite of Mercury) however it's prime purpose was to observe Mercury.
The probe MESSENGER and the two probes from the BepiColombo mission are currently the only satellites orbiting Mercury.
There are no known satellites of Mercury.
Mercury has no satellites.
Mercury has no natural satellites.
The planet Mercury has no natural satellites.
No natural satellites of Mercury have been discovered.
Mercury has no natural nor artificial satellites.
Mercury has no satellites.
Mercury has no natural satellites. The only man-made satellite, which crash-landed onto the planet was Messenger.
No natural satellites of the planets Mercury or Venus have ever been discovered.
Mercury and Venus do not have any natural satellites (Moons).
Mercury does not have any known natural satellites or moons. It is one of the few planets in our solar system that does not have a moon orbiting around it.
mercury does not have any satellite.