system
Given the following post, respond as if you're commenting on Reddit:
human
What has been/will be the eventual fate of all our space probes?

This includes probes both in space or on planets/moons themselves.
gpt
Either they will collide with a celestial object or they will evaporate.

Probes in orbits around other planets are, wherever possible, deliberately crashed at end of life. We just did this to the MESSENGER probe at Mercury.

This has the dual benefit of only contaminating the planets we want contaminated, and gives us some extra science - we can learn from the composition of the stuff it kicks up at impact.

Interstellar probes (Pioneers and Voyagers) will either enter another system and collide with something, or over a period of trillions of years, will evaporate.

There are lots of high-energy (ultraviolet and higher) photons in space. Occasionally one of these will knock an entire atom off a spacecraft. In the very, very long timescale this will evaporate the spacecraft.