Final answer:
The answer is True. Unmanned space probes have visited all planets in our solar system, including flybys of Uranus and Neptune. These missions have significantly enhanced our knowledge of the solar system's varied and dynamic nature.
Step-by-step explanation:
To answer the question: All of the planets in our solar system have been visited by unmanned space probes such as Voyager, Viking, Mariner, among others, the correct response is True. Over the past decades, robotic explorers with names like Voyager, Pioneer, Curiosity, and Pathfinder have journeyed to every planet in our solar system. They have sent back a wealth of data and stunning visuals.
Although we have no orbiter missions for Uranus and Neptune at this time, flybys have been conducted for these planets as well. For instance, Voyager 2 flew by Neptune and Uranus, providing valuable data. It is intriguing to note that the outer solar system has proven considerably more geologically active and diverse than initially expected.