Complex sentence: The 1970s in science and technology reached its height with the ambitious Voyager Program, which sent the Voyager I and Voyager II unmanned expeditions to several of the outer planets in the solar system.
Split into simpler sentences: The 1970s in science and technology reached its hieght with the ambitious Voyager Program. The program consisted of the Voyager I and Voyager II unmanned expeditions sent to several of the outer planets in the solar system.