Pale Blue Dot: A Vision of the Human Future in Space

The next four chapters cover the Voyager missions in detail. The sixth chapter begins with a discussion of NASA’s nonscientific value: to generate visions of the future that motivate and inspire. Sagan acknowledges that as he writes Pale Blue Dot, the purpose of NASA is in question due to recent expensive failures (including the deadly Challenger mission). But Sagan argues that there have been many triumphs too. He lists scientific breakthroughs and the growth of a satellite communications network. He also notes that many of the successes have been due to missions without men or women at risk. He raises the question of whether human spaceflight is worth pursuing but, for now, argues that robot spacecraft have been worth the cost.

Sagan then describes the history of the Voyager program: its inception in the 1960s, funding in 1972, and final mission parameters after reaching Saturn. He describes the probes: as big as a house, with a plutonium power source and various instruments attached. Due to limited propulsion technology, the probes used gravity assists to reach as far as they have. One or both Voyager spacecraft explored Jupiter, Saturn, Uranus, Neptune, and their moons. They reached Jupiter in 1979 and Saturn in 1980 and 1981.