While many people know about the Voyager missions launched in the 1970s and the New Horizons probe that visited Pluto in 2015, few are aware that the relationship between these two missions dates back to the 1960s. Had scientific goals been different at the time, Voyager might have taken the place of New Horizons, decades before the latter was ever conceived.
In 1964, Jet Propulsion Laboratory (JPL) scientist Gary Flandro noticed that a so-called “grand tour” of the outer solar system would be possible in the late 1970s given the impending alignment of Jupiter, Saturn, Uranus and Neptune. Such an alignment is exceptionally rare and occurs only once every 175 years. In keeping with tradition and recognizing the difficulties inherent in using unmanned probes, two missions were planned to increase the chances of success should one mission fail: Voyager 1 and 2. Of key importance, Pluto (at that time formally ...
