Such a mission would allow all the planets, even distant Pluto, to be reached in less than a decade, rather than the multiple decades such a journey would otherwise take. But this trick cannot be attempted at any random time, even in any random year or century. The planets, each one on its own orbit around the Sun, need to be arranged in just the right way, like beads strung on an arc, stretching from Earth to Pluto. Like a secret passageway appearing only briefly every couple of centuries, the motions of the planets line up to create such a conduit only once every 175 years.
