The Planet of Doubt Jupiter and Saturn and on the surface of Uranus itself. At the time "The Planet of Doubt" takes place at the turn of the 22nd century, the limited range of the spaceships ensures that Uranus can only be reached from the American base on Titan when Saturn reaches conjunction with Uranus, an event that occurs once every forty years. The Young expedition explored the planet's south pole in 2060; now Hammond takes his ship, the "Gaea", to the north pole. Finding an ocean at the north pole, Hammond sends the "Gaea" spiraling southeast until they reach land. They find the
Exploration of Uranus In 2011, the United States National Research Council recommended a Uranus orbiter and probe as the third priority for a NASA Flagship mission by the NASA Planetary Science Decadal Survey. However, this mission is considered to be lower-priority than future missions to Mars and the Jovian System.<ref name="2013-2022/Decadal"></ref> A mission to Uranus is one of several proposed uses under consideration for the unmanned variant of NASA’s heavy-lift Space Launch System (SLS) currently in development. The SLS would reportedly be capable of launching up to 1.7 metric tons to Uranus. In 2013, it was proposed to use an electric sail (E-Sail)