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
Gaea (crater) Gaea (crater) Gaea is an impact crater on Amalthea, one of the small moons of Jupiter. The crater is 75 km wide and at least 10–20 km deep. Its center coordinates are 50°S, 95°W. Gaea is one of two named craters on Amalthea, the other being Pan. It is named after the Greek goddess Gaia. Third of Gaea's interior is covered by a bright spot – the largest on Amalthea. Its brightness is at least 2.3 times greater than outside. This spot is about 25 km wide and appear to be extended outside the crater. Gaea is located near the