Io

Io is a moon of Jupiter discussed in Arthur C. Clarke’s 2010: Odyssey Two and its 1984 film adaption.

2010: Odyssey Two
David Bowman left the Discovery spacecraft parked at the inner Lagrange point, on the line between Jupiter and Io in 2001. Io is described as having volcanoes, and tremendous electrical discharges - with Jupiter's magnetic field spinning round every ten hours. The Discovery spacecraft was drifting more and more rapidly toward Io - though sometimes it accelerates, and sometimes even moves backward. This behaviour sets the time of impact, within two or three years. The NCA determined all too late, that gravitation wasn’t the only force acting on the Discovery spacecraft.