Zach has just been admitted to the Solar System Exploration for Gifted Youngsters course! He'll be the first Earthling admitted to this prestigious class. Since his dad is an astronaut, Zack has known for a while that aliens exist... but going to school with a Neptunian teacher and students who come from Saturn, Mars, or Jupiter is a whole different experience! Today, the flying school is heading to Ganymede, a moon of Jupiter that's been turned into a junkyard.