Just over 200 days of travel from the Sun, Pegasus reaches the largest planet of the solar system, Jupiter. Its danger lies in a menace lurking at its core - a churning mass of liquid metallic hydrogen that inflates a magnetic bubble around the planet, producing levels of radiation 500 times the dose that would kill a human.To repel these lethal rays, Pegasus generates its own magnetic field. Mission geologist Zoe is to land on Io, one of Jupiter's moons. As the most volcanically active world in the solar system, it's a geologist's heaven.