Galileo probe burning up in Jupiter's upper atmosphere, artwork. The Galileo probe was launched in 1989 to study Jupiter and its moons. It arrived at Jupiter, the solar system's largest planet, in 1995. It then released an atmospheric probe into the atmosphere, which showed that the atmosphere was largely hydrogen and helium. After this it made detailed studies of some of Jupiter's moons. It far exceeded its planned operational lifespan of around two years, surviving the intense Jovian radiation belts and the vacuum of space. It sent back a huge amount of scientific data about the Jovian system, but was crashed into Jupiter on 21st September 2003.