This gas giant contains most of the mass in the Solar System aside from that of the Sun itself. Most of this is hydrogen and helium, including tri-helium which is valuable for fusion reactors. A small percentage, but a giant absolute quantity, consists of heavy metals in the lithosphere. This lithosphere is small compared to Jupiter's diameter, but is probably bigger than the whole Earth. Unfortunately, the lithosphere is deep beneath the Jovian atmospheric surface, and exists under conditions of heat and pressure so great that no materials we can currently create would survive for more than instants on its surface. Perhaps several centuries from now we will be able to build machines capable of operating under such extreme conditions. In the meantime, suffice it to say that any culture which could solve the many problems of living on or in Jupiter would have more matter to exploit than the whole rest of the Solar System (again not counting the Sun itself) put together.
Answered by: http://alfonsoycia.blogspot.com