On July 4, Juno will become only the second spacecraft to reach orbit around Jupiter. The Jupiter Near-polar Orbiter (Juno) is a NASA New Frontiers mission currently en route to the planet Jupiter. It's projected to cost $1.1 billion over its life.

Juno will improve our understanding of the solar system's beginnings by figuring out the origin and evolution of Jupiter. It will be the second spacecraft to orbit Jupiter, following the Galileo probe which orbited from 1995-2003.

Juno will orbit Jupiter in a "polar" orbit, going around the planet in a north-south orientation that will carry it repeatedly over Jupiter's geographic and magnetic polar regions.

Juno spacecraft will closely investigate Jupiter's atmosphere. The spacecraft will also probe Jupiter's magnetic and gravitational fields.

According to lead investigator for the Juno mission, Scott Bolton of the Southwest Research Institute, the probe is now scheduled to arrive and Juno is speeding by at four miles persecond.

Scientists expect Juno to increase its speed as it gets closer to the colossal planet, due to its powerful gravitational forces. Upon rendezvous, the probe will reach speeds of 40 miles per second just before it blasts off its rocket engines to be placed into orbit.

"Throughout the project, including operations, our review process has looked for the likely, the unlikely and then the very unlikely," Juno project manager Rick Nybakken said.

"Now we are looking at extremely unlikely events that orbit insertion could throw at us."