First telescopes and in recent decades eight deep space probes were used to examine the largest planet in the solar system.

NASA is returning to the gas giant with a large spacecraft called Juno. Equipped with unique sensors,

Juno will look deeper into the planet's structure than ever before to find out the

answers to basic questions about Jupiter's make up and how it formed.

Scott Bolton Principal Investigator, Juno: Juno's looking for how Jupiter

formed and really how planets are made in general.

We're very much looking for the recipe for planets.

The special thing about Juno is we're really looking at one of the first steps,

the earliest time in our solar system's history.

Right after the sun formed, what happened that allowed the planets to form

and why are the planets a slightly different composition than the sun?

NARRATOR: Jupiter is so far away from Earth that even when it is at its closest to us,

it will still take a radio signal moving at the speed of light about 34 minutes to cross the distance.

Getting Juno on a course to reach the distant planet is the job of an Atlas V rocket,

one of the largest in NASA's catalog.

Already been used to loft several NASA missions for the Launch Services Program,

including the New Horizons spacecraft on its way to Pluto.

Omar Baez Launch Director, Juno: It's flown as I said, 28 times, pretty challenging missions,

pretty challenging payloads.

It's got a heritage that goes back to the Atlas I in some of the components and in the upper stage,

so it's an evolution of a family in its current configuration and shape and form.

I'd say it's pretty robust.

NARRATOR: The alignment of Earth and Jupiter leaves the mission's managers with a limited window to launch the spacecraft.

John Calvert Mission Manager, Juno: Juno only has a 22-day launch window,

or else we're down for another 13 months until our next opportunity.

And so it's those kinds of challenges with making sure you do all the

little things necessary to maximize the opportunities you get for those 22 days.

NARRATOR: Even riding a powerful rocket into space will not be enough on its own to push Juno to its target.

The spacecraft still needs the kind of assist only a planet can provide.

That's why Juno will go into an orbit that will bring it past Earth two years

after launch and use the Earth's gravity to slingshot it out to Jupiter, arriving there in August 2016.

Aside from distance, Jupiter offers unique challenges to a spacecraft,

such as a radiation field rivaled in intensity only by the sun.

BOLTON: We have a box in the middle of the spacecraft that we call a vault and it's made out of

titanium and that shields all the electronics from the hazardous radiation.

We're very much an armored tank going to Jupiter.

NARRATOR: Just as Juno is building on the knowledge gained with past missions to Jupiter,

future missions will build on Juno's findings.

BOLTON: If we could start to understand the role that Jupiter played and how the planet formed and how

that eventually governed the creation of the other planets and the Earth and maybe even life itself,

then we know a little bit about how to look for other Earth-like planets,

maybe orbiting other stars and how common those might be and the roles

that those giant planets that we see orbiting the other stars play.

NARRATOR: NASA's Launch Services Program has dispatched several probes to deep space in recent years,

including the Opportunity and Spirit rovers on Mars, the Cassini spacecraft that is studying Saturn

and the New Horizons mission that is on its way to Pluto.

NARRATOR: The schedule does not lighten for the LSP team after Juno.

Along with an experimental weather satellite, missions to the moon and to Mars are set for launch this year.

CALVERT: Really, all these missions that LSP is involved in, that NASA's involved in, they're all

precursors to the bigger picture of getting humans out beyond Earth orbit, to Mars, to an asteroid.

NARATOR: For now, though, the team is focused on getting Juno safely on its way to Jupiter.

Omar Baez Launch Director, Juno: I will be celebrating when I hear that the spacecraft

has separated successfully and the solar arrays are out.