1. Juno’s Mission to Jupiter
The Juno Spacecraft will reach Jupiter, arriving in orbit about July 4, 2016.
The missions principal scientific goal is to understand the origin and evolution of Jupiter.
The instruments onboard Juno will see, for the first time, below the gas giants dense cloud cover.
(This is why the mission was named after the Roman goddess, who was Jupiter's wife, and who could also see through clouds.)
Original text:
The Juno Spacecraft will reach its destination of Jupiter, arriving in orbit about July 4, Juno’s mission’s principal scientific goal is to understand the origin and evolution of Jupiter.
With its suite of science instruments, The Juno spacecraft will, for the first time, see below Jupiter's dense cover of clouds. (This is why the mission was named after the Roman goddess, who was Jupiter's wife, and who could also see through clouds.)

2. The Juno spacecraft launched from Cape Canaveral, Fla. , on Aug
The Juno spacecraft launched from Cape Canaveral, Fla., on Aug. 5, 2011, and, has been traveling toward Jupiter for nearly 5 years.

3. Its trajectory has followed a route to Jupiter that included a gravity-assist “slingshot” using a flyby of Earth in 2013.
Once at Jupiter the spacecraft will go into a polar orbit, skimming to within 3,100 miles (5,000 kilometers) above the planet's cloud tops, for over a year.

4. Under its dense layer of clouds, Jupiter holds the secrets to the processes that formed our solar system. The gas giant can also help us understand the planetary systems being discovered around other stars.
Jupiter radiates more energy than it receives from the sun which adds to the riddles of its make-up and processes.
The spacecraft will investigate the possibility of a solid planetary core, map Jupiter’s magnetic field, measure the amount of water and ammonia in the atmosphere, and observe the planet’s auroras.
Original text:
Underneath its dense cloud cover and with its Great Red Spot, Jupiter safeguards secrets to the fundamental processes and conditions that governed our solar system during its formation. As our primary example of a giant planet, Jupiter can also provide critical knowledge for understanding the planetary systems being discovered around other stars.
Jupiter also radiates more energy than it receives from the sun which adds to the riddles of its make-up and processes.
Juno provides the first survey and exploration of the three-dimensional structure of Jupiter's polar magnetosphere. Juno will investigate the existence of a solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet's auroras.

5. Jupiter’s atmosphere, which makes up most of the planet, is composed almost entirely of molecular hydrogen.
Approximately 10% is composed of helium with a small fraction made up of ammonia, sulfur, methane, and water vapor.
Traveling from the outermost edges of Jupiter toward its center, pressure and temperature goes up.
These increases cause the gases to separate into layers. 
Deep down, the hydrogen changes from a gas to a liquid. It can even become metallic.
Observed for over 200 years, the great Red Spot is thought to be a hurricane caused by the interaction of the atmosphere’s layers.
Original text:
Jupiter’s atmosphere is very complex, with layers of molecular hydrogen and turbulent winds over 400 mph and extremely high temperatures (shown in Kelvin on this picture). Observed for over 200 years, the great Red Spot is thought to be a hurricane caused by the interaction of the atmosphere’s layers.
Below the atmosphere, the planet is thought to have a layer of liquid metallic hydrogen and a rocky, maybe an icy core formed under the extremely high atmospheric pressures.
Source:
Jupiter’s Atmosphere

6. While there have been several flyby missions, the Galileo mission in 1995 has been the only other spacecraft to orbit Jupiter.
One of its jobs was to drop a probe into Jupiter's atmosphere. As it fell, the probe returned data on temperature, pressure, composition, wind speeds, and prevalence of clouds.
The probe returned data for 61 minutes falling to 200 km (124 miles) below the cloud tops.
It finally failed because it got too hot (this was expected!); the temperature when it ceased to function was 1520C (about 3000 F)

7. From its observations Juno will follow-up on Galileo and its probe to provide important additional insights in these unanswered questions:
What is the structure inside Jupiter?
How did Jupiter form?
How much water or oxygen is in Jupiter?
Does Jupiter rotate as a solid body, or is the rotating interior made up of concentric cylinders?
Is there a solid core, and if so, how large is it?
How is its vast magnetic field generated?
How are atmospheric features related to the movement of the deep interior?
What are the physical processes that power the auroras?
What do the poles look like? Juno uses a spinning, solar-powered spacecraft in a highly elliptical polar orbit that avoids most of Jupiter's high-radiation regions. The designs of the individual instruments are straightforward and the mission did not require the development of any new technologies.

8. The spacecraft's main body measures 11. 5 feet (3
The spacecraft's main body measures 11.5 feet (3.5 meters) tall and 11.5 feet (3.5 meters) in diameter.
The mission's science objectives will be achieved with a payload of nine instruments.
Among these instruments are ultraviolet and infrared spectrometers, plasma and particle detectors, and a radiometer.
The spacecraft will also carry a color camera, called JunoCam, to provide the public with the first detailed glimpse of Jupiter's poles.
Juno was built by Lockheed Martin Space Systems in Denver, Colorado for the NASA’s Jet Propulsion Laboratory.

9. Juno carries a plaque dedicated to the famous astronomer Galileo Galilei provided by the Italian Space Agency.
Among his many achievements, Galileo discovered that moons orbited Jupiter in These satellites -- Io, Europa, Ganymede and Callisto -- are also known as the Galilean moons.
It also includes - in Galileo's own hand - a passage he made in 1610 of observations of Jupiter:
"On the 11th it was in this formation - and the star closest to Jupiter was half the size than the other and very close to the other so that during the previous nights all of the three observed stars looked of the same dimension and among them equally afar; so that it is evident that around Jupiter there are three moving stars invisible till this time to everyone."

10. The spacecraft also carries three Lego figurines representing Galileo, the Roman god Jupiter and his wife Juno. Although most Lego toys are made of plastic, Lego made these figures of aluminum to endure the extreme conditions of space flight.
To show his status as a thunder god, Lego gave its Jupiter mini-figure a lightning bolt to hold, while Juno has a magnifying glass to signify her search through the truth. Galileo holds a tiny sphere resembling Jupiter (the planet) and, of course, a telescope.
Lego took special care to ensure they wouldn’t interfere with the operation of Juno in any way.

11. Voyagers 1 and 2 - 1979 Pioneer 10 - 1973 New Horizons - 2007
As noted earlier, NASA's Galileo made the first voyage to orbit Jupiter, arriving in
Initial flights to Jupiter were flybys for both science and used the giant planet’s gravity to propel spacecraft onto trajectories deeper into the solar system:
Pioneer December 1973
Pioneer December 1974
Voyager 1 -- March 1979
Voyager 2 -- July 1979
Ulysses -- February 1992.
New Horizons -- February 2007
Galileo

12. After arriving in Jupiter its elliptical orbit in early July 2016, the spacecraft is planned to orbit the planet for 20 months (37 orbits). At the end of this mission in February 2018, Juno will deorbit into Jupiter’s dense atmosphere the craft has been studying and provide data during its final plunge.
Stay tuned for answers from Juno at Jupiter.