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article imageJuno to get 'up-close and personal' with Jupiter on July 4th

By Karen Graham     Jun 29, 2016 in Science
After traveling nearly 1.8 billion miles (2.8 billion kilometers), NASA's Juno probe is only five days away from an historic encounter with Jupiter, the largest planet in our solar system, and the planet the greatest distance away from our sun.
But to get up-close and personal with the Jovian giant, on July 4, Juno will perform a suspenseful and daring insertion maneuver, meant to put the probe into orbit around Jupiter.
The 35-minute engine-burn maneuver is meant to slow the probe down and is critical to the success of the mission. says that if this maneuver doesn't go exactly as planned, Juno will fly right past Jupiter, putting an end to the $1.1 billion mission.
"It's a one-shot deal. I mean, the whole thing's riding on this JOI — Jupiter orbit insertion — activity on July 4," Scott Bolton, Juno's principle investigator at the Southwest Research Institute in Boulder, Colorado, said in a news conference on June 16. "Somebody asked, 'When does the nail-biting start?' It's already started."
It will take Juno 14-days to complete one orbit around the massive planet, according to Global News, and because Jupiter spins every 10 hours, once Juno is firmly in orbit around Jupiter, it will circle the planet 37 times during 20 months, skimming to within 3,100 miles (5,000 kilometers) above the cloud tops. This will be the first time a spacecraft will orbit the poles of Jupiter, and scientists are looking forward to finding out about Jupiter's mysteries.
Launch of Juno on an Atlas V from Cape Canaveral on May 8  2011.
Launch of Juno on an Atlas V from Cape Canaveral on May 8, 2011.
What do we know about Jupiter?
Perhaps it is best to start with what we do know about Jupiter. The planet is the largest in our solar system and is the greatest distance from the sun. To put this in perspective, Jupiter is five times further from the sun than Earth, (That's 484 million miles (778 million km) or 5.2 Astronomical Units), and it receives 25 times less sunlight than the Earth.
Dark spots mark impact sites of comet fragments on Jupiter.
Dark spots mark impact sites of comet fragments on Jupiter.
Jupiter has an enormous magnetic field and because of this it actually could be said to be a solar system all by itself. At last count, there were about 67 moons circling the planet, 50 of them named and 17 more as yet unconfirmed. The giant planet has three outer rings, called the gossamer rings. As for what type of planet Jupiter is categorized as being — it is a gas giant.
Gas giants are planets composed mainly of hydrogen and helium. Did you know our solar system has four gas giants? Besides Jupiter, there is also Saturn, Uranus, and Neptune. How cool is that? All four of these gas giants are called Jovian planets, after Jupiter. We do know that Jupiter's core is made up of dense rocks and ice.
Primary objectives of the Juno Mission
Juno's scientific instruments are tucked away inside a 400-pound (180 kilograms) titanium vault that will protect them from the radiation surrounding Jupiter. As the probe skims along between the radiation belt and the planet, it will be taking precise measurements of the ratio of oxygen to hydrogen, measuring the amount of water on the giant planet.
Measurements of its magnetic field and gravity will help in determining the precise mass of Jupiter, as well as its composition. Additional measurements will assess the temperature, atmosphere, thickness of the clouds and a number of other parameters for scientists. This will give us Earthbound folks a better understanding of the planet's history.
Solar arrays power Juno
This writer read that the Juno probe needs only about the same amount of power as a blender, according to NASA. That statement got this writer's attention. How could this be? It all has to do with three impressively large solar arrays that extend from Juno's body.
In order to generate enough power operating such a great distance from the sun, NASA engineers designed solar arrays with vast surface areas. Each of Juno's three solar arms is about 29 feet (8.8 meters) wide. On Earth, the three together would be able to generate 14 kilowatts of power. On reaching Jupiter, the arrays will generate 500 watts of power.
In a clean-room environment at Astrotech s payload processing facility in Titusville  Fla. technicia...
In a clean-room environment at Astrotech's payload processing facility in Titusville, Fla. technicians conduct an illumination test on the solar array panels for NASA's Juno spacecraft.
NASA/Jack Pfaller
When the arrays are fully extended, Juno is close to 65 feet (20 meters) across. But in order to fit all that into the nosecone of the launch rocket, the arrays were broken down into four pieces and connected with hinges. Until the probe was deployed, it was getting no solar power. Once it deployed and the three arrays were extended, it has remained so and will continue to draw what little solar energy there is so far from the sun.
Just a bit of trivia about the Juno mission
The Galileo plaque aboard Juno  provided by the Italian Space Agency.
The Galileo plaque aboard Juno, provided by the Italian Space Agency.
The Italian Space Agency provided a plaque that Juno is carrying, dedicated to Galileo Galilei. The aluminum plaque depicts a portrait of Galileo and a text in Galileo's own hand, penned in January 1610, while observing what would later be known to be the Galilean moons. The translation: "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."
Three LEGO figurines representing the Roman god Jupiter  his wife Juno and Galileo Galilei are shown...
Three LEGO figurines representing the Roman god Jupiter, his wife Juno and Galileo Galilei are shown here aboard the Juno spacecraft.
Juno is also carrying three Lego figurines depicting Galileo, the Roman god Jupiter and his wife Juno. While Lego toys are normally made of plastic, these special figurines are made of aluminum to endure the rigors of space flight. Juno holds a magnifying glass as a sign of searching for the truth and her husband holds a lightning bolt. The third Lego crew member, Galileo Galilei, has his telescope with him on the journey.
NASA TV Events Schedule
Monday, July 4 -- Orbit Insertion Day
9 a.m. PDT (Noon EDT) -- Pre-orbit insertion briefing at JPL
7:30 p.m. PDT (10:30 p.m. EDT) -- Orbit insertion and NASA TV commentary begin
10 p.m. PDT (1 a.m. EDT on July 5) -- Post-orbit insertion briefing at JPL
To watch all of these events online, visit:
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