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Juno: Unlocking Jupiter's Mysteries (with videos)

by Dani Johnson

July 18, 2013

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Image Credit: NASA

Juno is a NASA New Frontiers mission to Jupiter that launched on August 5th, 2011 and is due to arrive in orbit in July 2016. This mission is unique because it is the first that will be placed in a polar orbit around its target in order to study Jupiter's polar magnetosphere, especially the auroras. Juno's principal goal is to understand how Jupiter formed. By understanding Jupiter's formation we will better understand the formation of the entire Solar System. This will also help us understand how other star systems with planets formed. Instead of having an acronym for a name, this mission is named for the mythological Jupiter's wife, Juno. According to the myth, Jupiter wanted to do some things behind his wife's back, so he covered himself and his mischeif up with a cloud. Juno used her powers to see through the clouds to find the true nature of her husband's actions. Likewise, the spacecraft will use its "powers" (instruments) to peer through the clouds surrounding Jupiter, the planet, and find the true nature of the winds underneath.

Mission Timeline
  • Launch - August 5, 2011

  • Deep Space Maneuvers - August/September 2012

  • Earth flyby gravity assist - October 2013

  • Jupiter arrival - July 2016

  • Spacecraft will orbit Jupiter for about one year (33 orbits)

  • End of mission (deorbit into Jupiter) - October 2017

If I understand the basics of Juno's trajectory correctly, Juno is being launched off of Earth and flung into orbit around the Sun. Juno makes a complete orbit before it meets back up with Earth and uses the planet's gravity to fling it faster towards Jupiter at just the right angle so it can be captured into an unusual orbit. It all sounds complicated, but this video will draw it out visually:

The polar orbit that Juno will fall into around Jupiter is one that isn't usually fallen into naturally, but it offers some advantages for mapping. The spacecraft will pass over every part of the planet, but that also means that it can't view any one spot for a very long time. Here are a few video animations of the orbit:

This video demonstrates the way the craft will be able to "see" every portion of the planet:

In this video, you get to see what the polar orbit would look like from a farther vantage point:

Juno looks like a shiny, metal propeller that must have dislodged from some strange craft and got lost in space. There are three "blades" that are attached around a hexagonal body. The engineers involved strategically placed eight instruments on the sides of the spacecraft. According to the Mission Page by SWRI, "Juno was carefully designed to meet the tough challenges in flying a mission to Jupiter: weak sunlight, extreme temperatures and deadly radiation. The spacecraft is covered in thermal blankets to protect it from the extreme environment of space. All of the most-sensitive electronics are placed inside an armored vault to shield them from Jupiter's deadly radiation." Juno's instruments include:
  • A gravity/radio science system (Gravity Science)
  • A six-wavelength microwave radiometer for atmospheric sounding and composition (MWR)
  • A vector magnetometer (MAG)
  • Plasma and energetic particle detectors (JADE and JEDI)
  • A radio/plasma wave experiment (Waves)
  • An ultraviolet imager/spectrometer (UVS)
  • An infrared imager/spectrometer (JIRAM)
  • A color camera called JunoCam

Juno will spin for it's entire journey, which makes it really stable and easy to control. According to NASA, "at three rotations per minute, the instruments' fields of view sweep across Jupiter about 400 times in the two hours it takes to fly from pole to pole".

This will be the first time we've sent a solar powered craft this far from the Sun. The solar panels are pretty big to compensate for the great distance, and Juno will always have to position its solar-side to the sun to maintain power.

Above Image: Juno spacecraft and its science instruments.

Image credit: NASA/JPL

Theres no doubt that we are going to learn things about Jupiter that the Juno team hadn't anticipated, but specifically Juno will:
  • Determine how much water is in Jupiter's atmosphere, which helps determine which planet formation theory is correct (or if new theories are needed)

  • Look deep into Jupiter's atmosphere to measure composition, temperature, cloud motions and other properties

  • Map Jupiter's magnetic and gravity fields, revealing the planet's deep structure

  • Explore and study Jupiter's magnetosphere near the planet's poles, especially the auroras — Jupiter's northern and southern lights — providing new insights about how the planet's enormous magnetic force field affects its atmosphere

The JunoCam was placed on the spacecraft specifically for the public to be able to interact with the mission. The idea is that amateaur astronomers can assist the scientists real-time in this mission. Some duties include predicting what cloud features will be visible when the craft orbits close enough to take a picture. Since the camera wasn't actually needed for the Juno mission, it's data reserve is quite low and the unusual polar orbit is not optimized for imaging. There's only about 40 megabytes of space available for the images, which amounts to about 10-100 photos depending on how large each image is. We also have no idea how Jupiter's intense radiation is going to effect the physical camera or how it might interfere with the images taken. Emily Lakdawalla actually wrote an incredible blog post that covers the JunoCam in greater detail.

As stated on NASA's mission website, "The Juno mission is the second spacecraft designed under NASA's New Frontiers Program. The first was the Pluto New Horizons mission, launched in January 2006 and scheduled to reach Pluto's moon Charon in 2015. The program provides opportunities to carry out several medium-class missions identified as top priority objectives in the Decadal Solar System Exploration Survey, conducted by the Space Studies Board of the National Research Council in Washington."


by Dani Johnson

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