NASA's Juno Mission to Jupiter: Investigating a Colossus

Published by Tony Darnell on 29th Jun, 2016

Jupiter, the third brightest object in the night sky. This distant point of light has beckoned humanity for millennia in our quest for knowledge and our place in the universe.

Our fascination with the largest planet in the solar system has continued from antiquity and into the renaissance when, for the first time, humans looked up through a telescope. In 1610, using a telescope only one and a half inches in diameter, Galileo Galilei observed through this tiny telescope wonders that would fundamentally change our views of the universe forever.

Visible in this small telescope, and magnified about 20 times, tiny worlds were seen circling around this giant planet. What became known as the Galilean satellites, Io, Europa, Ganymede, Callisto, their existence provided a powerful argument that Earth may not be the center of the Universe, instead, the Earth may actually circle the Sun.

Much, much later, when humans started venturing into space, we sent missions to study the solar system’s colossus. First there was the arrival of Pioneer 10 in 1973, followed a year later by Pioneer 11; Voyagers I and II visited the planet in 1979; Ulysses studied Jupiter’s magnetosphere in 1992 and again in 2000; the Galileo spacecraft studied the planet in intricate detail in from 1995 until 2003, and it even launched a probe into the atmosphere of Jupiter itself; The Cassini probe approached the planet in 2000 and took very detailed images of its atmosphere; and, most recently, Jupiter was used for the New Horizons mission to accelerate the probe to Pluto in 2007.

Since that flyby of New Horizon almost a decade ago, we’ve had no orbiters or probes studying the largest planet in our solar system, until now.

Finally, a new mission is on its final approach to Jupiter.

Built by Lockheed Martin, Juno launched on August 5th 2011 atop an Atlas Five rocket and will enter into Jupiter’s orbit on July 4th 2016. This mission to Jupiter is a collaboration of many agencies: flight operations will be controlled from the Flight Control Center in Pasadena California at NASA JPL; The Goddard Space Flight Center handles the instrumentation

The Universities of Hawaii, California Institute of Technology, the University of Colorado at Boulder, and the Planetary Science Institute all make up the primary science investigators.

Juno is very large, it is 11 feet tall and 11 feet wide its three large solar panels have a total surface area of 650 square feet. It is this large for a reason, this is the first time a spacecraft has been sent beyond the asteroid belt using solar cells as its primary power supply - made possible by advances in solar cell efficiency.

After its launch and two years hurtling through the solar system Juno returned for a swing by Earth for a gravity assist. By firing its maneuvering thrusters at its greatest distance from Earth, this gave the spacecraft an added push as it flew past, using Earth’s gravity to exponentially increase its speed when it flew by, accelerating Juno to a speed of 87,000 miles per hour - the required velocity to reach Jupiter..

After five years, the spacecraft will finally arrive at its destination on July 4th 2016. As it enters into Jupiter’s gravitational influence it will begin to speed up to 160,000 mile per hour making Juno the fastest human made object in history. And now it must slow down or it will be lost in the depths of the solar system.

Its LEROS 1b main engine will ignite at the lowest point in Juno’s pass of Jupiter, slowing the spacecraft down and allowing it to be captured by Jupiter’s immense gravity. After two deceleration orbital maneuvers Juno will be in its eccentric 14 day polar orbit.

From this unique orbit, Juno will circle the planet 37 times over 20 months and will allow the on board instruments to study the atmosphere and interior of Jupiter. It also will protect Juno from the harmful radiation of the planet. Orbiting up high then ducking low to just 31,000 miles above the cloud tops means the spacecraft spends a short amount of time within the radiation belts of Jupiter. The main computer and other critical systems are further protected in a one centimeter thick titanium compartment within the main structure of Juno.

The design of the orbit and the spacecraft are meant to enable the 29 sensors and nine science instruments to study the planet Jupiter like never before. Juno will look inside the planet using magnetometers to Earth to measure the magnetic fields of Jupiter and its aurorae, infrared and Microwave sensors will look deep into the atmosphere to assess the abundance and distribution of water, and therefore oxygen, and provide insight into Jupiter's origins as well as the solar system’s formation.

By peering inside Jupiter’s core scientists hope to answer whether or not it has a condensed Hydrogen center which due to pressure and magnetism behaves like a metal.

By understanding the magnetosphere of the planet and taking measurements of the charged particles that Jupiter emits and absorbs in giant aurora, we will unlock not only the mystery of how the planet is structured but also how it sustains the energy to generate the storms that move throughout its atmosphere, including: where did the Great Red Spot come from?

The answer to this grand mystery of our solar neighborhood maybe just around the corner.

Using microwaves and spectroscopy, Juno will look for how much water and thus oxygen Jupiter has. Understanding the amount of water will also tell scientist the conditions in which the heavy elements collapsed to help form Jupiter and how the rest of its gaseous structure formed together due to the effects if gravity.

How and when Jupiter formed may hold clues to the process the rest of the solar system underwent during its formation. Including hints to where Earth’s water came from and why the inner planets are rocky.

When it’s mission is complete in February 2018, after two years and 37 orbits, Juno will be ordered to de-orbit and burn up in Jupiter’s outer atmosphere, this precaution will avoid any possibility of biological contamination of any of Jupiter’s moons, including Europa.

The probe will send back data of the environment of Jupiter until its final breakup.

Right now, Juno hurtles through space towards our largest planet, preparing for it’s arrival in just a few short months, its science instruments primed to unlock the mysteries of a world unimagined by Galileo when he first glimpsed its wonder through a telescope a little over 400 years ago.

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