Into the great unknown: Juno, the probe to peel back Jupiter's curtain
From Fukushima to the darkest corners of the ocean, robots built for extreme environments and an appetite for discovery continue to enlighten our understanding of places too dangerous to tread. Those launched into deep space may be the most daring examples, continually pushing the limits of human ingenuity and expanding our understanding of the universe. In this series New Atlas will be profiling space probes, both past and present, tasked with pushing the boundaries of science by leading us into the great unknown. This week: a spacecraft built to unravel the mysteries hiding behind Jupiter's colorful clouds.
Launched: August 2011
Subject of study: Jupiter
Current location: In a 53-day orbit around Jupiter
As the oldest and most giant of our gas giants, Jupiter is suspected of hiding some key secrets of the early solar system beneath its thick, swirling and downright stunning sheath of cloud cover. Galileo made the first observations of the planet more than 400 years ago and a number spacecraft have paid it a visit since. But NASA’s Juno mission was to be a little different, sending along a spacecraft to peer beneath the cloud cover and study the planet’s insides for the first time.
Named after the mythological Roman goddess who saw through the cloudy veil her partner Jupiter formed to conceal his true identity, Juno set sail for Jupiter in August of 2011. Lifting off from Cape Canaveral atop an Atlas V rocket, Juno was to spend five years traveling to its destination, including a flyby of Earth, before it performed a final course correction and 35-minute engine burn to slip into orbit around Jupiter in 2016.
In doing so, Juno became the first spacecraft to enter orbit around Jupiter since Galileo in 1995, and the first to ever orbit its poles. The Voyager probes, Pioneer 10, Cassini and New Horizons are just some of the other spacecraft to pay Jupiter a visit by zipping past at different points over the last decade, but none were equipped to intensely study how it formed and how it continues to evolve.
Fitted out with gravity instruments, magnetometers, particle detectors, an ultraviolet imaging spectograph, infrared mapping devices, a microwave radiometer and, of course, a camera, Juno was built to bring us new insights on Jupiter’s gravitational and magnetic fields, its atmosphere and its composition.
By better understanding Jupiter, we may come to better understand the solar system and our place within it. Scientists see the gas giant as an early piece of the puzzle, forming at the same time as the Sun and sharing some similarities in terms of chemical makeup, consisting almost entirely of hydrogen and helium.
By virtue of its size and its status as the first gas giant to take shape, Jupiter is thought to have had a major impact on its surroundings. For example, scientists credit Jupiter’s presence for the fact that there is an asteroid belt between it and Mars rather than another planet, and believe it has repelled many Earth-bound comets back out toward the edges of the solar system.
The sheer mass of Jupiter is also believed to have shaped the orbits of other planets in our solar system, while its core could hold key clues to how heavy elements, which gave rise to rocky planets like Earth and Mars, made their way around the solar system.
And already Juno is starting to offer some profound lessons from its elliptical orbit, which sees it circle Jupiter from north to south every 53 days.
It has revealed the planet’s famous colorful bands extend thousands of kilometers below the surface where they clash with a complex magnetic field. It used its microwave radiometer to probe the roots of the Great Red Spot, finding the famous centuries-old storm penetrates around 320 km (200 mi) below the surface. It also measured Jupiter’s magnetic field and found it to be much stronger than expected, around 10 times stronger than any found on Earth, and found its atmosphere to be asymmetrical, with vast differences between the huge cyclones at the north and south poles.
Hard science aside, the images that Juno has managed to capture of Jupiter and its cloudy exterior are simply stunning.
Initially, Juno was actually designated a tighter 14-day orbit, but malfunctioning valves prevented an engine burn that was to enable this final, crucial course correction. So a 53-day orbit at a greater distance from Jupiter’s swirling cloud tops is what mission control were left to work with, which means it spends less time gathering observations and more time drifting through space.
NASA compensated for this in mid-2018 by approving a 41-month mission extension, funded through to 2021. All of Juno’s instruments are in good condition and capable of achieving the mission’s science objectives, it’s just that they need more time to do it. The spacecraft will meet its demise in July 2021, when it will be commanded to deorbit and burn up in the Jovian atmosphere.
In next week's edition of "Into the great unknown" we look at New Horizons, a mission to study Pluto, and beyond. For more on pioneering space probes, check out previous installments.
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