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Juno mission to Jupiter

Juno above Jupiter's poleJuno above Jupiter's poleOn the morning of 5th July 2016 the Juno space probe, which had been travelling through the Solar System since its launch in 2011, went into orbit around Jupiter. To do so, it had to slow down and be captured by the giant planet’s gravity. The braking manoeuvre, called an “orbit insertion burn”, relied on the probe's rocket engines firing at exactly the right moment and for the correct length of time. Juno then went into orbit round Jupiter, collecting data that help astronomers find out what lies beneath the planet's thick clouds. At times, Juno flies to within less than 5000 kilometres (3000 miles) of Jupiter’s cloud tops. It will remain in orbit until July 2021 (extended from July 2018).


The Juno probe was launched on 5th August 2011 and travelled nearly three billion kilometres to reach Jupiter. It is fitted with a three giant solar panels, which generate just a few hundred watts of electricity. But, according to Dr Scott Bolton, Juno’s principal investigator, from Southwest Research Institute in San Antonio, Texas, this should be easily enough to power Juno’s instruments over its predicted life span.

Juno space probe approaches Jupiter Juno space probe approaches Jupiter
Jupiter's internal layersJupiter's internal layersJuno is equipped with nine instruments, placed, along with its control systems, inside a thick-walled titanium box to protect them from Jupiter’s powerful magnetic field and radiation belts. These enable scientists to carry out a study of Jupiter's auroras (similar to the northern lights visible in polar regions on Earth) and to probe the planet's thick atmosphere. Microwave detectors determine how much water there is in the atmosphere, and so reveal how much oxygen was present in Jupiter’s region of the Solar System when it was formed. Meanwhile, Juno is also sending back stunning panoramic images of the planet via JunoCam and measuring the thickness of the Great Red Spot.

Image of Great Red Spot taken by JunoImage of Great Red Spot taken by Juno

An image of Jupiter taken by JunoAn image of Jupiter taken by JunoJuno is carrying out precise measurements of Jupiter’s gravity in order to find out whether it has a solid rocky core or whether the planet’s centre is made of gas at an incredibly high density. This is reckoned to be 80 million times the Earth’s atmospheric pressure, or, as one mission scientist put it: “Like a thousand elephants, one on top of the other, with the bottom elephant standing on a stiletto."


Swirling winds in Jupiter's atmosphereSwirling winds in Jupiter's atmosphereIn March 2018, Juno found that Jupiter’s striped bands, caused by immensely powerful winds, extend to a depth of about 3000 km (2000 miles) below the surface. These have a slight distorting effect on Jupiter’s gravitational field, and it was this that was picked up by Juno’s detectors. It appears that the gas currents—five times as strong as the most powerful hurricanes on Earth—are part of a convection system in Jupiter’s atmosphere.


A view of Jupiter's southern polar regionA view of Jupiter's southern polar region
Lego's figurines on board JunoLego's figurines on board JunoJuno is carrying passengers: three Lego models (made of aluminium rather than plastic bricks) depicting the Roman goddess Juno, her husband Jupiter and the Italian astronomer Galileo Galilei.

In July 2021, after completing 35 orbits of Jupiter, Juno’s mission is scheduled to come to an end. Its controllers will send it plunging into the Jupiter’s atmosphere, ensuring that the probe will not crash into one of Jupiter’s moons and possibly contaminate Europa, which scientists suspect could be host to living things.

Juno's flight path to Jupiter

Juno’s instruments picked up the radio waves generated by Jupiter's auroras, which the scientists converted to sounds. So it is now possible to hear Jupiter “talking”.

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