British engine brakes Juno probe to place it into Jupiter orbit

The spacecraft can now begin a series of observations of the conditions below the planet’s swirling cloud systems and into the interior structure of the Solar System’s largest planet. One of the most crucial components of the orbital insertion manoeuvre, a British-made rocket engine, worked perfectly despite the ferocious radiation levels close to Jupiter.

Jupiter, with its many moons orbiting the giant planet composed mainly of hydrogen, has for centuries been considered as model for the entire Solar System; it was Galileo Galilei’s extrapolation of his observations of the orbits of the four largest moons in the 15^th century that led to him supporting the heliocentric model of the System, founding the modern science of observational astronomy and in turn, landing him in so much trouble with the Catholic Church.

The Juno mission is an expansion of this, designed in part to test theories about the early history of the Solar System: it is believed by some that Jupiter originally formed much closer to, or further away from the Sun, and gradually moved to its current orbit. Juno carries eight instruments that will look down onto the planet from its orbit, which is designed to avoid the highest radiation regions Jupiter, and measure its gravity, the abundance of oxygen and hence water in its composition, its magnetic fields (the largest of any of our planetary neighbours), and determine the composition of its atmosphere and lower layers. It will also take the closest images of Jupiter yet obtained when it moves into an even smaller orbit in October, a few thousand kilometres above the top of its atmosphere. The water levels are key to determining where the planet - believed to be the oldest in the solar system – formed.