4 July 2016: the Juno spacecraft reached the orbit of Jupiter and brought a lot of Italy with it
Who better than a goddess like Juno could have given its name to this space mission to study the largest planet of the Solar System?
In Roman mythology, the god Jupiter was transformed into a cloud to hide his actions, but from Mount Olympus, the goddess Juno was able to peer through the clouds and discover the true nature of her husband.
For a totally scientific glimpse of the true nature that the planet Jupiter hides under the thick atmosphere of clouds which it shows to our telescopes, on 4 July, the Juno spacecraft penetrated the orbit of the fifth planet of the Solar System. During the mission, the spacecraft will enter a polar orbit and gravitate around the planet as much as 32 times, once every 11 days, at an altitude of almost 5000 km; during the flyby, Juno will examine Jupiter through the thick mantle of clouds covering it.
The NASA spacecraft was launched on 5 August 2011 aboard an Atlas V rocket from the Cape Canaveral Air Force Station in Florida, and the mission will end in 2017.
The scientific data that it will provide us with on gravitational and magnetic fields, atmospheric composition, temperature profile and wind speed, cloud opacity and magnetosphere of the poles, will be available with accuracy and depth greater than those achieved by the Galileo spacecraft (which reached the planet in December 1995) and will be very useful for understanding the auroras, structure, atmosphere and magnetosphere of the giant gaseous planet.
Once at its destination, Juno will reach the distance of 832 million kilometres from the Sun, a record for a spacecraft powered only by solar energy. Previously, the record was held by the European spacecraft Rosetta which, in October 2012, reached the distance of 792 million kilometres from the Sun during its approach to the comet 67P/Churyumov-Gerasimenko (to learn more: “Rosetta and Philae, out to discover new comets“).
Italy has made an important technological and scientific contribution to the mission by providing two of the ten instruments on board Juno: the JIRAM (Jovian InfraRed Auroral Mapper) infrared spectrometer to probe the upper layers of the atmosphere of Jupiter, built by the National Institute for Astrophysics (INAF) and by Selex-Galileo Avionica, and the KaT (Ka-Band Translator) radioscience instrument, built by Thales Alenia Space, to study the connections between gravitational field and mass distribution in the planet’s core.
There is not only Italian science in the hold of Juno: in addition to cutting-edge scientific instruments, the spacecraft has an aluminium plaque on board dedicated to the Italian genius, now part of the global culture, Galileo Galilei, in memory of his contribution to the knowledge of the giant planet and of the Solar System.
The plaque, provided by the Italian Space Agency (ASI), is a copy of the original manuscript in which Galileo Galilei, in 1610 (400 years ago), for the first time described the four moons of Jupiter (Io, Europa, Ganymede and Callisto). The discovery certainly represented a turning point in favour of the Copernican system, as well as in the use of instruments such as the telescope.
In addition, in a joint scientific outreach project for toddlers in order to attract children’s curiosity towards science, aboard the Juno spacecraft are three aluminium LEGO “men”, representing in a stylized manner the same number of imaginary characters in this mission. The first two are mythological: the god Jupiter, represented with a bolt of lightning under his arm, and his wife Juno, holding a mirror, symbol of the search for truth. The third character is real and is Galileo Galilei, represented with the planet Jupiter in one hand and the inseparable telescope in the other.
By Enzo Scasciamacchia