After a five-year voyage across 1.8bn miles (2.8bn km), Nasa’s Juno spacecraft has reached Jupiter and quietly positioned herself in its orbit at 03.18 GMT. The final manoeuvres were extremely complex, considering the distance and the time for the impulse to travel to Earth and back to the spacecraft, switching off its engines and then starting them again to enter at exactly the right moment. Juno did spin down from its current five rotations per minute, to two and then it will turn around to face the sun, so that it can recharge its batteries. After that it will switch on its main antenna, and start again communicating with Earth.
This is an extraordinary success for the United States’ space technology and for Jennifer Delavan of Lockheed Martin, who built Juno.
We can also imagine Galileo Galilei cheering with the scientists 404 years after he discovered, using his telescope, that some of the stars close to Jupiter weren’t moving as expected. In January 1610 he figured out that they were actually orbiting moons, just like our moon orbiting around our planet. He called them Medicean Moons to honour the family of rulers of Tuscany. The Galilean moons are the four largest moons of Jupiter: Io, Europa, Ganymede, and Callisto. Their names come from lovers of Zeus with Ganymede being the largest moon in the Solar System, even bigger than the planet Mercury.
There is also something Italian on Juno, besides Galileo’s spirit: a infrared spectrophotometer JIRAM (Jovian InfraRed Auroral Mapper) – produced by Leonardo-Finmeccanica under the supervision of the National institute of Astrophysics (INAF) – and the KaT instrument (Ka-Band
Translator), produced by Thales Alenia Space in collaboration with La Sapienza University of Rome. These instruments were conceived and built using the experience accumulated during the VenusExpress mission around Venus; the Cassini mission around Saturn and the Rosetta on the Churyumov-Gerasimenko.