Juno is the first solar-powered space probe sent to investigate our solar system’s largest planet. A better knowledge of Jupiter will help astronomers understand the large planets now being discovered orbiting other stars.
Juno's mission is to enter a polar orbit of Jupiter and spend up to a year studying Jupiter’s deep structure, mapping the planet’s gravity and magnetic fields.
Instruments aboard the probe will measure water content in the atmosphere to find clues about how the planet formed. It will also sample auroras, electric fields, plasma waves and particles in Jupiter’s environment.
In the first 30 years of space exploration, deep space probes used nuclear power generators to provide sufficient electricity for operating in the cold and dark outer solar system beyond Mars. In the 21st century, solar power technology has improved enough to make the panels suitable for use on these spacecraft.
Jupiter exerts a powerful magnetic field that traps radiation in a thick belt around the planet. To avoid frying its electronic equipment, Juno takes a path that bypasses the most intense areas of the radiation belt.
Juno is the ninth probe from Earth sent to Jupiter, and only the second probe to orbit the planet.