Juno is a NASA New Frontiers mission currently orbiting the planet Jupiter. Juno was launched from Cape Canaveral Air Force Station on August 5, 2011 and arrived on July 4, 2016. The spacecraft is in a polar orbit to study Jupiter’s composition, gravity field, magnetic field, and polar magnetosphere. Juno will also search for clues about how the planet formed, including whether it has a rocky core, the amount of water present within the deep atmosphere, mass distribution, and its deep winds, which can reach speeds of 618 kilometers per hour (384 mph).
Juno is the second spacecraft to orbit Jupiter, following the Galileo probe which orbited from 1995–2003.
The Juno spacecraft is powered by solar arrays, commonly used by satellites orbiting Earth and working in the inner Solar System, whereas radioisotope thermoelectric generators are commonly used for missions to the outer Solar System and beyond. For Juno, however, three solar array wings, the largest ever deployed on a planetary probe, will play an integral role in stabilizing the spacecraft and generating power.
The spacecraft’s name comes from Greco-Roman mythology. The god Jupiter drew a veil of clouds around himself to hide his mischief, but his wife, the goddess Juno, was able to peer through the clouds and see Jupiter’s true nature. The mission had previously been referred to by the backronym JUpiter Near-polar Orbiter in a list of NASA acronyms.
What is the Juno mission for?
Scientists are trying to solve the mystery of what lies beneath the swirling storm clouds of Jupiter.
Little is known about the huge gas giant which is so big it can be seen from Earth without a telescope, and which produces the most spectacular auroras in the solar system.
Scientists are not even sure if there is a solid core beneath its turbulent atmosphere or what drives the enormous magnetic field which surrounds the planet. If the invisible magnetosphere glowed in visible light, it would appear twice the size of the full Moon from Earth.
What’s so special about Juno?
The Juno spacecraft is packed with nine instruments capable of peering into the planet’s heart. It will fly 2,600 miles above the cloud tops – 3,000 miles closer to the surface than any other mission has ever achieved. Juno is the first mission to Jupiter to use solar panels instead of the radioisotope thermoelectric generators (RTG) used by Pioneer 10, Pioneer 11, the Voyager program, Ulysses, Cassini–Huygens, New Horizons, and the Galileo orbiter. It is also the farthest solar-powered trip in the history of space exploration.
The Juno spacecraft uses three solar panels symmetrically arranged around the spacecraft. Shortly after it cleared Earth’s atmosphere the panels were deployed. Two of the panels have four hinged segments each, and the third panel has three segments and a magnetometer. Each panel is 2.7 meters (8.9 ft) by 8.9 meters (29 ft) long,with a total area of 60 m2 the second biggest on any deep-space probe only surpassed by Rosetta‘s 64 m2
The Juno spacecraft’s suite of science instruments will:
- Determine the ratio of oxygen to hydrogen, effectively measuring the abundance of water in Jupiter, which will help distinguish among prevailing theories linking Jupiter’s formation to the Solar System.
- Obtain a better estimate of Jupiter’s core mass, which will also help distinguish among prevailing theories linking Jupiter’s formation to the Solar System.
- Precisely map Jupiter’s gravitational field to assess the distribution of mass in Jupiter’s interior, including properties of its structure and dynamics.
- Precisely map Jupiter’s magnetic field to assess the origin and structure of the field and how deep in Jupiter the magnetic field is created. This experiment will also help scientists understand the fundamental physics of dynamo theory.
- Map the variation in atmospheric composition, temperature, structure, cloud opacity and dynamics to pressures far greater than 100 bars(10 MPa; 1450 pound/sq inch) at all latitudes.
- Characterize and explore the three-dimensional structure of Jupiter’s polar magnetosphere and its auroras.
- Measure the orbital frame-dragging, known also as Lense–Thirring precession caused by the angular momentum of Jupiter, and possibly a new test of general relativity effects connected with the Jovian rotation.
What scientists hope to learn?
Jupiter is the first planet formed, so any information learned from the Juno mission could shed light on the solar system’s early history in a way they can’t learn it from other planets.
Scientists hope to gain an understanding of how our system was born by analyzing Jupiter’s interior – and they also want to know things like how magnetic fields are generated by getting the first unobstructed view into Jupiter’s core.
NASA received data from the spacecraft to confirm that it has completed its orbit insertion burn and is now officially in Jupiter orbit.