NASA's Juno mission, launched August 5, 2011, is now just a few weeks and about 17.8 million km (11.1 million miles) away from Jupiter, the largest planet in our solar system. Its mission team is using these last weeks to evaluate and re-evaluate every portion of the Jupiter orbit insertion (JOI) process, finding very low probability events and running them to ground.
Juno's arrival at Jupiter is expected around 05:30 UTC on July 5, 2016 (Earth Received Time), when the spacecraft will fire its main engine for 35 minutes, in an attempt to place it into a polar orbit around the gas giant. As NASA points out, "it will be a daring planetary encounter: Giant Jupiter lies in the harshest radiation environment known, and Juno has been specially designed to safely navigate the brand new territory."
Once in orbit, the spacecraft will circle the Jovian world 37 times, skimming to within 5 000 km (3 100 miles) above the planet's cloud tops. During the flybys, Juno will probe beneath the obscuring cloud cover of Jupiter and study its auroras to learn more about the planet's origins, structure, atmosphere and magnetosphere.
Scott Bolton, the principal investigator for Juno from the Southwest Research Institute in San Antonio, said the spacecraft is closing the distance between us and Jupiter at about 23 000 km/h (14 400 mph or 4 mps). "But Jupiter's gravity is tugging at us harder every day and by the time our rocket engine puts on the brakes to get us into orbit, we'll be accelerated to 10 times that speed - to nearly 230 000 km/h (70 km/s, more than 40 miles per second)."
"We are in the last test and review phases of the JOI sequence as part of our final preparations for Jupiter orbit insertion," said Rick Nybakken, project manager of Juno for NASA's Jet Propulsion Laboratory in Pasadena, California. "Throughout the project, including operations, our review process has looked for the likely, the unlikely and then the very unlikely. Now we are looking at extremely unlikely events that orbit insertion could throw at us."
The Juno mission is the second spacecraft designed under NASA's New Frontiers Program. The first is the Pluto New Horizons mission, which flew by the dwarf planet in July 2015 after a nine-and-a-half-year flight. The program provides opportunities to carry out several medium-class missions identified as top priority objectives in the Decadal Solar System Exploration Survey, conducted by the Space Studies Board of the National Research Council in Washington.
Juno’s onboard color camera, called JunoCam, invites the public to serve as a virtual imaging team. Vote and comment on where to point JunoCam and which features to image on Jupiter using the new JunoCam web platform on this site.
Juno's name comes from Greek and Roman mythology. The mythical god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife - the goddess Juno - was able to peer through the clouds and reveal Jupiter's true nature.
Featured image: artist's rendering shows NASA's Juno spacecraft making one of its close passes over Jupiter. Image credit: NASA/JPL-Caltech