NASA’s Juno Is Halfway to Jupiter

NASA’s Juno spacecraft reaches the halfway point on its long journey to Jupiter.

NASA’s Juno spacecraft is halfway to Jupiter. The spacecraft reached the milestone August 12 at 12:25 UTC.

“Juno’s odometer just clicked over to 9.464 astronomical units,” said Juno principal investigator Scott Bolton of the Southwest Research Institute in San Antonio. “The team is looking forward, preparing for the day we enter orbit around the most massive planet in our solar system.”

An astronomical unit is a unit of measure based on the distance between Earth and the sun and is 149,597,870.7 kilometers long. The 9.464 astronomical units Juno has already traveled, and still has left to go, are more than 1.4 billion kilometers. Juno was 55.46 million kilometers from Earth when the milestone was reached. The next milestone in the nearly five-year journey to Jupiter will occur in October, when the spacecraft flies past Earth in search of extra speed.

“On October 9, Juno will come within 347 miles [559 kilometers] of Earth,” said the mission’s project manager, Rick Nybakken of NASA’s Jet Propulsion Laboratory in Pasadena, California. “The Earth flyby will give Juno a kick in the pants, boosting its velocity by 16,330 mph [about 7.3 kilometers per second]. From there, it’s next stop Jupiter.”

Juno will arrive at Jupiter on July 4, 2016, at 7:29 p.m. in California (2:29 July 5 UTC).

Juno was launched on August 5, 2011. Once in orbit around Jupiter, the spacecraft will circle the planet 33 times, from pole to pole, and use its collection of eight science instruments to probe beneath the gas giant’s obscuring cloud cover. Juno’s science team will learn about Jupiter’s origins, structure, atmosphere and magnetosphere, and look for a potential solid planetary core.

The Italian Space Agency contributed an infrared instrument and a portion of the radio science experiment to the Juno mission.