Once it reaches Jupiter the Juno spacecraft, launched Aug. 5, 2011, 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, JPL said.
It reached the halfway point on its mission at 8:25 a.m. EDT.
"Juno's odometer just clicked over to 9.464 astronomical units," Juno Principal Investigator Scott Bolton of the Southwest Research Institute in San Antonio said. "The team is looking forward, preparing for the day we enter orbit around the most massive planet in our solar system."
An astronomical unit, or AU, is the distance between Earth and the sun -- 92,955,807.273 miles -- and is a unit of measure often used by space engineers and scientists when discussing the massive distances involved in the exploration of our solar system.
The 9.464 astronomical units Juno has traveled to date -- and has ahead of it -- is equivalent to 879,733,760 miles.
In October, Juno will fly past Earth in search of a little extra speed.
"On Oct. 9, Juno will come within 347 miles of Earth," mission Project Manager Rick Nybakken of JPL said. "The Earth flyby will give Juno a kick in the pants, boosting its velocity by 16,330 mph. From there, it's next stop Jupiter."
Juno is set to arrive at Jupiter on July 4, 2016.