“NASA did it again,” Scott Bolton, Juno’s principal investigator, said at a press conference at NASA’s Jet Propulsion Laboratory after insertion. His declaration was met with loud cheers and applause from media and others in attendance at the center in Pasadena, California.


The orbit insertion was a bit of a nail biter for NASA, as the spacecraft had to travel through regions of powerful radiation and rings of debris surrounding Jupiter. As an added precaution, the probe’s instruments were turned off for the maneuver so that nothing would interfere with the engine burn. But everything seemed to work flawlessly, and NASA received confirmation of the burn’s success almost exactly as expected. The timing only differed by 1 second from pre-burn predictions.

“Tonight through tones, Juno sang to us,” said Rick Nybakken, Juno’s project manager at NASA’s JPL, at the press conference. “And it was a song of perfection.” Nybakken even ripped up the mission team’s contingency communications plans that would have been needed in case something went wrong.

NASA received confirmation of insertion 48 minutes after the event actually occurred, though. That’s because it currently takes 48 minutes to send a signal from Jupiter to Earth. Juno started its burn at around 10:30PM ET and finished at 11:05PM ET, but NASA didn’t confirm all of this until just before midnight. If something had gone wrong and stopped the burn too early, the space agency wouldn’t have been in a position to fix the problem.

But now, Juno is in a highly elliptical orbit around Jupiter that takes 53 days to complete. For most of that orbit, the spacecraft will be far out from Jupiter, avoiding its intense radiation belts and debris field. But at the end of the 53-day cycle, Juno will swing back close to the planet again. During this close pass, the vehicle will first fly over the north pole and then swoop in close over Jupiter’s equator — squeezing in between the radiation belts and the planet’s surface. Juno then swings back out into space over the planet’s south pole.


This whole sequence of events, known as the Perijove pass, will take just a few hours to complete. But it’s during this time that Juno will conduct the most science over Jupiter. The spacecraft’s onboard instruments will be measuring the amount of water in Jupiter’s atmosphere, as well as the planet’s gravity and magnetic field. These measurements will help NASA figure out if Jupiter has a dense core underneath its surface. All of these details can be used to piece together exactly how and when Jupiter formed more than 4 billion years ago.

Initially, Juno will complete two of these 53-day orbits. Its first big Perijove pass — when all of the spacecraft’s instruments are turned on — will occur on August 27th. During Juno’s second swing by Jupiter on October 19th, the probe will light its main engine again, putting the vehicle in a shorter two-week orbit around the planet. Juno will then remain in this 14-day orbit until the end of its mission. Overall, the spacecraft is slated to complete 37 orbits around Jupiter before it dives to its death into the gassy planet.

Update July 5th 1:13AM ET: The article was updated to include statements from a NASA press conference.