Success! The Juno spacecraft is now orbiting Jupiter

On July 4, NASA’s Juno probe arrived safely at Jupiter. The spacecraft traveled for nearly five years and 2.8 billion kilometers (1.74 million miles) through space. Its mission? To investigate the gas giant’s deep interior.

Researchers want to know everything they can about what lies beneath the planet’s blanket of clouds. Juno’s instruments will help them find out how much water vapor is hiding there. They will map the planet’s internal structure. And they will probe Jupiter’s vast magnetic field while looking at its polar regions.

Juno is the ninth spacecraft to visit the largest planet in our solar system. It’s the second to orbit it. And it will now spend 20 months circling Jupiter before diving to its death into the massive planet’s depths.

During its approach, Juno came within 76,000 kilometers (47,000 miles) of the tops of Jupiter’s clouds. (That’s about one-fifth the distance between Earth and our moon.) At 11:05 p.m., the spacecraft completed a 35-minute firing of its main engine. This helped Juno slow down to about 209,000 kilometers per hour (130,000 miles per hour). The decreased speed allowed the probe to be captured by Jupiter’s gravity and slip into orbit around it.

Juno wasn’t able to take pictures to celebrate its arrival. That’s because all of its scientific instruments were switched off on June 29. Otherwise, the delicate equipment could have been damaged when the probe flew through the planet’s strong radiation field. Scientists won’t get an intimate look at their target until August 27. That’s when Juno will swoop in again with all of its instruments turned on.

From here, Juno will make a 53-day loop around Jupiter that will end in October. Then it will begin a series of 14-day orbits. These will take the spacecraft above the planet’s north and south poles, soaring just 5,000 kilometers (3,100 miles) above the tops of the planet’s stormy clouds.

“What a feeling,” said Geoffrey Yoder, after learning that Juno had arrived safely. He’s the acting associate administrator of NASA’s division overseeing science missions, in Washington, D.C. “A mission of this complexity, to accomplish tonight, is just truly amazing.”

Rick Nybakken is Juno’s project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Tonight, through tones, Juno sang to us,” he noted on the orbiter’s arrival. “And it was a song of perfection.”