NASA has put a spacecraft into orbit around Jupiter.

Around 10:30 p.m. on Monday, Juno passed over Jupiter’s north pole and through a region that Heidi Becker, the leader of Juno’s radiation monitoring team, described as “the scariest part of the scariest place.” In this belt of radiation, electrons bouncing back and forth at nearly the speed of light could have knocked out the computer and other electronics.

“They will go right through a spacecraft and strip the atoms apart inside your electronics and fry your brain if you don’t do anything about it,” Dr. Becker said.

But a titanium vault built for Juno proved up to the task of shielding its crucial systems.

Someone in a NASA video pointed out that Jupiter has a bunch of moons in different orbits traveling at different speeds, and picking your way through all that is [understatement] a challenge.

At 11:18 p.m., Juno’s main engine began firing to slow the spacecraft enough to be captured by the planet’s gravity. Juno also passed through the plane of Jupiter’s diaphanous rings. Although the mission planners had chosen a place that they thought would be clear, they could not be certain, and even a piece of dust colliding with a spacecraft moving at 130,000 m.p.h. could have caused considerable damage.

Juno traveled within 2,900 miles of Jupiter’s cloud tops, passing through almost the exact spot that the navigators had aimed for after its 1.7-billion-mile voyage. “Isn’t that incredible?” Mr. Nybakken said.

It is. It is.

The spacecraft will have to make multiple flybys, Dr. Bolton said, before the scientists will be able to start answering questions like whether there is a rocky core at the center of Jupiter. “We’ll be hesitant to guessing the wrong answer until we see more information,” Dr. Bolton said.

With a different vantage point from Juno’s polar orbit, the spacecraft’s cameras are likely to add to the number of known moons of Jupiter, now 67. “I expect that we will see some, and the number will keep going up,” Dr. Bolton said.

Radiation will gradually fry the instruments, and on the 37th orbit Juno will do a suicide dive into Jupiter, in order to avoid contaminating Europa with earthly microbes.