On July 4th, NASA’s Juno spacecraft is scheduled to enter into orbit of the solar system’s largest planet, Jupiter, completing a near five-year journey toward the unknown – and embarking onto its next unprecedented mission.

Here, we break down everything you need to know about Juno’s journey so far, what’s going to happen on Monday and how this knowledge has the potential to change everything we understand about the solar system.


Firstly, it’s important to understand the severity of Jupiter and just how (literally) massive this challenge is.

Jupiter is, by far, the largest planet in the solar system – so big you could fit over a thousand Earths inside it. It’s 300 times the mass of Earth and about two-thirds the size of all the planets in the solar system put together.

Jupiter’s high quantity of liquid metallic hydrogen means it is buried under the solar system’s largest magnetic field, with pressures up to 2 million times the pressure on Earth, and the most severe radiation environment of anybody in the solar system – other than the sun.

The background radiation we’re exposed to on Earth is about 0.39 of a RAD, while Juno is expected to experience about 20 million RAD over the course of its mission.


A mission of firsts, Juno is the fastest spacecraft to ever venture into the solar system, is the first space mission to operate a solar-powered spacecraft, will be the first to fly close to Jupiter and will be the first to orbit an outer-planet from pole to pole.

Launched on August 5, 2011, on a mission that cost $1.13 billion, Juno has had quite the journey so far.

It went in orbit around the sun at first, passed the orbit of Mars before a couple of main engine blasts fired the spacecraft back toward Earth where it got a gravity assist to set it on a 445 million mile course to Jupiter.

Juno will arrive at Jupiter on Monday, July 4th (for NASA), and the Jupiter Orbit Insertion burn begins at 8:18pm Pacific Daylight Time (PDT) and will last approximately 35 minutes.

When Juno has fulfilled its purpose, the spacecraft is scheduled to plunge itself into Jupiter’s atmosphere in February 2018.


The most dangerous part of the mission will be when Juno first enters Jupiter’s orbit, aka Jupiter Orbit Insertion.

Jupiter’s pressure is far too high to simply drop a probe on its surface, and so NASA’s plan is to thread a fine line by getting as close as possible to the planet, without getting sucked in by Jupiter’s magnetic field.

Juno will fly as close as 2,600 miles from Jupiter’s cloud tops, an area referred to as the “safe zone,” and then circle far away before coming back to loop around the planet again, a route that will take 14 days.

Juno will repeat that same loop every two weeks for about a year and a half until it has collected data from all over the entire planet.

Each time Juno flies close to Jupiter’s cloud tops it will turn on its measuring instruments to collect a range of data about the planet, including the highest-resolution images ever taken of Jupiter.


Jupiter is the first planet formed so any information learned from the Juno mission is going to shed light on the early history of the solar system in way they can’t learn from other planets.

Scientists hope to gain an understanding of how the solar system was born from analyzing Jupiter’s interior, and they also want to know things like how magnetic fields are generated by getting the first unobstructed view into Jupiter’s core.


NASA TV coverage begins at 10:30pm Eastern Daylight Time.

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