NASA’s Juno spacecraft is set to arrive in Jupiter’s orbit on July 4, when it will get “closer than any spacecraft” before it, NASA said this week. It won’t be easy, though. In fact, NASA considers getting Juno into orbit a trial of its own — not to mention the trip it took to get there.

NASA explained that there are so many unknowns about Jupiter, particularly the gassy environment. “Nothing is really certain about what’s going to happen,” one NASA employee said of the approach. Keep in mind, too, that this day has been many years in the making. Juno first launched from Earth back in 2011. “It’s a monster,” another NASA employee said of Jupiter. “It’s unforgiving, it’s relentless, it’s spinning around so fast its gravity is like a giant slingshot slinging rocks, dust, electrons, whole comets, anything that gets close to it becomes its weapon.”

But NASA says there are secrets about the “early solar system” inside of Jupiter that we need. Humans need to understand Jupiter to understand more about us, about life, about the solar system we live in. This is the Jupiter Orbiter Insertion (JOI for short), and we’ll find out what happens on July 4.