Back in the early 2000s, scientists began planning how to design and build a spacecraft that could not only survive the voyage to Jupiter, but subsist in its hellish radiation environment long enough to make a careful study of the gas giant’s composition and its mysterious interior. For the spacecraft, the radiation dosage during the 1.5-year science mission is equivalent to a patient sitting in a dentist’s chair and being X-rayed every second of every day for three years.

Juno is now more than 850 million kilometers away from Earth. After all of that work, a spectacular launch and a deep space cruise, the fate of Juno comes down to tonight—can it successfully fall into orbit around the giant of the solar system?

Engineers at NASA’s Jet Propulsion Laboratory in California have already sent a command to the spacecraft to initiate its autopilot mode. This kicked off a software program that will culminate on Monday night when the spacecraft’s main engine, a Leros 1b built by Moog-ISP in England, fires for 35 minutes. That burn is scheduled to begin at 11:18pm ET (4:18am BST on July 5).