While across America people are lighting off fireworks, the Juno probe will quietly be launching some of its own. At 10:18 PM Central Daylight Time*, Juno will light its main engine for thirty-five minutes, dropping speed just precisely enough to be captured in Jupiter’s massive gravity well. The spacecraft will consume an impressive 7,900 kg of hydrazine and nitrogen tetroxide bipropellant during this maneuver using its British-built LEROS 1b main engine. While the burn happens, the spacecraft will not be able to point its high-gain antenna directly at Earth; mission controllers will therefore only have a carrier signal to go on to judge its progress. They will monitor the Doppler effect on this signal to see the change in Juno’s velocity. You will know if it’s been successful if you see a lot of people jumping and shouting and cheering. 😉
*More properly, we’ll know about the engine burn starting at 10:18 PM. Since we’re presently about 48 light-minutes from Jupiter, by the time the signal arrives telling controllers that the burn has started, it will already be over. Everything on a deep space mission is experienced as the signal arrives at Earth, not the time it actually happens across the solar system.