After almost five years and 1.7 billion million miles (2.7 billion kilometers), NASA’s Juno mission is about to enter into orbit around the biggest planetary inhabitant in our solar system — Jupiter. Approaching the massive planet from above, Juno will be within 300,000 miles of Jupiter by 2:14 p.m. PDT (5:14 p.m. EDT). A minute later, Juno will cross the orbit of Jupiter’s innermost Galilean moon (Io), at 2:15 p.m. PDT (5:15 p.m. EDT). Juno closes the distance between it and the gas-giant world to 200,000 miles (322,000 kilometers) by 4:17 p.m. PDT (7:17 p.m. EDT) and is only 100,000 miles (161,000 kilometers) away by 6:03 p.m. PDT (9:03 p.m. EDT).
“As planned, we are deep in the gravity well of Jupiter and accelerating,” said Rick Nybakken, Juno project manager from NASA’s Jet Propulsion Laboratory in Pasadena, California. “Even after we begin firing our rocket motor, Jupiter will continue to pull us, making us go faster and faster until we reach the time of closest approach. The trick is, by the end of our burn, we will slow down just enough to get into the orbit we want.”
The burn is called Jupiter orbit insertion, or as they refer to it in the halls and offices of the Juno team, “JOI.” At 8:18 p.m. PDT (11:18 p.m. EDT), JOI will begin when Juno fires its main engine, beginning a 35-minute burn that imparts a mean change in velocity of 1,212 mph (542 meters per second) on the spacecraft. … (NASA)