Juno Hours from Gas Giant Jupiter
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.
During its mission of exploration, Juno will circle the Jovian world 37 times, soaring low over the planet’s cloud tops — as close as about 2,600 miles (4,100 kilometers). During these flybys, Juno will probe beneath the obscuring cloud cover of Jupiter and study its auroras to learn more about the planet’s origins, structure, atmosphere and magnetosphere.
Juno’s name comes from Greek and Roman mythology. The mythical god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife — the goddess Juno — was able to peer through the clouds and reveal Jupiter’s true nature.
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JPL manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for NASA’s Science Mission Directorate in Washington. Lockheed Martin Space Systems, Denver, built the spacecraft. The California Institute of Technology in Pasadena manages JPL for NASA.
