Juno enters orbit around Jupiter

Juno enters orbit around Jupiter

NASA's Juno spacecraft has successfully entered Jupiter's orbit during a 35-minute engine burn on July 5, 2016 (UTC). The confirmation that the burn had completed was received on Earth at 03:53 UTC (Earth-receive time, currently 48 minutes after the actual event). Diane Brown, Juno program executive at NASA, said the orbital insertion was “flawless.”

“This is the one time I don’t mind being stuck in a windowless room on the night of the 4th of July,” said Scott Bolton, principal investigator of Juno from Southwest Research Institute in San Antonio. “The mission team did great. The spacecraft did great. We are looking great. It’s a great day.”

The Juno team celebrates at NASA’s Jet Propulsion Laboratory in Pasadena, California, after receiving data indicating that NASA’s Juno mission entered orbit around Jupiter. Rick Nybakken, Juno project manager at JPL, is seen at the center hugging JPL's acting director for solar system exploration, Richard Cook. Credit: NASA/JPL-Caltech

The spacecraft has crossed the boundary of Jupiter's immense magnetic field on June 24, 2016. Its Waves instrument recorded the encounter with the bow shock over the course of about two hours.

"Bow shock" is where the supersonic solar wind is heated and slowed by Jupiter's magnetosphere. It is analogous to a sonic boom on Earth.

The next day, June 25, the Waves instrument witnessed the crossing of the magnetopause. "Trapped continuum radiation" refers to waves trapped in a low-density cavity in Jupiter's magnetosphere. 

Preplanned events leading up to the orbital insertion engine burn included changing the spacecraft’s attitude to point the main engine in the desired direction and then increasing the spacecraft’s rotation rate from 2 to 5 revolutions per minute (RPM) to help stabilize it.

The burn of Juno’s 645-Newton Leros-1b main engine began on time at 03:18 UTC (Earth-receive time, 48 minutes after the actual event), decreasing the spacecraft’s velocity by 542 meters per second (1 212 mph) and allowing Juno to be captured in orbit around Jupiter. Soon after the burn was completed, Juno turned so that the Sun’s rays could once again reach the 18 698 individual solar cells that give Juno its energy.

“Jupiter orbit insertion was a big step and the most challenging remaining in our mission plan, but there are others that have to occur before we can give the science team the mission they are looking for,"  said Rick Nybakken, Juno project manager from JPL.

During it’s final approach to Jupiter, NASA’s Juno spacecraft captured this unique time-lapse movie of the Galilean satellites in motion about the planet. The movie begins with images taken on June 12th when Juno was 16 million km (10 million miles) from Jupiter, and ends on June 29th, at 4.8 million km (3 million miles) distant. The innermost moon is volcanic Io; next in line is the ice-crusted ocean world Europa, followed by massive Ganymede, and finally, heavily cratered Callisto.

Over the next few months, Juno’s mission and science teams will perform final testing on the spacecraft’s subsystems, final calibration of science instruments and some science collection.

Juno's principal goal is to understand the origin and evolution of Jupiter. The spacecraft will look for solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe Jupiter's auroras. 

The official science collection phase begins in October, but the mission managers figured out a way to collect data a lot earlier than that.

The mission also will let us take a giant step forward in our understanding of how giant planets form and the role these titans played in putting together the rest of the solar system. As our primary example of a giant planet, Jupiter also can provide critical knowledge for understanding the planetary systems being discovered around other stars.

Juno starts its tour of Jupiter in a 53.5-day orbit. The spacecraft saves fuel by executing a burn that places it in a capture orbit with a 53.5-day orbit instead of going directly for the 14-day orbit that will occur during the mission's primary science collection period. The 14-day science orbit phase will begin after the final burn of the mission for Juno’s main engine on October 19.

Juno is solar-powered spacecraft, launched on August 5, 2011 from Cape Canaveral Air Force Station in Florida. Its mission at Jupiter will end with an intentional death dive in February 2018.

Featured image credit: This illustration depicts NASA's Juno spacecraft successfully entering Jupiter's orbit. Credit: NASA/JPL-Caltech

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