Juno completes 3rd orbit, captures ‘pearl’
Streaking by at about 129,000 mph (57.8 kilometers per second), NASA’s Juno spacecraft completed its third flyby some 2,580 miles (4,150 kilometers) over Jupiter’s cloud tops. The close approach occurred at 12:04 a.m. EST (17:04 GMT) Dec. 11, 2016.
This was Juno’s third close approach – called perijove – since the spacecraft was captured into a 53-day orbit around the gas giant back on July 4, 2016. However, this was the first time the spacecraft operated in its full capacity to investigate Jupiter’s interior structure via its gravity field.
“We are looking forward to what Jupiter’s gravity may reveal about the gas giant’s past and its future,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio, in a news release before the flyby.
Seven of Juno’s eight science instruments were collecting data during the flyby. Mission managers decided to not use the Jovian Infrared Auroral Mapper instrument during this approach. This was to allow the science team to complete an update to the software that processes the instrument. That patch is expected to be completed before the next perijove pass on Feb. 2, 2017.
A ninth – instrument not a mission science instrument, rather a public outreach camera – was also active for this flyby. The JunoCam imager took a picture of the seventh of eight features that form a “string of pearls” on Jupiter. The massive counterclockwise rotating storms appear as white ovals in the southern hemisphere of the gas giant. According to NASA, since 1986, these ovals have numbered from six to nine, with only eight visible today.
When JunoCam took the picture, the spacecraft was 15,300 miles (24,600 kilometers) from the planet.
Juno’s orbital period
While Juno is currently in a 53-day orbit, it was expected the spacecraft was to have reduced its orbit to only 14 days by October. However, in the days leading up to the planned Oct. 19 maneuver, telemetry showed the probe’s helium valves were not opening properly. It was decided to postpone the burn to the Dec. 11 perijove, but that too was canceled to allow the team more time to weigh options.
“We have a healthy spacecraft that is performing its mission admirably, and we are able to obtain great science every time we fly by,” said Rick Nybakken, project manager for Juno from NASA’s Jet Propulsion Laboratory in Pasadena, California. “What we do not want to do is add any unnecessary risk, so we are moving forward carefully.”
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity.