Following the speed-boosting slingshot maneuver around Earth that sent NASA’s Juno orbiter hurtling toward Jupiter on Wednesday, the probe has successfully transmitted back data and its first flyby images — even though it unexpectedly went into "safe mode" during the critical maneuver.
“Juno is transmitting telemetry today,” Guy Webster, a spokesman for NASA’s Jet Propulsion Laboratory, told Universe Today in a phone interview late Thursday.
The images of Earth captured by the Junocam imager proves that the spacecraft is communicating as it continues sailing on its 2.8 billion-kilometer (1.7 billion-mile) outbound trek to the Jovian system.
“Juno is still in safe mode,” Webster told Universe Today. "Teams at Mission Control at JPL and Lockheed Martin are actively working to bring Juno out of safe mode. And that could still require a few days."
Lockheed Martin is the prime contractor for Juno.
The initial raw images of Earth snapped by the craft’s Junocam imager were received by ground stations late Thursday.
Glitch with the gravity assist
Juno performed a crucial swing-by of Earth on Wednesday that accelerated the probe by 16,330 mph (26,280 km/h) to enable it to arrive in orbit around Jupiter on July 4, 2016.
However the gravity assist maneuver did not go entirely as planned.
Shortly after Wednesday’s flyby, Juno project manager Rick Nybakken, of JPL, told Universe Today that Juno had entered safe mode, but that the probe was “power-positive and we have full command ability."
“After Juno passed the period of Earth flyby closest approach at 12:21 p.m. PDT [3:21 p.m. ET] and we established communications 25 minutes later, we were in safe mode,” Nybakken explained. The safe mode was triggered while Juno was in an eclipse mode, the only eclipse it will experience during its entire mission.
The Earth flyby did accomplish its objective by placing the $1.1 Billion Juno spacecraft exactly on course for Jupiter as intended. “We are on our way to Jupiter as planned,” Nybakken said.
“None of this affected our trajectory or the gravity assist maneuver – which is what the Earth flyby is,” he said.
Closest approach over Africa
Juno’s closest approach was over South Africa at about 561 kilometers (349 miles).
During the flyby, the science team planned to observe Earth using most of Juno’s nine science instruments, since the slingshot also serves as a key test of the spacecraft systems and the flight operations teams. As it came in from Earth's sunlit side, Juno was also due to capture a movie of the Earth-moon system.
"During the Earth flyby we have most of our instruments on, and we'll obtain a unique movie of the Earth-moon system on our approach," said Juno principal investigator Scott Bolton, a researcher at the Southwest Research Institute. “We will also calibrate instuments and measure earth’s magnetosphere, obtain closeup images of the Earth and the moon in UV [ultraviolet] and IR [infrared]."
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Ken Kremer is a speaker, scientist, freelance science journalist and photographer in Princeton, N.J., whose articles, space exploration images and Mars mosaics have appeared in magazines and books, as well as on websites and calendars including Astronomy Picture of the Day and the covers of Aviation Week & Space Technology, Spaceflight and the Explorers Club magazines.
This is an edited version of a report originally published on Oct. 10 on Universe Today with the headline "NASA’s Juno Spacecraft Returns 1st Flyby Images of Earth While Sailing on to Jupiter."