Juno’s unprecedented observations of Jupiter and its moons are a gift that keeps on giving.
The NASA spacecraft was originally scheduled to end its mission in 2018 after completing 34 orbits around the giant planet. It’s on track 47 now. How soon scientists will get a front-row view of these worlds is unclear, especially as spacecraft get closer to the powerful, damaging radiation from the gas giant and its magnetosphere.
But Juno will be difficult, space physicist Scott Bolton, Juno’s principal investigator, said during a Dec. 14 news conference at the American Geophysical Union’s fall meeting in Chicago. The spacecraft is “built like an armored tank, with its shields fixed,” said Bolton of the San Antonio-based Southwest Research Institute.
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After entering an expansive orbit around Jupiter in 2016, images from Juno quickly began helping scientists unravel the planet’s mysteries, including A geometric array of cyclones surrounding its poles and The strange and complex shape of its magnetic field (SN: 3/7/18; Serial Number: 9/5/18). Juno discovered Lightning storm sweeps over mountaintops planet’s clouds, and revealed that Jupiter is the only planet other than Earth known to host short-lived life, atmospheric glow from lightning known as elves and elves (Serial Number: 8/5/20; Serial Number: 11/2/20).
Juno has also passed by some of the planet’s moons, passing Ganymede in 2021. Ganymede is “bathed in Jupiter’s magnetic field,” and Juno was able to observe the tug-of-war of magnetic field lines between the planet and Ganymede, among other things. Its moon, says space physicist Thomas Greathouse, also of the Southwest Research Institute.
In September, Juno’s flyby of Jupiter’s moon Europa captured in new detail the chaotic intersection of cracks, ridges and bands on the lunar ice. Now the spacecraft is heading to the innermost moon Io.
While Juno appears to be going strong, “the end could come in two different ways,” Bolton said. Juno may become too degraded by the intense radiation to operate — or it may simply have run out of propellant, which is needed to keep its antenna pointed at Earth. If that happens, “it may be collecting data but not being able to send it back.”