On December 30, NASA's Juno snapped this image of Jupiter's moon Io.
Update, Jan. 1, 2024: Six spectacular color images of Io have now been published by NASA.
NASA’s spacecraft Juno just had a super-close encounter with the most volcanic world in the solar system—but its stunning first image could be among its last after 56 orbits of Jupiter.
On December 30, the bus-sized spacecraft—orbiting Jupiter since 2016—got very close to Io, the giant moon of Jupiter. It reached a mere 930 miles (1,500 kilometers) from the moon’s surface. However, the spacecraft’s camera has suffered radiation damage and may not last much longer.
First Image
The first image to come back from this, the closest pass since NASA’s Galileo probe imaged the volcanic moon in October 2001, was published on social media by NASA on December 31. “The JunoCam instrument aboard our Juno Mission acquired six images of Jupiter's moon Io during its close encounter today," read the tweet. "This black-and-white view was taken at an altitude of about 1,500 miles (2,500 kilometers).”
If you look carefully, the dark side of Io is also visible. It's lit up by "Jupitershine"—sunlight reflecting from Jupiter onto Io.
More Images Incoming
It promised that more images of Io—and of Jupiter itself—will be available soon from the mission's image website. The space agency typically uploads a tranche of data from Juno via its Deep Space Network shortly after each close pass it makes of Jupiter.
This black-and-white view, taken through JunoCam's red filter, shows Io's high northern latitudes. The images are four times more detailed than those Juno took in October, which were the best for 22 years.
The moon's turbulent 42-hour orbit of Jupiter produces immense heat, which scientists think creates an ocean of magma under its rocky surface. Io is the most volcanic world in the solar system, with eruptions orders of magnitude bigger than anything similar on Earth.
Moon Tour
Since 2016, Juno has been exploring Jupiter and its four largest moons. It has flown very close to three of these moons—Europa, Ganymede and Io. The fourth moon, Callisto, will be visited by another spacecraft called JUICE multiple times between July 2031 and December 2034. JUICE will also visit Europa and Ganymede and stay in orbit around Ganymede.
Another spacecraft called Europa Clipper will focus on exploring Europa and will be touring Jupiter's moons starting in 2030. However, there are no plans to visit Io—so what Juno sends us later this week will be crucial.
Juno will be making another close pass by Io in February, so expect some incredible images from NASA in the next few months. At least, that’s the plan.
Radiation Damage
Accompanying this spectacular image is a strong hint from NASA that JunoCam may be coming towards the end of its life. Originally designed to last only a handful of orbits, it’s recently been suffering from overheating.
“After Juno’s last close pass by Jupiter in November, JunoCam's performance was severely degraded by radiation damage,” wrote NASA on Facebook. “Using its built-in heater, the camera was warmed to a temperature of about 65 degrees Celsius (150 degrees Fahrenheit) for several weeks in December, a process called ‘annealing,’ and this treatment has restored camera function, at least for this pass.”
Wishing you clear skies and wide eyes.
