Hello old friend! This week the Juno mission to the Jupiter system made the first close flyby of Jupiter’s giant moon Ganymede, and as you can imagine, the images are spectacular. This is the first time since the Galileo mission 20 years ago that we have seen the largest moon in the solar system up close. Voyager gave us the first views of Ganymede 40 years ago. Planetary researchers can now observe all changes in the surface of Ganymede over time.
But first the image editing gurus on earth try out the raw images sent back by Juno. Our main picture is from Gerald Eichstädt who used his magic to bring out the details of Ganymede and it is awesome.
“This is the next spacecraft that has come closest to this mammoth moon in a generation,” said Juno Principal Investigator Scott Bolton of the Southwest Research Institute in a press release. “We’ll take our time before drawing any scientific conclusions, but until then we can just marvel at this heavenly miracle.”
The pictures were taken on June 7, 2021 when Juno swung past Ganymede. One image comes from the JunoCam imager of the Jupiter orbiter and the other from its navigation camera, the Stellar Reference Unit. Both images show the surface in remarkable detail, including craters, clearly distinguished dark and light terrain, and long structural features possibly associated with tectonic faults.
This image of the dark side of Ganymede was captured by Juno’s Stellar Reference Unit navigational camera during its moon flyby on June 7, 2021. Photo credit: NASA / JPL-Caltech / SwRI
“The conditions under which we took the dark side image of Ganymede were ideal for a low-light camera like our Stellar Reference Unit,” said Heidi Becker, Junos Head of Radiation Monitoring at JPL. “So this is a different part of the surface than the JunoCam sees in direct sunlight. It will be fun to see what the two teams can put together. “
Detailed view of Ganymede from the JunoCam. Recognition: NASA / SwRI / MSSS / Alessandro G. Ceretti.
The surface of Ganymede has numerous central pit craters, which are complex craters that either have depressions in their floors or central elevations. Although these craters are from impacts, the formation of these central pits – and why they look like them – is not well understood. But the high content of volatile substances such as water ice in the lunar crust should also play a role.
At over 5,150 km (3,200 miles) wide, Ganymede is larger than the planet Mercury and the only moon large enough to create its own magnetosphere – a bubble of magnetic fields that traps charged particles and deflects them away from the sun . For size comparison, the earth is 12,740 km (7,917 miles) in diameter and our moon is 1,738 km (1,080 miles) wide.
This pass over Ganymede is the first in a series of flybys over the Galilean moons of Jupiter. This is part of Juno’s new expanded mission. The probe’s main mission, which began in 2016, focused on the gas giant itself. But now Juno has made long, highly elliptical orbits around Jupiter, dipping close to the planet to collect data on the planet before expanding again swings above the planet’s harmful radiation, which threatens the spacecraft’s hardware if left too long.
NASA says the spacecraft will send more images from its Ganymede flyby in the coming days, with the raw images from JunoCam being made available here. The “amateur” picture editors are still working on the new pictures, so you should keep an eye on the newly edited picture page here, especially the uploads by Gerald Eichstadt to the Juno page and Kevin Gill’s Flickr page.
Ganymede seen from JunoCam. The image is derived from a raw PJ34 JunoCam image, decompanded, and linearly stretched to remove darkness and moderate contrast. Subtle blurring and sharpening were used to improve the perception of details a little. Recognition: NASA / JPL / SwRI / MSSS / Gerald Eichstädt