The 1st two images from NASA Juno’s June 7, 2021, flyby of Ganymede (Jupiter’s giant moon) have been received on Earth. The photos are one from the Jupiter orbiter’s JunoCam imager and the other from its Stellar Reference Unit star camera. In remarkable details, the surface is shown, including bright terrain, clearly distinct dark craters, and extended structural features possibly linked to tectonic faults.
According to Juno Principal Investigator Scott Bolton of the Southwest Research Institute in San Antonio, “This is the closest any spacecraft has come to this mammoth moon in a generation. We are going to take our time before we draw any scientific conclusions, but until then we can simply marvel at this celestial wonder.”
The spacecraft’s JunoCam visible-light imager using its green filter captured almost an entire side of the water-ice-encrusted moon. Later when the identical image versions come down, incorporating the camera’s blue and red filters. Experts of imaging will be able to provide a color portrait of Ganymede. Image resolution is about 0.6 miles per pixel.
Juno’s Stellar Reference Unit, a navigation camera used to keep the spacecraft on course, provided black and white images of Ganymede’s dark side bathed in dim light scattered off Jupiter. Image resolution is between 0.37 to 0.56 miles per pixel.
According to Heidi Becker, Juno’s radiation monitoring lead at JPL, the condition in which they collected the dark side image of Ganymede was best for a low-light camera like their Stellar Reference Unit. What is seen by JunoCam in direct sunlight this is a different part of the surface. It will be exciting to see what two teams can piece together.
In the coming days, from its Ganymede flyby, the spacecraft will send more images. With the Jovian moon, the solar-powered spacecraft’s encounter is expected to give more insight into its magnetosphere, ionosphere, composition, and ice shell. It will also prove measurements of the radiation environment that will help in future missions to the Jovian system.