On Sept. 29, 2022, NASA’s Juno mission made a close flyby to Europa at a distance of about 256 miles (412 kilometers). During this flyby, the spacecraft Juno’s Stellar Reference Unit (SRU) – a star camera used to orient the spacecraft- captured the highest-resolution photo of Jupiter’s moon Europa. This is the first close-up in over two decades of this ocean world, revealing a detailed view of a puzzling region of the moon’s heavily fractured icy crust.
The image covers about 93 miles (150 kilometers) by 125 miles (200 kilometers) of Europa’s surface, revealing a region crisscrossed with a network of fine grooves and double ridges (pairs of long parallel lines indicating elevated features in the ice). Dark stains just to the right and below the center of the photograph and close to the upper right may result from something from underneath erupting onto the surface.
A surface feature that resembles a musical quarter note, measuring 42 miles (67 kilometers) north-south by 23 miles (37 kilometers) east-west, can be seen below the center and to the right. The white dots in the image result from penetrating high-energy particles that have entered the area due to the intense radiation environment surrounding the moon.
The image, which has a resolution of between 840 and 1,115 feet (256 and 340 meters per pixel), was taken as Juno sped past at about 15 miles per second (24 kilometers per second) over a region of Jupiter’s surface that was at night and dimly lit by “Jupiter shine,” sunlight reflected off Jupiter’s cloud tops.
Heidi Becker, the lead co-investigator for the SRU, said, “This image is unlocking an incredible level of detail in a region not previously imaged at such resolution and under such revealing illumination conditions. The team’s use of a star-tracker camera for science is a great example of Juno’s groundbreaking capabilities. These features are so intriguing. Understanding how they formed – and how they connect to Europa’s history – informs us about internal and external processes shaping the icy crust.”
Juno Principal Investigator Scott Bolton of the Southwest Research Institute in San Antonio said, “Juno started completely focused on Jupiter. The team is excited that we expanded our investigation to include three of the four Galilean satellites and Jupiter’s rings during our extended mission. With this flyby of Europa, Juno has now seen close-ups of two of the most interesting moons of Jupiter, and their ice shell crusts look very different from each other. In 2023, Io, the most volcanic body in the solar system, will join the club.”