Juno captures the highest-resolution image of Jupiter's moon Europa ever

Surface features of Jupiter’s icy moon Europa are revealed in an image obtained by Juno’s Stellar Reference Unit (SRU) during the spacecraft’s Sept. 29, 2022, flyby. Credit: NASA/JPL-Caltech/SwRI

Observations during the spacecraft's moon flyby offered the first close-up of this ocean planet in over two decades, resulting in amazing photos and novel science. The highest-resolution image of Jupiter's moon was ever captured by NASA's Juno spacecraft. Europa provides a close-up look at a perplexing section of the moon's highly broken ice surface.

The view spans around 93 miles (150 kilometers) by 125 miles (200 kilometers) of Europa's surface, displaying an area crisscrossed by a network of tiny grooves and double ridges (pairs of long parallel lines indicating elevated features in the ice). Dark stains towards the upper right of the photograph, as well as just to the right and below center, might be caused by something from below erupting onto the surface. A surface feature that resembles a musical quarter note measures 42 miles (67 kilometers) north-south by 23 miles (37 kilometers) east-west. The white spots in the photograph represent the marks of penetrating high-energy particles from the moon's harsh radiation environment.

The black-and-white image was captured by Juno's Stellar Reference Unit (SRU), a star camera used to orient the spacecraft, during the spacecraft's flyby of Europa on September 29, 2022, at a distance of around 256 miles (412 kilometers). The image, with a resolution ranging from 840 to 1,115 feet (256 to 340 meters) per pixel, was acquired as Juno sped by at roughly 15 miles per second (24 kilometers per second) over a nighttime area of Jupiter's surface, faintly illuminated by "Jupiter shine" sunlight bouncing off Jupiter's cloud tops.

The SRU, which was designed for low-light circumstances, has also proven to be a powerful research instrument, identifying shallow lightning in Jupiter's atmosphere, photographing Jupiter's mysterious ring system, and now revealing some of Europa's most interesting geologic structures.

According to Heidi Becker, the SRU's principal co-investigator, this image reveals an extraordinary degree of detail in a location that has never been captured at such resolution and under such revealing lighting circumstances. Juno's pioneering capabilities are demonstrated by the team's employment of a star-tracker camera for science. These characteristics are quite appealing. Understanding how they developed and how they relate to the history of Europa teaches us about the internal and external processes that shape the ice crust.

In the next weeks, Juno's SRU scientists will not be the only ones busy examining data. During Juno's 45th orbit around Jupiter, all of the spacecraft's research sensors were gathering data both during the Europa flyby and again a few hours later when Juno went over Jupiter's poles.

According to Juno Principal Investigator Scott Bolton of the Southwest Research Institute in San Antonio, Juno began with a singular emphasis on Jupiter. The crew is overjoyed that during our extended mission, we were able to broaden our analysis to encompass three of the four Galilean satellites as well as Jupiter's rings. Juno has now seen close-ups of two of Jupiter's most fascinating moons, and their ice shell crusts appear significantly different from one another. Io, the most volcanic body in the solar system, will join the group in 2023. In June 2021, Juno was accompanied by Jupiter's moon Ganymede, the solar system's biggest moon.

Europa is the solar system's sixth-largest moon, with an equatorial diameter of almost 90% that of Earth's moon. Scientists are sure that a salty ocean exists behind a miles-thick ice crust, raising concerns about the water's potential habitability. The Europa Clipper mission, which will arrive in the early 2030s, will attempt to address these issues concerning Europa's habitability. The Juno flyby data gives a peek of what the mission will disclose.