The Juno spacecraft approached Europa, and came as close as 219 miles (352 kilometers) away from its surface. Europa is believed to be home to a massive habitable ocean beneath its missive icy crust.
During Juno’s September 29 flyby of Jupiter’s moon Europa, NASA released a close-up image taken by the spacecraft, revealing stunning close-up features of the surface. Juno’s first image of Jupiter’s ice-encrusted moon Europa has been sent back to Earth. On Thursday, Sept. 29, the solar-powered spacecraft captured the image of Annwn Regio, which revealed surface features near the moon’s equator. It was captured at a distance of about 219 miles (352 kilometers).
Only three close passes have been made below 310 miles (500 kilometers) altitude in history, and Galileo came within 218 miles (351 kilometers) of Europa’s surface in 2000. As the sixth largest moon in our solar system, Europa is slightly smaller than our own moon. The presence of a salty ocean beneath Europa’s miles-thick ice shell poses questions about whether life could exist there.
Europa’s surface north of the equator is pictured in this segment of the JunoCam’s first image during this flyby. The terminator (the nightside boundary) contrasts light and shadow, giving a clearer picture of rugged terrain, including ridges and troughs and tall shadow-casting blocks. A degraded impact crater may have formed the oblong pit near the terminator.
As a result of Juno’s observations, future missions to Europa, such as the Europa Clipper, will benefit from this additional information. Europa Clipper will launch in 2024 and study the moon’s atmosphere, surface, and interior with the primary science goal of finding out whether life can exist beneath Europa’s surface. Even though Juno’s data will be exciting, the spacecraft only had a two-hour window to collect it, cruising past the moon at an average speed of about 14.7 miles per second (23.6 kilometers per second).
According to Scott Bolton, Juno’s principal investigator from Southwest Research Institute in San Antonio, the flyby of Europa was a great success. “This first picture is just a glimpse of the remarkable new science to come from Juno’s entire suite of instruments and sensors that acquired data as we skimmed over the moon’s icy crust.”
In the process of the flyby, the mission collected images of the moon with high resolution (0.6 miles or one kilometer per pixel) and gathered valuable information about Europa’s ice shell structure, interior, surface composition, and ionosphere, as well as Jupiter’s magnetosphere interactions with the moon. Candy Hansen, a Juno co-investigator who leads planning for the camera at the Planetary Science Institute in Tucson, Arizona, says that the science team will compare Juno’s full set of images with images from previous missions in order to examine whether Europa’s surface features have changed over time. “The JunoCam images will fill in the current geologic map, replacing existing low-resolution coverage of the area.”
A close-up view of Europa from Juno’s Microwave Radiometer (MWR) instrument will give new insights into the ice’s structure beneath its crust. The information collected from this study can be used by scientists to discover whether there is liquid water in shallow pockets beneath the moon’s surface. NASA’s Europa Clipper mission, slated to arrive at Europa in 2030, will build on Juno’s observations and previous missions such as Voyager 2 and Galileo. With a goal to discover habitability and better understand its global subsurface ocean, ice crust thickness, and possible plumes venting into space, the mission aims to study its atmosphere, surface, and interior.
As a result of the close flyby, Juno’s orbit around Jupiter is now shorter, taking 38 days instead of 43. In addition, Juno’s extended mission marks its second encounter with a Galilean moon. In June 2021, the mission explored Ganymede and, in 2023 and 2024, it will fly close to Io, a moon scientists consider to be the most volcanic body in the solar system.