The first image the spacecraft took of the Juno mission by NASA passing by Europa, an ice-covered moon of Jupiter, has already reached Earth. The photograph, which shows surface features of a region near the equator called Annwn Regio, was captured during the spacecraft’s closest approach on Thursday, September 29, at a distance of approximately 352 kilometers.
This is the third approach in history below 500 kilometers of altitude and the largest of a spacecraft to Europe since January 2000, when the spacecraft Galileo NASA came within 351 kilometers of the surface.
Europa is the sixth largest moon in the solar system, slightly smaller than Earth’s moon. Scientists believe there is a salty ocean beneath a crust of ice several kilometers thick, raising questions about possible conditions capable of supporting life.
Juno’s close-ups and data from its Microwave Radiometer (MWR) instrument will provide new details about how Europa’s ice structure varies under its crust. This information can be used to better understand this satellite, including data in the search for regions where liquid water may exist in shallow subsurface pockets.
The segment of the first image of Europa taken during this flyby by the camera (public access) JunoCam The spacecraft is centered on a strip of Europa’s surface north of the equator.
Good contrast in the area between day and night
Due to the greater contrast between light and shadow observed along the so-called terminator (moving line separating the day side from the night side), terrain features can be easily seen, including tall blocks that cast shadows, while ridges bright and dark curve across the surface. A pit near the terminator could be a degraded impact crater.
While Juno’s data will be exciting, the spacecraft only had a two-hour window to collect it, hurtling past the moon at about 14 miles per second.
“It’s very early, but everything indicates that this flyby was a great success,” says Scott Bolton, Juno principal investigator at the Southwest Research Institute in San Antonio (USA), “this first image is just a glimpse of the new and extraordinary science to be gained from the full suite of Juno instruments and sensors that acquired data as we skimmed across the moon’s icy crust.”
During the flyby, the mission collected what will be some of the highest resolution images of the moon (1 kilometer per pixel) and obtained valuable data on the structure of its ice cap, its interior, the composition of its surface and its ionosphere. , in addition to the moon’s interaction with Jupiter’s magnetosphere.
“The science team will compare the full set of Juno images with images from previous missions to see if Europa’s surface features have changed over the past two decades,” says Candy Hansen, who heads camera planning at the Tucson Institute for Planetary Sciences in Arizona (USA), and adds: “JunoCam images will complete the current geological map, replacing the existing low-resolution coverage of the area.”
Future Europa Clipper mission
With all the new data on Europa’s geology, Juno’s observations will benefit future missions to the Jovian moon, including the mission Europa Clipper from NASA. Europa Clipper, scheduled for launch in 2024, will study the moon’s atmosphere, surface and interior, and its main scientific goal will be to determine if there are places below Europa’s surface that could support life.
Building on observations from Juno and previous missions such as Voyager 2 and Galileo, the Europa Clipper mission, which is scheduled to arrive at Europa in 2030, will investigate the moon’s habitability and help to better understand its global subsurface ocean, the thickness of its ice crust and look for possible plumes that may be ejecting subsurface water into space.
This week’s close flyby altered Juno’s trajectory, reducing the time it takes to orbit Jupiter from 43 days to 38 days. It also marks the second encounter with a Galilean moon during the probe’s extended mission. The mission explored Ganymede in June 2021 and is scheduled to make close flybys of Io, the most volcanic body in the solar system, in 2023 and 2024.