Juno passes by Europa, revealing the mysterious and icy world [Updated]

Enlarge / The complex, ice-covered surface of Jupiter's moon Jupiter Europa was captured by NASA's Juno spacecraft during flyby on September 29, 2022. NASA/JPL-Caltech/SWRI/MSSS

3:25 PM ET Update: A few hours after Juno's flyby, the spacecraft began sending data back to Earth. NASA has released the first of these processed photos, which shows a region near the moon's equator called Annwn Regio. The data for this photo was collected at a distance of 352 km above the Moon, the closest point of approach during this flyby.

A lot of rugged terrain is visible in this image, including dark ridges and dips across the surface. The oblong pit near the terminator could be a degraded impact crater, according to NASA.

Original post: On Thursday morning, NASA's Juno spacecraft dove within 358 km of the surface of Europa, the large ice-encrusted Moon that orbits Jupiter.

This flyby will give humanity its closest look at Europa since the Galileo mission conducted several close flybys more than two decades ago. However, the Juno spacecraft will carry a suite of more powerful instruments and a much more capable camera than Galileo. So this should be our best look at this intriguing world.

Launched in 2011, Juno reached Jupiter in 2016 to closely study the composition of the largest planet in the solar system, as well as its powerful magnetosphere. After successfully completing its primary mission in 2021, Juno mission operators began using the probe to assess moons in the Jovian system, including Europa, Ganymede, and Io.

Given Juno's existing orbit and Jupiter's massive gravity field, the orbital dynamics of the flyby of Europa are challenging to say the least, and Juno had to make significant changes to its trajectory.

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"The relative speed between the spacecraft and the Moon will be 23.6 kilometers per second, so we're screaming pretty fast," said John Bordi, Juno Deputy Mission Manager at JPL. "All steps must go like clockwork to successfully acquire our planned data, because shortly after the flyby is complete, the spacecraft must be reoriented for our next close approach to Jupiter, which does not occur until seven o'clock. and a half later."

Scientists have long been interested in Europa, which is covered in ice but is thought to have a vast ocean below the surface due to the moon's hot core. There is probably more liquid water in Europe's global ocean than there is on Earth, planetary scientists believe. While the ice sheet is believed to be several kilometers thick, the Hubble Space Telescope has collected data indicating that geysers can periodically eject through cracks in this ice. Given the presence of water and heat, this ocean is considered a potential reservoir for microbial extraterrestrial life.

Juno will bring new tools to study this ice cap. For example, the spacecraft's microwave radiometer will examine Europa's crust, obtaining data on its icy composition and temperature. This is the first time that such data will be collected to study the moon's icy shell.

Visual imagery and science data will help inform NASA scientists as they complete assembly of the Europa Clipper, a large spacecraft set to launch in 2024 on a Falcon Heavy rocket. This mission will be dedicated to the study of the Moon, arriving in 2030 and performing more than 50 short-range flybys to collect data. Eventually, the space agency would like to send a lander but first wants to get data from flyby missions to assess the best location for landing, potentially near a water vapor plume, if they really exist.

Images should start coming back from the Juno flyby of Europe in the next few days. NASA will post them here as they arrive.