NASA Juno spacecraft picks up hints of activity on Jupiter's icy moon Europa.

[LazyHippo]

(Image credit: NASA/JPL-Caltech/SETI Institute)
 

NASA's Juno spacecraft made a close flyby of Jupiter's intriguing moon Europa in 2022, revealing potential hints of present day surface activity.

 

The spacecraft's Stellar Reference Unit (SRU), which is a star camera designed to assist Juno's onboard attitude determination, was used to image Europa's surface with high resolution while being lit up by Jupiter-shine, or sunlight scattered off Jupiter.
 

The SRU image from the flyby is explored in an article published in the journal JGR Planets on Dec. 22, 2023. The image shows an oddly-shaped area of the icy surface, measuring 23 miles by 42 miles (37 kilometers by 67 kilometers) and resembling a platypus. In other words, it exhibits a "body" part in the north and a "bill" part in the south. Both areas — which are joined by a cracked neck-like formation — contain large ice blocks that are each about 0.62 miles (1 km) in size and cast shadows.
 

Comparisons with images of similar resolution from NASA's earlier Galileo spacecraft, which studied Jupiter from 1995 until 2003, suggest changes in the southern part of the "platypus" area. These hint that changes might have taken place on Europa's surface since the Galileo images were taken.

 

However, the team of authors, led by Heidi N. Becker of NASA's Jet Propulsion Laboratory (JPL), state that the evidence isn't conclusive due to differences in imaging quality and conditions.
 

The 2022 image also includes nearby low-albedo deposits which may be associated with subsurface liquid water, the researchers say. These dark stains may be associated with plumes thought to be spewing out water.

While not conclusive, however, the Platypus makes a compelling target for future missions such as NASA’s Europa Clipper and Europe's JUICE to investigate and possibly confirm present day surface activity on Europa.

 

JUICE launched in April of 2023 and will arrive at Jupiter in December 2031. Europa Clipper is set to launch on Oct. 6 this year on a Falcon Heavy rocket.
 

Figure 1:

 

 

Europa is considered a prime target for investigating ocean world habitability (National Academies of Sciences, Engineering, and Medicine, 2022; National Research Council, 2011), and updated maps of the surface are especially relevant to the future exploration of Europa, as the imaging coverage from prior missions is very limited. Juno's 29 September 2022 E45 Europa flyby provided a unique opportunity (and the last prior to the arrival of Europa Clipper and JUICE) to examine this icy body at close range with a suite of remote sensing instruments. Here, we report geologic mapping updates and sites of potential recent surface activity based on high-resolution low-light visible imaging by the Juno Stellar Reference Unit (SRU).
 

Images of Europa were previously acquired by the Voyager, Galileo and New Horizons spacecrafts (Schenk, 2010) and are highly variable in their effective resolution and data quality. New Horizons images are at ∼15–30 km ground pixel scales and hence are primarily useful for change detection (Schenk, 2020), photometric, and other non-geologic studies. Most Voyager coverage is at comparable pixel scales, except for two ∼2 km scale multi-frame mosaics near 180°E longitude that are far from the SRU's target area on the sub-Jovian half of the leading hemisphere. The majority of Galileo images with a resolution better than 1 km are of the anti-Jovian hemisphere (see Figure 1), but Galileo did acquire a near complete mosaic of the SRU's target hemisphere at ∼1 km pixel scale. As most of the mosaic was acquired under high solar illumination, shading variations due to topography are nearly nonexistent, making the Galileo images difficult to interpret for morphology and relief (the images were also significantly affected by radiation noise during CCD readout). Nevertheless, the Galileo images provide useful context for our analysis of the Juno SRU image of Europa's surface.

Edited January 28 by LazyHippo