Abstract
Areas of Jupiter’s moon, Europa, contain irregular ice floes that are
illustrative of the massive disruption, reorientation, and refreezing
experienced on Europa’s surface as Jupiter’s gravity imparts immense
tidal forces that heat the moon. In recent years, various machine
learning programs have been used to detect surface features on planetary
bodies. Most commonly, such software works to count craters for
estimating planetary surface age or to map sand-filled dune fields whose
shapes may indicate wind or weather patterns. Creating software to
automatically detect Europa’s jigsaw-like ice floes will accelerate
scientific analysis of such terrains once higher resolution images of
the moon arrive in the fall of 2022 from the Juno spacecraft and later
from the forthcoming Europa Clipper mission. In this project, a U-net, a
deep learning semantic segmentation model, was applied to images of the
surface of Jupiter’s moon Europa taken by the Galileo spacecraft to
detect ice floes in the moon’s Chaos Terrains. To measure the quality of
the program developed, the Intersection over Union (IoU), a metric that
measures the goodness of fit for semantic segmentation, was calculated.
Throughout the course of the project, the IoU increased from a value of
0.0012 to 0.286 by adjusting hyperparameters including learning rate and
epochs. Adjusting how the data was labeled also improved performance,
functioning best when ice floes were hand-labeled using loose-fitting
polygons rather than exact edge-mapping. As Galileo faced transmission
issues, the usable dataset was limited to 23 images, 19 of which were
used for training and 4 for testing. In the coming months, higher
quality augmented data should provide additional training images that
should further improve the performance of the U-net. Once the algorithm
is sufficiently capable of identifying floes in the Chaos Terrains, it
may later assist in selection of regions of interest for further study
on Europa or even landing sites for a future proposed lander.