Penitentes – The Giant Ice Blades of Europa and Pluto

The Jagged Ice-Spires of Europa

NASA’s recent research gives strong indication of the existence of Penitentes on both Europa and Pluto.

Europa, one of Jupiter’s moons is a small, icy world harbouring a wide-ranging sub-surface salt-water ocean. Radar signals sent from the Arecibo Observatory (Puerto Rico) to collect data about Europa’s surface features delivered indications of a bumpy topography consisting of yawning ridges and crannies.

NASA’s New Horizons spacecraft to Pluto, which it flew-by in 2015, also crossing paths with Jupiter and Europa en-route, in February 2007, revealing a ‘bladed terrain’ in the icy equatorial regions of Europa. Here the sunlight is at its most intense and the lowest temperatures can drop to -200 degrees C, and it is the ideal environment for the formation of the jagged spikes of Penitentes it is peppered with, to take shape. These towering frozen forest-like regions of razor-toothed ice spires rise to heights of approximately 50 feet (15 m)

Pluto’s Giant Blades of Ice and the Glacial Blades of Earth

NASA New Horizons mission also discovered dramatic Penitentes hundreds of feet tall, consisting almost exclusively of methane ice, on Pluto in the Tartarus Dorsa region, close to the equator.

Comparable, though much smaller bladed edifices of ice and snow – Penitentes, exist along Earth’s equator over the snowy-glacial regions of the Andes at heights of 13,000 ft+ (4,000 m+).

“All these worlds are yours – except Europa. Attempt no landings there.”

– Arthur J Clarke, in his novel “2010: Odyssey Two” (1982)

Europa’s Spiky, Frozen Band of Penitentes

Europa’s Penitentes are much larger than Earth’s because the moon is far colder and drier, its atmosphere is almost non-existent and its gravity a lot lower. Their location around Europa’s equatorial region where the sun is directly above, and they can grow at their greatest speed, creates a spikey frozen band around the middle of Europa ensuring that it would be impossible for any form of lander to alight on the moon.

“The unique conditions of Europa present both exciting exploratory possibilities and potentially treacherous dangerous terrain.
The presence of sharp, blade-like structures towering to almost 50 feet high would make any potential landing mission to Europa extremely precarious.
We hope that studies like ours will help the engineers to develop innovative ways of delivering landers safely on Europa’s surface so that we can find out even more about this fascinating place, and potentially look for signs of extraterrestrial life”

– Cardiff University researcher Dr Daniel Hobley

Because of such dangerous terrain, NASA is instead sending the Europa Clipper mission to Europa by 2025. (Launch date currently planned for October 2024) The orbiter will use a series of flybys while in orbit around Jupiter to study Europa. Whilst its main mission is to establish whether there is anywhere below the icy surface that maybe viable to support life, it is expected that it will also gain new knowledge regarding Europa and its Penitentes.

References/Citations

• Penitentes – The Remarkable Ice Pillars of the Atacama Desert – www.ststworld.com
• 50-Foot-Tall Ice Spikes Cover Europa, New Study Suggests) – https://www.sci.news/space/europa-penitentes-06483.html\
• Study: Daniel E.J. Hobley et al. Formation of metre-scale bladed roughness on Europa’s surface by ablation of ice. Nature Geoscience, published online October 8, 2018, doi: 10.1038/s41561-08-0235-0
• Journal reference: Nature Geoscience, DO1:10.1038/s41561-018-0235-0
• Jupiter’s Moon Europa May Have a Belt Of 15-Metre-Tall Ice Spikes – www.newscientist.com
• Penitente (Snow Formation) – www.en.m.wikipedia.org)
• Author Frank Tavares, NASA’s Ames Research Center
• Solving the mystery of Pluto’s giant blades of ice – www.nasa.gov