In 1970s, two voyager spacecraft of Nasa flew by Europa (Jupiter’s moon) and observed a solid proof that liquid water ocean of the globe hide under the moon’s icy shell.
The ocean of liquid water that whirls alongside the rocks and makes Europa a major target for the exploration of extraterrestrial life, but its icy crust surface which is probably as thick as 30 kilometers and making ocean out of the reach from future space missions.
A recent published study in the journal Nature Communication1 proposes that planet scientist must find the other possible ways to sample the deep waters of Europa. It has been observed that Greenland ice sheets on Earth are very similar appearance to the ridges of Europa surface. If the structural mechanism of the surface originated then the water from the moon’s depths can also be found and accessed at shallow depths within Europa’s ice.
Riley Culberg is a geophysicist who is studying glaciers and ice sheets at Stanford University in California. When his friend showed him image of Europe surface ridges, he was just surprised and reacted as:
“It’s like, ‘Wow, this looks exactly like this super weird thing that I saw in my data from Greenland the other day,’”
According to Dr. Culberg in Greenland, there were almost 1 kilometer long and 2 meters tall parallel ridges of ice which were separated by a 50 meters wider trough. He also mentioned that if you slice these ridges from half and look at the cross section it appears similar to capital letter “M”.
“Europa has many such type of double ridges whose height vary from 160 – 200 meters but Greenland has only 1 double ridge so far,” Dr Culberg said.
Dr. Culbeg also described the method of double ridge formation in Greenland he said, double ridge formed due to melting of water on the surface and after water infiltration down to the ice causes refreeze.
“At freezing water expands, water in the interior core of pocket get pressed,” he said. “Ultimately lots of pressure built inside the core and water getting enforced to jump out of the water pocket which force the surface and appear into ridges”.
Similar mechanism could be happen on Europa. If the water in Europa’s ice shells is present in shallow enough depth to form a double ridge then it should be originate from below.
He said, “Formation of these ridges may has two phenomena, one is that water in the subsurface forced up from the fractured ice shell or may be due to any kind of internal melting takes place inside the shell”.
The paper suggests that material of Europa’s ice and its depth as shallow as few kilometers could be assessed deeply in future space missions and also evaluated that either it has any sign of life or not. Drilling of such hard ice up to 30 kilometers is a difficult task however drilling through few kilometers on Earth is happen on regular basis. He said, “In central Greenland we can drill ice cores up to three and half kilometers but it takes pretty big effort and huge setup and you are not gonna to do this on Mars like big planet, but this task could be done on Earth”.
1 Culberg, R., Schroeder, D. M. & Steinbrügge, G. Double ridge formation over shallow water sills on Jupiter’s moon Europa. Nature Communications 13, 2007, doi:10.1038/s41467-022-29458-3 (2022).