In the late 1970s, NASA's two Voyager spacecraft went past Jupiter's moon Europa and discovered convincing evidence that the moon's ice crust conceals a global liquid water ocean.
Europa's liquid water ocean spinning against a rocky interior makes it a potential target for the hunt for alien life, but its ice crust, which may be up to 30 kilometers thick, has kept the ocean out of reach of future space missions.
However, new research published Tuesday in the journal Nature Communications shows that planetary scientists might discover another way to sample Europa's deep seas. Scientists have discovered a type of ice ridge in the Earth's Greenland ice sheet that resembles the numerous ridges that stretch around Europa's surface, and if the structures share a mechanism, it could mean that water from the moon's depths can be found — and possibly accessed — at shallow depths within Europa's ice.
Riley Culberg is a geophysicist at Stanford University in California, although he collaborates with an interdisciplinary team of researchers who often share their findings. Nonetheless, he was caught aback when one of his colleagues showed the team photos of ridges crisscrossing Europa's surface.
“It’s like, ‘Wow, this looks exactly like this super weird thing that I saw in my data from Greenland the other day,’” Dr Culberg said.
What he saw in Greenland was a "double ridge," a roughly kilometer-long line of parallel ice ridges approximately two metres in height, divided by a 50-meter-wide dip.
“If you sliced it in half and looked at the cross-section, it would be kind of like the capital letter ‘M’,” Dr Culberg said.
While the Greenland double ridge is the only one discovered so far, Europa includes other such double ridges, but on a greater scale.
“On Europa, these might be 160 to 200 metres tall,” Dr Culberg said.
Dr Culberg said that the double ridge in Greenland looked to be the consequence of water melting on the surface and then seeping into the ice, where it refreezed.
“Because water expands when it freezes, that interior water in the core of this pocket gets pressurised,” he said. “We think eventually there was so much pressure there that it fractured, and that you have these little sort of up-shoots of water getting forced out of the water pocket and then sort of forced the surface to also dome up into these ridges.”
On Europa, a similar process could be at work, except that the surface is much too cold to melt ice. If there is water in Europa's ice shell at a shallow enough depth to refreeze and form the twin ridges, it must have originated from below.
“This is maybe water from the subsurface ocean that can get forced up through fractures inside of the ice shell,” Dr Culberg said. “Or possibly you could get some kind of internal melting inside of the shell if you have a like plume of warm, buoyant ice that rises far enough up in it.”
Regardless of how it gets there, the paper suggests that material from far deeper inside Europa's ice, or underneath, might be discovered at depths as shallow as a few kilometres, boosting the possibility that future space missions could reach and examine the material for evidence of life. While drilling through 30 kilometres of thick ice is a significant undertaking, drilling through a few kilometres is a common occurrence on Earth.
“We absolutely do drill deep ice cores through three and a half kilometres of ice in central Greenland or central East Antarctica,” Dr Culberg said. “It takes a pretty big setup, it takes a lot of power — you’re not going to pop this on like a Mars-sized rover or something — and it’s going to be difficult, but this is something we do on Earth.”
NASA's Europa Clipper mission is already under development and scheduled for launch in 2024. So its is possible that by 2026 or 2027 we may have discovered alien life in our solar system or at atleast for now it seems promising.
Reference(s): Peer-Reviewed Research Paper,
Comments
Post a Comment
Share your thoughts