If alien life is possible in the ocean under the icy surface of Europe, it could get its start from comet icy fragments that delivered vital ingredients, the researchers said.
Imagine a geyser hundreds of kilometers high. Sounds amazing? And on satellite Jupiter they exist, and studying these super geysers could give us an invaluable insight into this unique ice-covered planet.
New calculations show that a particular family of comets has mass, speed and the ability to do this - to penetrate the full spectrum of ice thickness Europe.
“This is one of the best candidates for the ecosystem,” said Ronada Cox of Wilhelm College, Massachusetts, regarding the ocean of Europe. “But how did the biological elements get into the ocean?”.
To find out if the icy chemical rich comets could do this, she and her team simulated the impact on the entire spectrum of comets that were influenced by Jupiter, and fell into relatively short orbits around the Sun - the so-called comets of the Jupiter family. The team simulated the collisions of these famous comets in the ice thickness range. Their results were unexpected and led to a new understanding of the actual thickness of the ice crust of the satellite.
“It turns out that it doesn't matter how thick the crust is,” said Cox, lead author of the article in the latest issue of Geophysical Research-Planets. “It's all about the frequency of strikes over a very long period of time - in this case almost five billion years.” “If the ice of Europe, for example, lies at a depth of 40 kilometers (25 miles), a comet will be required from 5 to 7 km (3-5 miles) in diameter in order to break through it,” she said.
They found out that the chance that this would happen to the comet of the Jupiter family is once every 100 million years. This means that the chance that this has already happened in the last five billion years is very high.
Chances of passing through the ice will be much higher if the ice is thinner. “Thin ice will allow smaller, numerous comets to break through ice every 10 million years,” Cox explained.
“This means that the crust has often made its way through geological time,” said Cox.
It also means that two dozen craters in Europe today can be compared with impact craters.
“We will get the best result if the ice thickness is from 10 to 15 km (6 to 9 miles),” Cox said. “This ice thickness is consistent with other studies that estimate Europe’s ice thickness using completely different methods,” she added.
“I think this is the most successful and meticulous work in terms of the ratio between the thickness of the ice shell of Europe and the size of the craters depth on the surface,” said Jay Melosh, an expert on planetary influences. “I am particularly impressed that the authors were able to find the corresponding crater depth and diameter in the entire crater size range in Europe and get an excellent result of 10 km (6,2 miles) - the thickness of the ice shell. There has been a long-standing controversy over what kind of ice on Europe is thin (that is, from 7 to 15 km) or thick (about 40 km) ”. “If the blows go through the ice, then there must be a trace,” Cox said. “We do not know what kind of geomorphism there is. What should they look like now when they are frozen? ”.
“They can look like a spotty, complex polar landscape of Europe called“ Chaotic Terrain ”. Very similar models looking at the surface were created by re-freezing ice after exposure to sea-ice explosives on Earth, ”said Cox. "But as the only possible option on Europe, she sees a collision with comets."
If so, and the ice has a fine line, this is good news for life on Europe, and we have a chance to find it.
“The Cox and Bauer document strongly supports the thin shell theory,” said Melosh. “This is good news for the astrobiology community because it means that the exchange of materials between the surface and the bottom of the ocean is relatively easy, so nutrients for the prospective European biosphere can be obtained and samples of this biosphere can be extracted to the surface.”