Along with Mars, Jupiter’s satellite Europa has long been concerned with the imagination of science fiction writers as a place that can Harbor life in the Solar system besides Earth. Scientific fact was the detection of subsurface oceans of water under a thick icy crust. And where there is warm liquid water and suitable chemical composition, there can be no life.
However find out it will certainly be difficult. One of the most complicated and expensive solutions is to land on the satellite and to drill a hole in the ice to collect water samples beneath. But there is another option. The work, published in Nature Astronomy showed that over the surface of Europa’s ocean may appear plumes, and thus the spacecraft could simply fly through them and take the water. These findings are extremely important for future missions Europa Clipper and JUICE.
The presence of geysers on the icy moon assumes not for the first time. The Hubble space telescope has seen signs of transient plumes over the oceans of Europe in 2012 and 2016. But his findings were controversial — the data, in the end, was going from afar (because the Hubble was in orbit around the Earth). The new data came from this flyby of Europe during the Galileo mission in 1997, and greatly strengthened the evidence of plumes on the moon.
We don’t know exactly how thick ice crust on Europa and how deep its subsurface ocean. A study in 2011 showed that there may be places where water will be relatively close to the surface, gathering in large lakes with crushed ice, like the Antarctic structures on Earth.
The Lessons Of Enceladus
The Cassini mission to Saturn have found huge plumes of water over the small moon Enceladus. The first hints came from the deviations of the magnetic field and abundance of charged particles in a certain region of the moon. We know that the dense gas arising of molecules and atoms in the water loop becomes charged (ionized) when the electrons are knocked out. This makes it conductive and causes changes in the surrounding magnetic fields.
Then plumes actually was captured on several pictures, they looked like tiger stripes near the South pole. Gravity measurements in this area allow us to think that they are the source of the subsurface ocean.
Cassini flew past Enceladus twenty-two times, and it is possible to investigate the plumes, erupting directly from the ocean below. In addition to the usual water, ions and charged particles in the plumes, Cassini found sodium the characteristic salinity of the ocean. Also found silicates that tells about the sandy bottom of the ocean and possible to exist hydrothermal vents.
This is important because the chemical reaction between sand and water can provide enough energy in the water to feed the microbial life (as it was at hydrothermal vents on Earth). Finally, in 2017, Cassini also found hydrogen in the plumes, which should be a breakdown product of reaction of sand and water. This suggests that the satellite can support life.
Following these exciting discoveries turned the hunt for plumes on Europa. Based on measurements of Hubble, estimates in 2012 showed that the amount of water emitted by the plumes of Europe, can be 30 times greater than that of Enceladus. Some geysers in height was more than 200 kilometers. Like Enceladus, the bottom of Europa’s ocean most likely consists of sand and stone, in contrast to the oceans of other satellites such as Ganymede and Callisto, whose icy bottom of the ocean.
In the new study magnetometer data from the Galileo flyby, 400 kilometers above the surface of Europe was revised and compared with modern computer model of how to behave like a charged gas to Europe. The results showed that there is a dense region of charged particles. This is most likely plume.
The upcoming mission
As in the case of Enceladus, plumes of Europe offer the exciting perspective to directly examine the material subsurface ocean. It will take two future missions. JUICE, a mission of the European space Agency, will begin in 2022 and arrive at Jupiter in 2030. In the framework of the flyby scheduled two approaches to Europe, and then orbit Ganymede in 2032.
Europa Clipper, a mission NASA will execute 45 flybys of Europa. Both of these missions will be able to investigate plumes as well as Cassini explored Enceladus. Then offer to send gear or penetrating warheads in Europe, but proposals have not yet found financial backing. Meanwhile, the analysis of samples of loops can tell a lot about what is happening in the ocean. If we’re lucky, we may even be able to detect signatures of biological activity. Unfortunately, the “Cassini” was not equipped to search for these signatures at Enceladus.
What is the conclusion? Now in our Solar system there are four possible locations for the existence of life beyond Earth. First, the Mars, which had good conditions for life 3.8 billion years ago. We will explore it by means of the ExoMars Rover 2020. He will be able to drill up to two meters of the surface in search of biomarkers. Also in 2020 to Mars will be sent a new NASA Rover with the recently announced helicopter.
But on Europa and Enceladus might also be life, and sample loops will help determine whether this is so. On the moon of Saturn Titan, we also found signs of a complex prebiotic chemistry that once brought forth life on Earth. This means that Titanium may be a suitable place for the future or perhaps current life.
In addition to planning missions to Mars and Europe is also important to return to the Saturn system and look for life somewhere else. Who knows, maybe in a few years we will find signs of alien life, any alien germs.