Enceladus mission: Search for Life
"Does life really exist beyond Earth?"
Illustration of the interior of Saturn's moon Enceladus showing a global liquid water ocean between its rocky core and icy crust. The thickness of the layers shown here is not to scale. Credit: ESA
Search for life on other planets has always been one of the most intriguing yet important parts of space exploration. But this time it is not on a planet but on a moon. Saturn's moon Enceladus has been hiding a queer world of water under its cover which possesses the possibility of having a life. Of course, the nature of the species is itself mystical. It may be microorganisms, aliens, or some strange kind of species that may or may not be harmful to us.
A string of probes has been sent to Enceladus: Voyager 1, Voyager 2, and Cassini. But the most prominent discoveries were made during the Cassini Mission. Let's have a look at how it all came to the fore.
Cassini and its findings
A close observation of Enceladus by Voyager 1 and Voyager 2 revealed the diverse and more surprisingly youthful terrains of Enceladus. But it wasn't until the Cassini mission that the mysteries of Enceladus were unveiled. Close flybys by Cassini revealed the intricacies of the surface and environment of Enceladus.
In February 2005, Cassini made its first close flyby of Enceladus. With the help of its magnetometer (an instrument used to measure the strength and sometimes the direction of the magnetic field), it was discovered that the magnetic field of Saturn wiggled at a point, which was due to the interaction between Saturn and Enceladus. Enceladus is immersed in Saturn's magnetic field and is geologically active. It was found on further research that a plume of water vapor(or geysers) was coming off from the South Pole of Enceladus, which was almost like that of comets, and was seen as a whitish glow near the moon. These water vapors become ionized and fill the environment around Saturn. Now, I guess, you have come to know what caused the disturbance in Saturn's magnetic field.
On a closer flyby, Cassini's images showed something spectacular. There were cracks or stripes(narrow jets) at the South Pole of the icy body and heat was leaking from the stripes. Besides, organic material, dust, and simple hydrocarbons were found venting from the South polar region in subsequent flybys. This was the biggest discovery of the Cassini mission. Liquid water was found so far away from the Sun! Something that boggled the minds of scientists. The geysers were so large that they covered 150 miles in space. But the question here is: what produced these plumes that were so extreme?
Such strong plumes can only be produced when Enceladus has a great amount of water and heat underneath its icy crust. The water erupts from the surface due to the gravitational force of Saturn (just like tides on the earth are caused by the gravitational forces of the sun and the moon). It is believed that the ocean is being heated by the moon's core.
Possibility of life
Illustration of the interior of Saturn's moon Enceladus showing a global liquid water ocean between its rocky core and icy crust. The thickness of the layers shown here is not to scale. Credit: NASA
Now you may be contemplating, "why does this discovery matter so much?" The reason is: "liquid water" and "heat" are key ingredients in the search for life. This means that may be taking place in hydrothermal activity in the ocean of Enceladus may develop the conditions that give rise to life. Since Enceladus has an active core deep beneath the sea, the environment may be similar to that at the bottom of the Earth's ocean. Hark! Could this water environment harbor alien life?
In its closest flyby, Cassini dives through the plumes of the Enceladus. Going deeper into the plumes, Cassini found salt in its composition. Another Essential Component In Search For Life!
When salty water comes in contact with a rocky surface, some special chemistry begins to take place. Heat acts as a catalyst in the process. You might have noticed that now we have everything required for the development of life- water, salt, heat, organic materials, and nitrogen-bearing compounds. So, there you go! It is now possible that we may have alien life on this moon. But it is still unknown what sort of life will be found there.
Future prospects of the mission
Cassini was not equipped enough to search for the habitability of the ocean on Enceladus. However, after Cassini's remarkable findings on Enceladus, NASA is all set to send another mission to the moon in search of potential life on it.
NASA's Orbilander is a proposed flagship mission to Enceladus. Since a single spacecraft first orbits and then lands on Enceladus, it is named Orbilander. It will collect samples from four different reservoirs created by plumes.
The Orbilander will conduct orbital science for 1.5 years and then will land on the surface of Enceladus. While orbiting, it will collect samples from plumes in its close flyby of Enceladus. Upon landing, Life Detection Suite(LDS), a set of five instruments conducting complementary and orthogonal bio signature-seeking measurements, will be operational for two years. Then, LDS measurements of the collected samples will be conducted to determine if Enceladus' water has suitable chemicals for life. Geophysical and geochemical investigations, in orbit and on the surface, will reveal the physio-chemical state of the ocean and core.
Orbilander will also search for lipids, amino acids, and cells in the plume material. It is equipped with a mass spectrometer to determine the mass of molecules, a seismometer, and a DNA sequencer. Orbilander is expected to launch by 2038.
It will be exciting to see if we share this universe with some other biosphere as well. For now, we can only speculate on the appearance and nature of the alien life on Enceladus.
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