Enceladus, Europa and the TRAPPIST-1 Systems as Potential Sources of Life

Tuesday 4th December, 2018

Our speaker was Dr Martin Braddock who currently works in the pharmaceutical industry researching new drugs for asthma and COPD. However, he has had a lifelong passion astronomy and is especially interested in astrobiology, so he was more than pleased to come and talk to us about "Enceladus, Europa and the TRAPPIST-1 System as Potential Sources of Life".

He began by giving a quote from Arthur C Clarke: "Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying." He then continued by saying that Enceladus, the sixth largest moon of Saturn, is one of the places in the Solar System that may harbour extra-terrestrial life. Scientists involved with NASA's Cassini spacecraft came to this conclusion when it flew past the moon and observed jets of icy particles coming from huge cracks along the moon's south polar region.

Dr Braddock then continued by saying that these geysers eject material at speeds of about 800 miles per hour and the plumes travel hundreds of miles into space. Some of the erupted material even escapes the moon's gravity and forms the E-ring around Saturn. The violent eruptions are thought to be due to a process known as tidal heating whereby Saturn's gravitational pull stretches and squeezes the moon. This energy source could be used by lifeforms that may be living in the saltwater ocean underneath the moon's icy crust.

He then told us that there is another icy moon with a subsurface ocean that scientists would like to study — Jupiter's smallest moon, Europa. This moon is also flexed by the gravitational pull on it by its central planet, keeping its internal ocean relatively warm and liquid. The Hubble Telescope has also confirmed that Europa also has water jets erupting from its surface. Europa's icy surface is even more irregularly cracked than that of Enceladus and scientists have given it the name "chaos terrain" to emphasize the jumble of ridges, cracks and plains that cover the moon.

Dr Braddock mentioned that scientists think that if life is found in these subsurface oceans it will probably be a type of life known as extremophiles. These are organisms that can live in areas of either extreme heat or cold, high pressure or acidity, and even areas subject to high doses of radiation. In the case of Europa or Enceladus, it is thought that life is most likely to exist at the bottom of their salty oceans and would be in the form of simple microorganisms such as bacteria.

He concluded the talk by saying that scientists now have the ability to study planets outside our Solar System for signs of habitability. In May 2016 a robotic telescope called TRAPPIST spotted a number of planets crossing their parent star by noticing the star's light dimming very slightly as they crossed its disc. This solar system, designated TRAPPIST-1, is located in the constellation of Aquarius and has a cool red star at its centre that is only slightly larger than Jupiter but with more mass. Five of the seven orbiting planets are similar in size to Earth and three of these are found within a region known as the habitable zone where water can exist as liquid making the possibility of life more likely.