Enceladus, Titan and the Search for Life
I actually hoped to write about the search for life in a later blog post but the powers that be at NASA have been in the media recently speculating the chances of life on Enceladus, the sixth largest moon of Saturn. Enceladus is a frozen world orbiting Saturn with a surface of fresh clean ice. Plumes of what appears to be water ice have been observed shooting high above Enceladus from a sub surface ocean beneath the smooth icy surface. Of course this has caused a media stir and plans of a mission to Enceladus to investigate are in motion.
Enceladus as viewed from Cassini Orbiter. Credit NASA
When we ask if we are alone people can often think of advanced civilisations similar to mankind or if you are a fan of science fiction, strange aliens armed with probes! Studying the rich biology, geology and physics of our solar system, it is certain that our other planets and moons do not have advanced civilisations on them. Voyager 2 flew by the outer solar system and reached the icy worlds of Uranus in 1986 and Neptune in August 1989. Apart from a few extra moons we couldn’t see from ground based telescopes, there was no evidence of inhabitants or space ships or really anything of note. Apart from the magnetic fields of the planets and their surface/atmospheric compositions.
The most exciting discovery of the Voyager 2 mission to the outer solar system was, in my opinion, Saturn’s moon Titan! The largest moon of Saturn and the second largest in our solar system behind Jupiter’s moon Ganymede. Titan was observed as having a 600km thick atmosphere but due to the flyby, did not survey much of the surface. The Cassini Orbiter mission to Saturn throughout the 2000s was able to carry out more detailed analysis of Titan’s surface and the findings were staggering. Titan contains massive lakes! You heard me, lakes! Although not water lakes, they are massive lakes of liquid methane and Titan certainly has Earth like weather cycles that substitute Earth’s water for liquid methane. It rains methane on Titan and its surface is geologically active, most likely in the form of volcanoes that can spew out the liquid methane and other substances and from the almighty pull that Saturn has on the planet. Cassini is still in action and has flown by Titan almost 100 times in the past 10/12 years. NASA landed on Titan back in 2007 when the Huygens probe detached from Cassini and parachuted down to its surface. It was able to measure the surface pressure, gravity and temperature. I love the idea that Titan may also have rainbows.
Titan with altered image to demonstrate cloud activity above liquid Methane Lakes. Credit Cassini Orbiter – NASA.
So in our solar system, Titan is an Earth like world, complete with atmosphere, active weather cycles and geology. Unfortunately, there aren’t any cities or towns on Titan and the existence of a form of mankind is nil. The chances of microbial and microscopic life are reasonably large. Titan is a billion miles from the Earth give or take and doesn’t receive a lot of sunlight. I would like to rewind back to 4.54 billion years when our sun was much smaller and didn’t have the same energy output as it does now due to its growth through the aeons. Titan is very similar to what Earth was like in the earliest of times as life was beginning to flourish on our planet. Enceladus on the other hand is a rocky and icy world where the ocean underneath its surface would receive only the most minimal of sunlight, another catalyst for life. It’s difficult to tell if abiogenesis can occur in such conditions. Abiogenesis is the origin of living matter from non-living matter, more specifically hydrocarbons.
So we have an example of a primordial like world extremely similar to our infant Earth, and NASA wants to go to Enceladus!? I certainly find this odd and many astrophysics and astrobiology circles find this strange also. In fact, if your humble scribe can offer an opinion, Titan could be reclassified as a Planet in a binary system with Saturn. After all, it’s certainly more of a planet than what Mercury is. Mercury can almost be reclassified as being a solar satellite as opposed to a planet. Enceladus on the other hand is certainly a moon. If we are going to find life, all roads lead to Titan. It’s a shame that it’s Saturn’s winter and there isn’t an awful lot of light on Titan right now but it’s the perfect place to look. It may take 20 years plus to do a full chemical survey of Titan but it would certainly be worth the wait. What are your thoughts?
Feature image by: https://www.coursera.org/learn/astrobiology