A Closer Look at Titan

In my previous post, I made a mention of Saturn’s moon Titan being a possible host for extraterrestrial life. Turns out that Titan was discovered on this very day, March 25, back in 1655 by the Dutch astronomer Christiaan Huygens. Given this fact, I thought it would be fun to take a closer look at this moon. What’s so special about it? Why do astronomers think it could harbor life?

Source: NASA

A major point of interest is that Titan is the only moon discovered so far that has a substantial atmosphere. It’s atmosphere is about 1.5 times as thick as Earth’s and, like Earth’s, is dominated by nitrogen (McKay, 2005). Along with nitrogen, the atmosphere is rich in organic compounds such as methane and other hydrocarbons (Lemonick, 2010). Obviously, these conditions are very different from what we see here on Earth, but astrobiologists think that  the atmosphere provides precursors for, and can sustain, life. Experiments conducted at the University of Arizona have demonstrated that DNA/RNA bases cytosine, adenine, thymine, guanine, and uracil and amino acids glycine and alanine can be produced from the ingredients in Titan’s atmospheric haze (2010).

Source: Wikipedia

Interestingly, Titan’s surface is devoid of liquid water, which seems to argue against its ability to support life. Yet, others argue that life can exist in the liquid methane lakes that dot Titan’s surface, shown in the image above. These lifeforms would use acetylene, ethane, and other organic solids in combination with hydrogen to derive energy for sustenance (McKay & Smith, 2005). Supporting this idea is the fact that certain lifeforms on Earth, microorganisms called methanogens, exist in a similar manner. The science behind this theory is very dense, so I won’t write it all out here. Instead, I refer you to the  2005 paper written by McKay and Smith which discusses the matter. Furthermore, while the surface does not have water, scientists believe that Titan does have a global subsurface ocean, composed of a water-ammonia mix. As Fortes (2002) writes, conditions within this hypothetical ocean, while extreme by terrestrial standards, are such that life could indeed survive.

In 2005, the Huygens probe landed on Titan’s surface, marking the first landing done in the outer solar system. Atmospheric and surface data obtained by Huygens possibly indicated the presence of methanogen-like life (McKay, 2010). However, abiotic chemical or geological processes cannot be completely discounted. Ultimately, it will take many years of study and exploration to uncover Titan’s secrets. But, if what’s been discovered so far is any indication, the undertaking promises to yield intriguing results. I, for one, am hoping that life is one of them.

To read more:

http://en.wikipedia.org/wiki/Life_on_Titan

http://www.astrobio.net/index.php?option=com_retrospection&task=detail&id=1755

http://www.astronomy.com/en/sitecore/content/Home/News-Observing/News/2010/10/Titans%20haze%20may%20hold%20ingredients%20for%20life.aspx

The article by McKay and Smith: http://www.sciencedirect.com/science/article/pii/S0019103505002009

The article by Fortes: http://www.sciencedirect.com/science/article/pii/S0019103500964005

http://www.spacedaily.com/reports/Have_We_Discovered_Evidence_For_Life_On_Titan_999.html

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3 responses to “A Closer Look at Titan

  • alliemikels

    I thought this was REALLY amazing! Before this post, I had never even heard of the possibility of life on Titan. Which brings me to my question…why do you think that news like this is not widespread? Why doesn’t news this groundbreaking make headlines? I’m sure that if/when life is actually found, people will notice, but it just seems odd to me that the possibility of other life has not caught more attention.

    • Vineet

      I think there are 2 main reasons: 1. Anytime you’re dealing with science, particularly something of this magnitude, you don’t want to jump the gun and make claims that you can’t prove. Back in 1984, a Martian meteorite (ALH84001, see http://en.wikipedia.org/wiki/Allan_Hills_84001#Possible_biogenic_features) was found which, later reported in 1996, apparently provided evidence for ancient life on Mars. This became something a spectacle (even President Clinton weighed in on the matter)… until skeptics began voicing their legitimate concerns with the evidence provided by the artifact. The debate is still going on, but the public made up its mind after doubts emerged, pushing aside a truly astounding discovery all because some within the scientific community did what they were supposed to do: demand more concrete evidence before buying into a claim. Which brings me to point 2: the public tends to not care about “gradual” claims. We want to hear the big stories. We want to hear that we conclusively found life, not that we’re finding clues which help us theorize how life can exist. Collectively, we don’t have the attention span that scientific inquiry requires. And those in charge of informing us, outside of the scientists themselves, know this fact and choose to focus on those stories which are just more attractive. And that’s how stories like these get buried.

  • ikestronomy

    It seems to me that the possibility for extraterrestrial life lies on the moons of our solar system’s outer planets. Between the nitrogen rich atmosphere of Titan and the large ocean under Io’s icy surface, there is so much more for us to learn about these distant objects. When we finally have the technology and funding to send multiple space probes out into these mysterious realms, I believe we will truly realize how much we don’t know and how much we stand to gain from space exploration.

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