Life on Titan could exist even without water

Alan Martin July 7, 2016

Typically, when we ponder alien life we don’t do much outside-of-the-box thinking. There is life on Earth, ergo, if we find a planet that’s similar to Earth in terms of its makeup and proximity to a star, then there’s a good chance of finding life, even if it doesn’t resemble us. How advanced it is will depend on how old the planet is – after all, we are the result of 4.5 billion years’ planetary development. There are a few planets like this, but they’re always too far away to go check in on.

Think outside the box, though, and there are other options. What if a different kind of life can evolve in conditions far removed from our own? If we expand our horizons to consider this, then another option far closer to home comes into focus: Titan.

Titan is Saturn’s largest moon, some 1.4 billion kilometres from us. That’s a long way, but certainly more accessible than Alpha Centauri, say, and it would only take New Horizons around two years to get there. It is distinct from other worlds in our solar system because, like us, it has its own kind of rainfall, as well as an exchange between surface liquids and fog in the atmosphere. True, that liquid isn’t water, but methane, and its temperature is a pretty nippy -179˚C – but while these conditions make it a no-go holiday destination for humans, it could be home to other kinds of life.

There has been plenty of debate over whether the absence of water rules Titan out of contention, but a new study from Cornell University argues that the unique conditions of Titan could well support life after all. titan_could_hold_life

Their conclusion comes from the abundance of hydrogen cyanide (HCN) within the moon’s atmosphere. HCN molecules can link together to form polyimine – a polymer that can act as a precursor to amino acids and nucleic acids – and this is the key to their argument. Through a series of quantum mechanical calculations, the researchers showed that polyimine has the right properties to function even at the kind of cold temperatures we know to expect from Titan. In other words, there could be life out there, even without water.

Don’t get too excited, though – this merely proves it’s possible, rather than confirming that there’s life out there. As the study authors write: “

Possibilities like this, although consistent with the energetic and electronic calculations presented above, are very speculative and intended as a suggestion of the kinds of structures that might occur, rather than a specific prediction.

“Because they are impossible to form naturally in a warmer world containing water and oxygen, only future exploratory missions to Titan can test the hypothesis that natural chemical systems evolve chemical complexity in almost any circumstance.”

In other words, we won’t know until we send a lander to check it out. Last year NASA’s Innovative Advanced Concepts initiative funded a concept mission to sent a robotic submarine to explore Titan’s seas. Now that we’re more optimistic about our chances of finding life, perhaps that could be fast-tracked? Here’s a NASA 360 talk about it to get you a bit more excited: