While the rest of the world is rejoicing at the possibility of life on Mars, new research by scientists at Cornell University indicates that non-water-based life form could be found on Titan, Saturn’s largest moon. According to the team, computer models have revealed that the distant natural satellite might possess unique prebiotic conditions that could support some kind of life.
Bigger in size than Mercury, Titan is the largest of Saturn’s 60 known moons. Although too cold for liquid water, the moon is home to rivers, lakes and even oceans of methane, which interestingly also falls from the sky as rain. Although somewhat similar to Earth’s water cycle, the so-called methane cycle on Titan takes place at a much lower temperature of around 94 K (approx. -179.2°C). As part of a new project, researchers from Cornell University have used special computer-based simulation to study the surface conditions of Saturn’s largest moon.
Recently published in the Proceedings of National Academy of Sciences journal, the research points to the presence of a particular chemical that, the team believes, could be integral to process of formation of life. The substance, according to the scientists, is capable of serving as a catalyst in chemical reactions, absorbing energy from incident sunlight, even through the moon’s dense atmosphere. Speaking about the study, Martin Rahm, a postdoctoral student at the university and the paper’s lead author, said:
This paper is a starting point, as we are looking for prebiotic chemistry in conditions other than Earth’s… We are used to our own conditions here on Earth. Our scientific experience is at room temperature and ambient conditions. Titan is a completely different beast. So if we think in biological terms, we’re probably going to be at a dead end.
Similarities with Earth
Significantly colder than our own planet, Titan has very less oxygen, and is completely devoid of surface water. Nevertheless, Saturn’s largest moon bears many startling similarities with Earth. For instance, apart from Earth, Titan is the only celestial object with stable bodies of surface liquid, basically rivers, oceans and lakes of methane. Furthermore, it has a surface atmospheric pressure that is quite comparable to that on our planet. Scientists believe that Titan and Earth are the only two places in the entire solar system, where periodic rainfall is known to erode the ground.
For the current research, planetary scientist Jonathan I. Lunine and his team took the help of computer models to figure out what prebiotic conditions (basically, those that could support life) might be found on cosmic bodies like Titan. To that end, the scientists searched for a particular chemical, namely hydrogen cyanide, which is widely believed to be integral to the origin of life on Earth. According to previous research, hydrogen cyanide was likely a precursor to nucleic acids and amino acids, the two chemical substances that build proteins and DNA.
Hydrogen Cyanide: Precursor of life
As the team points out, data collected by NASA’ s Cassini-Huygens mission suggests that hydrogen cyanide is quite possibly the most abundant hydrogen-containing chemical present in the atmosphere of Saturn’s largest moon. In the past, laboratory experiments have shown that these molecules often join together to form special polymers known as polyimine. Rahm added:
Polyimine can exist as different structures, and they may be able to accomplish remarkable things at low temperatures, especially under Titan’s conditions.
Using the computer models, the scientists at Cornell have found out that, when present in abundance, polyimine could give rise to prebiotic conditions that could in turn support life, even in Titan’s super-cold environment. These polymers are capable of absorbing a wide spectrum of wavelengths, even the ones from the sun that penetrate the moon’s dense cloud-filled atmosphere. What is more, the substance boasts a flexible backbone, which means that it can easily adopt different shapes, such as sheets and coils.
Based on their research, the team has come to the conclusion that some of these structures could serve as catalysts for various life-forming chemical reactions. Thanks to their flexible structure, polyimine molecules retain their mobility even at very low temperatures. This, the scientists believe, could give rise to non-water-based life forms. Rahm was reported saying:
We need to continue to examine this, to understand how the chemistry evolves over time. We see this as a preparation for further exploration. If future observations could show there is prebiotic chemistry in a place like Titan, it would be a major breakthrough. This paper is indicating that prerequisites for processes leading to a different kind of life could exist on Titan, but this only the first step.
Source: Cornell University