Finding life on Saturn's moon Titan may be more difficult than previously thought

"Are we alone?" It's the age-old question about life in the universe, one that astrobiologists and astronomers around the world are trying to answer.

While Earth is the only planet in our solar system that has an abundance of life, astronomers and space agencies are looking in our own backyard for signs that we are not alone. And many believe that the best places to search are the icy moons around two of the biggest planets, Jupiter and Saturn.

Currently, there are seven bodies in the outer solar system that are believed to have oceans beneath their crust: two of Saturn's moons, Titan and Enceladus; three of Jupiter's moons, Europa, Ganymede, and Callisto; one of Neptune's moons, Triton; and finally, Pluto.

They may have water, but do they have the chemical ingredients to create — and sustain —  life?

Recently, a study published in the journal Astrobiology, focused on the possibility of life on Titan, Saturn's largest moon. 

The study aimed to answer the question: If something slammed into Titan, creating an impact crater melt, could organics on the surface make it down to the ocean where they could support life?

The answer, unfortunately, was no.

"We found that even in the most optimistic scenario we could think of the amount of organics that makes it down there is quite small," said Catherine Neish, lead author of the study and an Earth sciences professor at Western University.

"So small that either life would be very difficult to be sustained over time, or in a slightly more optimistic scenario, maybe it's there, but it's so minimal that we need better instruments in order to detect such a very low level of activity.

"So it is not the thriving biosphere that I think we had hoped for."

However, that doesn't necessarily mean that the search for life on other icy moons — or even Titan — is dead in the water.

Shannon MacKenzie, a planetary scientist at Johns Hopkins University, said she believes that it was a very good study. However, she notes that there's a lot about Titan we just don't know.

"It's really hard to to conduct studies like this, because we don't, first of all, know what's on the surface of Titan," she said. "So you have to make an assumption about what kind of organics are mixing in that impact melt. The laboratory–based or analogues that we have studied well here on Earth, are just that — they're analogues. They're our best guess of what sitting on the surface."

Another issue for astrobiologists is that they don't know how long Titan has had its thick atmosphere that transports organics down to the surface.