It's life Geoff, but not as we know it (Day 286)

It's life Geoff, but not as we know it (Day 286)

9th March 2015

Chemical engineering can offer a life full of surprises, but I can honestly say that I never imagined the discipline being used to describe an extra-terrestrial life form.

I have already discussed our chemical engineering colleagues who are astronauts (see ‘A path to the stars’) and possible methods of powering space missions (see ‘Human waste could power a lunar space mission’); but the reaches of space are endless.

Our imaginations for other lifeforms are often limited by the assumption that water is a requirement for life. Whilst this is true on Earth, in other, colder worlds life may exist beyond the realm of water-chemistry.

Titan has seas, like Earth, but unlike Earth these seas are filled with liquid methane. The team suggest that Titan could support methane-based, oxygen-free cells that are able to metabolise, reproduce and complete all the other functions necessary for life - as on Earth.

Photo Credit | Cornell Graduate student James Stevenson, astronomer Jonathan Lunine and chemical engineer Paulette Clancy, with a Cassini image of Titan in the foreground of Saturn, and an azotosome, the theorized cell membrane on Titan

This research is led by chemical molecular dynamics expert Paulette Clancy, Professor of Chemical and Biomolecular Engineering, working with James Stevenson, a graduate student in chemical engineering and Jonathan Lunine, Professor of Physical Sciences in the College of Arts and Sciences’ Department of Astronomy.

They recently published their work in the journal Science Advances under the title ‘Membrane alternatives in worlds without oxygen: Creation of an azotosome’, the paper outlines their theoretical cell membrane composed of small organic nitrogen compounds.

The work began when Jonathan, intrigued by the idea of methane-based lifeforms, asked for help from his chemical engineering colleagues at Cornell, and Paulette stepped up.

It may surprise some people that this work was led by chemical engineers, but Paulette clearly explains why chemical engineering is so useful to a multitude of disciplines: “We’re not biologists, and we’re not astronomers, but we had the right tools.

“Perhaps it helped because we didn’t come in with any preconceptions about what should be in a membrane and what shouldn’t. We just worked with the compounds that we knew were there and asked, ‘If this was your palette, what can you make out of that?’”

Life on Earth is reliant on a membrane with a phospholipid bilayer, which is a strong, yet permeable, water-based structure that holds the organic matter of all cells.

Due to this dependence on water, these cells can only survive in the narrow band around the sun in which liquid water can exist. But what if these cells weren’t water based, and instead used something with a much lower freezing point like methane?

Picture Credit | James StevensonA representation of a 9-nanometer azotosome, about the size of a virus, with a piece of the membrane cut away to show the hollow interior

That is the premise behind this work. The cells the team theorised, which they name azotosomes, are made up of nitrogen, carbon and hydrogen – all of which are found in Titan’s seas. They show the same stability and flexibility as their Earth equivalents.

Paulette says that the next step is to try and demonstrate how their cells would behave in a methane environment, and what their processes for reproduction and metabolism might be.

Jonathan is excited by the prospect of one day being able to test these ideas in Titan’s seas. He thinks of “someday sending a probe to float on the seas of this amazing moon and directly sampling the organics”.

Whereas James is just proud that this work is the “first concrete blueprint of life not as we know it”.

If you are working with the possibilities and problems of extra-terrestrial engineering, why not get in touch and tells us about your out-of-this-world research!