Life, Flammable Ice, and Exoplanets

“It certainly changes how I think about things. Providing they have ice and a little heat, all those frigid cold planets at the edge of every planetary system could host tiny microhabitats with microbes building their own ‘death stars’ and making their own tiny little atmospheres and ecosystems, just as we discovered here.“

Is this a quote from a futuristic sci-fi character about a mad-scientist-type discovery? Not quite. It’s about a discovery made about something called “flammable ice”, and it raises questions about the search for life elsewhere in the solar system.

Deep underwater in the sea of Japan, microbes live happily munching salt water and oil. And, probably other things. The oil comes from deep wells, and probably some natural seeps. The microbes somehow get caught up in the flammable ice, where they create little bubbles of space to live in. As they digest (or break down) their fuel, they leave behind residues. So, far from being a weird alien civilization on another world, they’ve carved out their own living spaces right here on Earth. Granted, they live in the deep, chilly ocean, inside ice crystals, but they’re life.

That is why the quote above is so apropos. It’s from Dr. Glen T. Snyder, a scientist who found the residues. He engaged a team of other researchers to work on figuring out what was going on. His point is that if those microbes do it here on Earth, they do it on other worlds. That’s because methane clathrates exist on other objects orbiting the Sun.

What’s Flammable Ice?

To understand why this is so interesting in the search for life elsewhere, it helps to know a bit about flammable ice. It’s the technical term for “methane clathrate”. That’s a lattice of ice crystals surrounding trapped pockets of methane gas. It exists in the cold regions of the outer solar system, where water ice is fairly common. I’ve written here before about methane at other worlds and on comets. It’s possible to burn the methane even when it’s encased in an icy lattice.

Finding Flammable Ice

Methane gas and in clathrates on other worlds sounds alien, but they’re not. They can be fairly common on comets, ice moons, and even the giant planets. On Earth, they’re usually in areas where permafrost exists or in ocean sediments. They’re often in shallow deposits on Earth’s surface, which includes the seafloor. Some freshwater lakes also have methane clathrate layers, and in some places may also lay atop gaseous methane deposits. Methane is familiar to many of us who use natural gas for heating, and it’s a product of gas and oil exploration and extraction.

Methane clathrates are also known as “flammable ice” because it can burn under certain conditions. It comprises the world’s largest supply of methane, which is a greenhouse gas complicit in climate change. T here is some fear that if methane clathrates melt, they release the gas into the oceans and atmosphere. The evidence for that is still being studied. In a 2017 study, the United States Geological Survey found that methane often stays in ocean bottom sediments. It dissolves in seawater, or is converted to carbon dioxide by microbes. (Of course, the oceans do sequester a lot of CO₂, but there is also concern that it’s changing their acidity due to that. So, the release of methane may have unexpected effects. But, that’s the subject of another article, someday.)

Microhabitats In Flammable Ice

So, back to the quote above. The story behind it is pretty interesting. Snyder and other scientists studying samples of this “flammable ice” found in the Sea of Japan first found strange deposits as they were melting some of the material. The deposits contained tiny spheroids with dark cores. After much study, Snyder and his team determined that they were the leftovers from microbes munching on oil and seawater. Without getting too technical, what they found was the evidence for life inside a frozen shell of water ice, nestled inside the methane gas. Essentially, these microbes adapted to the conditions and created habitats inside the ice. In reporting their find, Dr. Snyder made the statement above. The team’s work is opening up a whole new way of understanding how life could survive on the frozen worlds of the outer solar system.

Life on Exoplanets and other Strange Places

Of course, the search for life elsewhere isn’t limited to our own solar system. As astronomers study the many worlds discovered by such missions as TESS and Kepler, and by ground-based observers, the question continues to arise: is there life out there? Not all worlds are like Earth, which we have always considered the epitome of a life-bearing planet. But, since life can exist in some pretty hostile environments, there’s no reason to assume life isn’t out there. Microbes don’t just subsist on eating flammable ice here on Earth. They also exist in some pretty hot environments, too. And, look at the clusters of life forms that swarm around deep-sea volcanic vents! Those hydrothermal vents are chimneys from undersea volcanic activity. They send out jets of superheated, mineral-rich water. And, guess what? There are life forms that think that’s a pretty good diet.

It turns out that several worlds in our solar system very likely have deep-ocean warm regions, so if life could exist there. And, if similar conditions exist on worlds around other stars, it’s likely to be there, too. Of course, we have NO proof of any life beyond our planet. Yet. But, it’s coming. And, with studies like the one that Dr. Snyder and colleagues did, scientists will have a better handle on what to look for when they do further work searching out life in other places.

If you want to get into the nitty-gritty of the finding, check out Snyder, et al’s paper, Evidence in the Japan Sea of microdolomite mineralization within gas hydrate microbiomes. I first found the http://astrobiology.com/2020/02/methane-hydrate-discovery-offers-clues-to-life-on-other-planets.htmlstory in a blog entry at the Astrobiology Web page.

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