Earth science Archives - The Spacewriter's Ramblings

“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.

A ice/gas hydrate found off the coast of Oregon. In the Sea of Japan, microbes appear to have subsisted inside such a hydrate. Courtesy Wusel007, CC-by-SA 3.0

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 the ices he was studying exist on other objects orbiting the Sun.

What’s Flammable Ice?

A burning hydrate, courtesy of Office of Naval Research.

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 non-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 they 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.

A colony of tubeworms and other sea life clusters around a vent in the Galapagos Rift. Courtesy NOAA.

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.

Planetary Structure Rocks!

What science lets you look at a landscape and see its past? Why, geology, of course. Strictly speaking, geology is the study of Earth’s structures, rocks, and the way they form and change over time. However, the principles of understanding our planet that you learn when you study geology also come in handy when looking at other worlds. So, the earth science we learn in school gives us insight across time and solar system space.

I used to collect rocks as a kid. My first collection disappeared during a move, but that didn’t stop me from picking up more. These days, I have a small collection gathered from my travels from nearly every continent (except Antarctica). Each one has a tale to tell about its origins.

Rock crystal structures fascinated me, which is why I started picking them up in the first place. I noticed pretty quickly the many different shapes and structures in rocks. In 8th grade, we studied geology, which meant taking field trips. Around where I grew up, we were taught early on that millions of years ago, our region had been an ocean environment. Sometimes it was under deep water, and then, as the waters receded, the region was laced with shorelines and marshy areas. Over time, the plant and animal life was buried, and that created coal and natural gas. If you drive along the Front Range of Colorado (say from Pueblo to Cheyenne), it appears as a vast undulating plains area. In my mind’s eye, I can almost see the ocean that used to be there, long before the current Rocky Mountains formed and deformed the nearby landscapes.

A Short History of Colorado Geology

Colorado has been in the making since nearly the formation of our planet. It was once part of the massive continent of Pangaea. It moved around the planet as the plates underlying Pangaea shifted. Colorado’s “basement” rocks date back to that early period. The current Rockies, which are a very recent addition, didn’t even form until after the proto-North American continent had started to take shape.

The story of the landscape I live in exists in the rocks. Those that we see in the Rockies are an open geology book. From Boulder and Denver west, you can drive through broken shards of sandstone, mudstone, and shales, many laid down during the times when this area was part of a great ocean and waterway system. In fact, I-70 cuts through a series of uplifted layers that document those millions of years in geologic time. Very quickly, however, you get to the rocks that flowed once as lava or were heated and cooked by lava to become metamorphic rocks. The central Rockies are made largely of these types of rock.

Then, on the western slope, we get back to the layered sedimentary rocks from the ancient oceans that deposited sediments starting some 500 million years ago. The topmost layers are the youngest and date successively back to the Cretaceous oceans. They eventually drained away as the current Rocky Mountains rose in response to an event called the Laramide Orogeny. It was a period of mountain-building that helped create the Rockies and the larger outlines of the Colorado Plateau. Today I sit on a peak born during that event.

Everybody’s Geology

Your own home region has a geologic past that you can look up and learn from if you wish to understand why it looks the way it does. Mountains, plains, river valleys, islands, you name it, they all have their roots in geologic processes. When I travel cross-country, I often think about what stories the rocks in the flyover states could tell. Or the tales the Appalachians could share. Or the millennia-long legends the rocks of the Himalayas or the Alps could relate.

Applied Geology on Other Planets

The geology of other worlds has another name: planetary geology or planetary science. It lets us apply what we know about how Earth’s geology occurred to explain what we see elsewhere. Mars is a great example of this and we can read its rock record. It has regions that look like riverbeds, lake shore lines, and peaks. Many of the processes that laid down sedimentary rocks here on Earth are (or were) at work on Mars. Clearly, water did some of the work. But, the wind has done so, too, just as it does here at home. We have a few craters on Earth that formed as space rocks slammed into the surface. Mars does, too. As do the Moon, Mercury, Venus, some asteroids, and the icy worlds of the outer solar system. Even distant Pluto has a geological story to tell!

For the rocky worlds (the “terrestrials”) the story really IS in the rocks. Just as on Earth, when I can pick up a rock from the road by my house and understand its story, someday, people will do the same on Mars. The minerals and crystals all have a tale to tell, and it’s one that has been millions or billions of years in the making. That is why I like geology. It uses science to explain the world we live on and the other places in the solar system.

The Spacewriter's Ramblings

Category Archives: Earth science

Life, Flammable Ice, and Exoplanets