Greenland’s Ice Sheet is Similar in Many Ways to the Solar System’s Icy Worlds and Can Teach Us How to Search for Life

Many regions on Earth are temperate, nutrient-rich, stable environments where life seems to thrive effortlessly. But not all of Earth. Some parts, like Greenland’s ice sheet, are inhospitable.

In our nascent search for life elsewhere in the Solar System, it stands to reason that we’ll be looking at worlds that are marginal and inhospitable. Icy worlds like Jupiter’s moon Europa and Saturn’s moon Enceladus are our most likely targets. These frozen worlds have warm oceans under layers of ice.

What can Greenland’s cryo-ecosystems tell us about searching for life on icy bodies like Europa and Enceladus?

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When Did Photosynthesis Begin?

Sometime around 2.4 billion years ago, a nascent planet Earth underwent one of the most dramatic changes in its history. Known as the Great Oxidation Event, this period saw Earth’s atmosphere suddenly bloom with (previously scarce) molecular oxygen. The rapid alteration of the atmosphere’s composition was nothing short of a cataclysm for some early lifeforms (at the time, mostly simple celled prokaryotes). Anaerobic species – those that dwell in oxygen-free environments – experienced a near extinction-level event. But the Great Oxidation was also an opportunity for other forms of life to thrive. Oxygen in the atmosphere tempered the planetary greenhouse effect, turning methane into the less potent carbon dioxide, and ushering in a series of ice ages known as the Huronian Glaciation. But oxygen is an energy-rich molecule, and it also bolstered diversity and activity on the planet, as a powerful new source of fuel for living organisms.

The cause of this dramatic event? The tiniest of creatures: little ocean-dwelling cyanobacteria (sometimes known as blue-green algae) that had developed a new super-power never before seen on planet Earth: photosynthesis. This unique ability – to gain energy from sunlight and release oxygen as a waste product – was a revolutionary step for so small a critter. It quite literally changed the world.

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Galactic Panspermia. How far Could Life Spread Naturally in a Galaxy Like the Milky Way?

Can life spread throughout a galaxy like the Milky Way without technological intervention? That question is largely unanswered. A new study is taking a swing at that question by using a simulated galaxy that’s similar to the Milky Way. Then they investigated that model to see how organic compounds might move between its star systems.

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Did Asteroid Impacts Provide Both the Heat and Raw Ingredients to Enable Life?

An artist's conception of an asteroid collision, which leads to how "families" of these space rocks are made in the belt between Mars and Jupiter. Credit: NASA/JPL-Caltech

This is our Great Question: How did life begin on Earth? Anyone who says they have the answer is telling tall tales. We just don’t know yet.

While a definitive answer may be a long way off—or may never be found—there are some clever ways to nibble at the edges of that Great Question. A group of researchers at Kobe University in Japan are taking their own bites out of that compelling question with a question of their own: Did the heat from asteroid impacts help life get started?

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Lightning Strikes Helped Life get an Early Start on Earth

So, you want to create life? You’re going to need some ingredients first. On Earth four billion years ago, you might find some of those ingredients in the impact craters of asteroid strikes (as long as you don’t get blown up in the blast yourself). A safer place to look, according to new research from the University of Leeds, might be in the sites of lightning strikes. Lightning is less destructive, more common, and creates equally useful minerals out of which you can build your early, single cellular life forms.

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Since Perseverance is Searching for Life, What Will it Be Looking for?

You have to be careful what you say to people. When NASA or someone else says that the Perseverance rover will be looking for fossil evidence of ancient life, the uninformed may guffaw loudly. Or worse, they may think that scientists are looking for actual animal skeletons or something.

Of course, that’s not the case.

So what is Perseverance looking for?

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The Interior of Enceladus Looks Really Great for Supporting Life

When NASA’s Voyager spacecraft visited Saturn’s moon Enceladus, they found a body with young, reflective, icy surface features. Some parts of the surface were older and marked with craters, but the rest had clearly been resurfaced. It was clear evidence that Enceladus was geologically active. The moon is also close to Saturn’s E-ring, and scientists think Enceladus might be the source of the material in that ring, further indicating geological activity.

Since then, we’ve learned a lot more about the frigid moon. It almost certainly has a warm and salty subsurface ocean below its icy exterior, making it a prime target in the search for life. The Cassini spacecraft detected molecular hydrogen—a potential food source for microbes—in plumes coming from Enceladus’ subsurface ocean, and that energized the conversation around the moon’s potential to host life.

Now a new paper uses modelling to understand Enceladus’ chemistry better. The team of researchers behind it says that the subsurface ocean may contain a variety of chemicals that could support a diverse community of microbes.

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