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A comic-style image of a meteorite explosion is seen in fiery red, yellow, and orange colors with black silhouettes of dinosaurs in the foreground.

6.2. What types of conditions can life survive in?

A core learning question from the Astrobiology Learning Progressions

Astrobiology Learning Progressions Navigation

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6.1. How did life on Earth come to occupy so many different environments?

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6.3. Are there environments beyond Earth that could be habitable?

Grades K-2 or Adult Naive Learner

We think about our homes and many are very nice and warm with food and water and everything we need to grow and be safe. When we investigate living things on our planet we notice that there are things living in lots of different places that may not be so fun for us to live in. For instance, some things live in really cold places that are very icy while other things live in hot deserts. We wouldn’t do so well if we lived in those places.

The more we investigate the creatures here we see that living things can be found just about everywhere on Earth. Do you think there might be other places out there beyond Earth that have some similar places where we might find living things?

Portrait photo of A comic-style image of a meteorite explosion is seen in fiery red, yellow, and orange colors with black silhouettes of dinosaurs in the foreground.
Life survives extreme heat, freezing cold, crushing pressure, toxic chemicals, and high radiation. Even after a massive asteroid wiped out the dinosaurs, life adapted and thrived, proving how resilient living things are.
NASA/Aaron Gronstal

Grades 3-5 or Adult Emerging Learner

We think about our homes and many are very nice and warm with food and water and everything we need to grow and be safe. When we investigate living things on our planet we notice that there are organisms living in lots of different places that may not be very well suited for us humans. For instance, some things live in really cold places that are very icy while other things live in hot deserts. There are organisms that live on the bottom of the ocean or who spend most of their time high up in the sky. While we wouldn’t do so well if we lived in those places, the things that do live there are well suited to those environments. For instance, the thick, fatty skin of a whale lets it live in the cold waters of the ocean, an owl’s eyes are adapted to let it see really well at night, and butterflies have camouflage and even disguises on their outsides to avoid being eaten.

The more we investigate the creatures here we see that living things can be found just about everywhere on Earth. Do you think there might be other places out there beyond Earth that have some similar places where we might find living things? What do you think life here on our planet can teach us about what those other things might be like? We definitely need to continue to study and discover life on Earth in order to understand where life beyond Earth may exist.

Portrait photo of A comic-style image of a meteorite explosion is seen in fiery red, yellow, and orange colors with black silhouettes of dinosaurs in the foreground.
Life survives extreme heat, freezing cold, crushing pressure, toxic chemicals, and high radiation. Even after a massive asteroid wiped out the dinosaurs, life adapted and thrived, proving how resilient living things are.
NASA/Aaron Gronstal

Grades 6-8 or Adult Building Learner

When we think about life on this planet most of us will first think about things like people and other large mammals, maybe fish and birds, and plants. But there are definitely lots of different kinds of living things here on Earth. There are mushrooms and algae and corals and grasshoppers and microorganisms that live in the soil and weird looking fish that live deep in the ocean. Life is just about everywhere on the surface of Earth and can definitely be found in places that aren’t so good for humans. Do you think you could live well deep under the ocean without a submarine? There’s a reason why we humans don’t naturally live in really cold places like on top of glaciers or really hot places like in Death Valley.

Research on Earth has actually uncovered a wide variety of harsh conditions where life can still be found thriving. Places like hot springs and hydrothermal vents and inside of glaciers and deep under the ground and on the surfaces of rocks in deserts. We call the organisms that live in these kinds of places “extremophiles,” since the conditions in which they live are way too extreme for us humans. There are extremophiles that survive in areas of extreme temperatures and pressures, where it’s really acidic or not acidic at all, where it’s super salty, where it’s really dry, with lots of radiation, and even in places where the chemistry would be toxic for humans to live.

Finding organisms that live in so many different kinds of environments on Earth tells us that there are lots of potential places where alien life might exist if it’s out there. For instance, there are places in our solar system where some of the kinds of living things here on Earth might be able to survive. These are places like Mars and the moons Europa and Enceladus. And there may be lots of other exoplanets out there in the galaxy that have conditions where living things that we know of could thrive. Understanding the conditions where we can find life here on Earth will help us in looking for possible signs of other life out there in the universe.

Portrait photo of A comic-style image of a meteorite explosion is seen in fiery red, yellow, and orange colors with black silhouettes of dinosaurs in the foreground.
Life survives extreme heat, freezing cold, crushing pressure, toxic chemicals, and high radiation. Even after a massive asteroid wiped out the dinosaurs, life adapted and thrived, proving how resilient living things are.
NASA/Aaron Gronstal

Grades 9-12 or Adult Sophisticated Learner

When we talk about life on Earth most of us will first think about things like people and other large mammals, maybe fish and birds, and plants. But there are definitely lots of different kinds of living things here on Earth. There are mushrooms, algae, corals, and grasshoppers. There are so many microbes living in the soil and in lakes and oceans and inside of other organisms (including us). Life is just about everywhere on the surface of Earth and can definitely be found in places where we humans simply cannot live. There are so many possible conditions for life as we know it to thrive.

Research has even uncovered a wide variety of harsh conditions where life can still be found thriving. For instance, in 1977 a team of researchers in a submersible in the Atlantic found arguably one of the most important discoveries of the 20th century: hydrothermal vents, with thriving ecosystems that are not dependent on the Sun for energy. The basis for life in this extreme environment comes from chemical reactions between the ocean water and the rocks on the ocean floor. We’ve now discovered organisms living in places like hot springs and hydrothermal vents, inside of glaciers and deep under the ground, and on the surfaces of rocks in deserts. We call the organisms that live in these kinds of places “extremophiles”, since the conditions in which they live are way too extreme for humans. There are extremophiles that survive in areas of extreme temperatures and pressures, where it’s really acidic (low pH) or not acidic at all (high pH; also called “basic”), where the salinity is really high, where it’s really dry, with lots of ionizing radiation, and even in places where the chemistry would be toxic for humans to live.

Finding organisms that live in so many different kinds of environments on Earth tells us that there are lots of potential places where alien life might exist if it’s out there. For instance, there are places in our solar system where some of the kinds of living things here on Earth might be able to survive. These are places like Mars and the moons Europa and Enceladus. There may be lots of other exoplanets out there in the galaxy that have conditions where living things that we know of could thrive. As we continue searching for possible places where alien life may exist, it’s important to consider the conditions where we find life on Earth but also important to remember that there may be living things that thrive in places where even Earth life can’t exist. Understanding the conditions where we can find life here on Earth will most certainly help us in looking for possible signs of other life out there in the universe.

Portrait photo of A comic-style image of a meteorite explosion is seen in fiery red, yellow, and orange colors with black silhouettes of dinosaurs in the foreground.
Life survives extreme heat, freezing cold, crushing pressure, toxic chemicals, and high radiation. Even after a massive asteroid wiped out the dinosaurs, life adapted and thrived, proving how resilient living things are.
NASA/Aaron Gronstal

Storyline Extensions

What makes an extremophile extreme?
The word “extremophile” is sometimes seen as being a little anthropocentric. That’s because the one thing that makes extremophiles extreme is that they live in extreme environments relative to us and most of the living things that we commonly interact with. Extremophiles live in extremes of temperature and pressure and acidity and such, but what about billions of years ago? Just before the rise of oxygen in our atmosphere, for instance, the things that could breathe oxygen would have been the extremophiles. That’s enough to make us wonder what we might find if/when we meet alien life. Alien life might seem to live in an extreme way compared to how we live here on Earth, but does that make that life “extreme”? A fun thought experiment is to ask yourself what if there are lots of worlds with alien life and most of those aliens are all alike but they’re all very different from us. Wouldn’t that then make us the extremophiles?