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Comic-style illustration of a DNA strand exploding apart from a yellow shiny, semitransparent ball slicing through its bars

3.2. What does life need for survival?

A core learning question from the Astrobiology Learning Progressions

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3.1. What are the characteristics of life?

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3.3. What determines if a planet can have life?

Grades K-2 or Adult Naive Learner

Our families and our pets need some things like food, water, a place to live, and a place to sleep in order to stay alive. Let’s think beyond our homes and consider what other living things need to stay alive. Do other living things need the same things that we need?

They may eat different foods or sleep somewhere other than in a house but all living things have certain needs. If we think about places other than Earth, we can guess that living things in those places would need food and water, too. So, to find possible alien life, we explore places that may have any type of food and water to see what we can discover there.

Portrait photo of Comic-style illustration of a DNA strand exploding apart from a yellow shiny, semitransparent ball slicing through its bars
All life on Earth is made up of DNA and requires several basic needs to survive, such as water and sources of energy. A protective atmosphere is also needed for life to survive in order to protect it from UV radiation from its host star. Too much radiation can cause damage to DNA.
NASA/Aaron Gronstal

Grades 3-5 or Adult Emerging Learner

All of the living things that we know of need food and water in order to stay alive. Although different animals and plants might survive better in different places, such as deer living in forests and whales living in the ocean, they all need food and water to survive. All living things, including animals, plants, fungi, and things too small to even see, need food and water. Therefore, when searching for life beyond Earth, we look for places that have liquid water and nutrients. Amazingly, there are even some living things on Earth that can survive in areas too severe for people, such as hot springs, deep underground, in caves, or at the bottom of the ocean. When we plan exploration beyond Earth in the search for possible life, we pay close attention to places that have water and the kinds of “food” that these hardy Earth living things use to survive.

Portrait photo of Comic-style illustration of a DNA strand exploding apart from a yellow shiny, semitransparent ball slicing through its bars
All life on Earth is made up of DNA and requires several basic needs to survive, such as water and sources of energy. A protective atmosphere is also needed for life to survive in order to protect it from UV radiation from its host star. Too much radiation can cause damage to DNA.
NASA/Aaron Gronstal

Grades 6-8 or Adult Building Learner

Through our own experiences, it is clear that all living things on Earth need to acquire energy and have available water in order to stay alive. Different biomes on Earth have types of plants, animals, fungi, and microbes that survive better in certain environments. However, if we examine any living organism, they all need food and water, in some form, to survive.

When we want to consider if life possibly exists beyond Earth, we use the fact that life as we know it needs energy and water to guide our explorations. For instance, finding places beyond Earth that have liquid water and sources of energy is really important if we want to find alien life.

But we don’t have to just think about things like plants and animals that live in the same kinds of environments that we do. For instance, there are some organisms on Earth that can survive and even flourish in extreme conditions. These can be places like hot springs or glaciers or places that are really dry or really salty or acidic. The organisms who live in these kinds of places are called “extremophiles”. By learning about extremophiles, we can widen the search for possible alien life to even more environments beyond Earth.

Portrait photo of Comic-style illustration of a DNA strand exploding apart from a yellow shiny, semitransparent ball slicing through its bars
All life on Earth is made up of DNA and requires several basic needs to survive, such as water and sources of energy. A protective atmosphere is also needed for life to survive in order to protect it from UV radiation from its host star. Too much radiation can cause damage to DNA.
NASA/Aaron Gronstal

Grades 9-12 or Adult Sophisticated Learner

Through our own experiences, it is clear that all living things on Earth need to acquire energy and have available water in order to stay alive. Different biomes on Earth have types of plants, animals, fungi, and microbes that survive better in certain environments. However, if we examine any living organism, they all need food and water, in some form, to survive.

When we want to consider if life possibly exists beyond Earth, we use the fact that life as we know it needs energy and water to guide our explorations. For instance, finding places beyond Earth that have liquid water and sources of energy is really important if we want to find alien life.

But we don’t have to just think about things like plants and animals that live in the same kinds of environments that we do. For instance, there are some organisms on Earth that can survive and even flourish in extreme conditions. These can be places like hot springs or glaciers or places that are really dry or really salty or acidic. The organisms who live in these kinds of places are called “extremophiles”. By learning about extremophiles, we can widen the search for possible alien life to even more environments beyond Earth.

Portrait photo of Comic-style illustration of a DNA strand exploding apart from a yellow shiny, semitransparent ball slicing through its bars
All life on Earth is made up of DNA and requires several basic needs to survive, such as water and sources of energy. A protective atmosphere is also needed for life to survive in order to protect it from UV radiation from its host star. Too much radiation can cause damage to DNA.
NASA/Aaron Gronstal