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.
Disciplinary Core Ideas
PS1.B: Chemical Reactions: Chemical processes, their rates, and whether or not energy is stored or released can be understood in terms of the collisions of molecules and the rearrangements of atoms into new molecules, with consequent changes in the sum of all bond energies in the set of molecules that are matched by changes in kinetic energy. (HS-PS1-4, HS-PS1-5)
PS3.A: Definitions of Energy: Energy is a quantitative property of a system that depends on the motion and interactions of matter and radiation within that system. That there is a single quantity called energy is due to the fact that a system’s total energy is conserved, even as, within the system, energy is continually transferred from one object to another and between its various possible forms. (HS-PS3-1, HS-PS3-2) At the macroscopic scale, energy manifests itself in multiple ways, such as in motion, sound, light, and thermal energy. (HS-PS3-2, HS-PS3-3)
PS4.B Electromagnetic Radiation: Electromagnetic radiation (e.g., radio, microwaves, light) can be modeled as a wave of changing electric and magnetic fields or as particles called photons. The wave model is useful for explaining many features of electromagnetic radiation, and the particle model explains other features. (HS-PS4-3) When light or longer wavelength electromagnetic radiation is absorbed in matter, it is generally converted into thermal energy (heat).
LS1.A: Structure and Function: Feedback mechanisms maintain a living system’s internal conditions within certain limits and mediate behaviors, allowing it to remain alive and functional even as external conditions change within some range. Feedback mechanisms can encourage (through positive feedback) or discourage (negative feedback) what is going on inside the living system. (HS-LS1-3)
LS2.B: Cycles of Matter and Energy Transfer in Ecosystems: Photosynthesis and cellular respiration (including anaerobic processes) provide most of the energy for life processes. (HS-LS2-3)
PS3.D: Energy in Chemical Processes: The main way that solar energy is captured and stored on Earth is through the complex chemical process known as photosynthesis.
LS2.A: Interdependent Relationships in Ecosystems: Ecosystems have carrying capacities, which are limits to the numbers of organisms and populations they can support. These limits result from such factors as the availability of living and nonliving resources and from such challenges such as predation, competition, and disease. Organisms would have the capacity to produce populations of great size were it not for the fact that environments and resources are finite. This fundamental tension affects the abundance (number of individuals) of species in any given ecosystem. (HS-LS2-1, HS-LS2-2)
LS2.C: Ecosystem Dynamics, Functioning, and Resilience: A complex set of interactions within an ecosystem can keep its numbers and types of organisms relatively constant over long periods of time under stable conditions. If a modest biological or physical disturbance to an ecosystem occurs, it may return to its more or less original status (i.e., the ecosystem is resilient), as opposed to becoming a very different ecosystem. (HS-LS2-2, HS-LS2-6)
LS2.D: Social Interactions and Group Behavior: Group behavior has evolved because membership can increase the chances of survival for individuals and their genetic relatives. (HS-LS2-8)
LS4.C: Adaptation: Natural selection leads to adaptation, that is, to a population dominated by organisms that are anatomically, behaviorally, and physiologically well suited to survive and reproduce in a specific environment. That is, the differential survival and reproduction of organisms in a population that have an advantageous heritable trait leads to an increase in the proportion of individuals in future generations that have the trait and to a decrease in the proportion of individuals that do not. (HS-LS4-3, HS-LS4-4) ▪ Changes in the physical environment, whether naturally occurring or human induced, have thus contributed to the expansion of some species, the emergence of new distinct species as populations diverge under different conditions, and the decline – and sometimes the extinction – of some species. (HS-LS4-6)
ESS1.C: The History of Planet Earth: Although active geologic processes, such as plate tectonics and erosion, have destroyed or altered most of the very early rock record on Earth, other objects in the solar system, such as lunar rocks, asteroids, and meteorites, have changed little over billions of years. Studying these objects can provide information about Earth’s formation and early history. (HS-ESS1-6)
ESS2.A: Earth Materials and Systems: Evidence from deep probes and seismic waves, reconstructions of historical changes in Earth’s surface and its magnetic field, and an understanding of physical and chemical processes lead to a model of Earth with a hot but solid inner core, a liquid outer core, a solid mantle and crust. Motions of the mantle and its plates occur primarily through thermal convection, which involves the cycling of matter due to the outward flow of energy from Earth’s interior and gravitational movement of denser materials toward the interior. (HS-ESS2-3
ESS2.C: The Roles of Water in Earth’s Surface Processes: The abundance of liquid water on Earth’s surface and its unique combination of physical and chemical properties are central to the planet’s dynamics. These properties include water’s exceptional capacity to absorb, store, and release large amounts of energy, transmit sunlight, expand upon freezing, dissolve and transport materials, and lower the viscosities and melting points of rocks. (HS-ESS2-5)
ESS2.D: Weather and Climate: The foundation for Earth’s global climate systems is the electromagnetic radiation from the Sun, as well as its reflection, absorption, storage, and redistribution among the atmosphere, ocean, and land systems, and this energy’s re-radiation into space. (HS-ESS2-2)
Systems and System Models: Models (e.g., physical, mathematical, computer models) can be used to simulate systems and interactions — including energy, matter, and information flows — within and between systems at different scales. (HS-LS2-5)
3-5, 6-8, 9-12 Marsbound! In this NGSS aligned activity (three 45-minute sessions), students become NASA project managers and design their own NASA mission to Mars. Mars is significant in astrobiology and more needs to be learned about this planet and its potential for life. Students create a mission that must balance the return of science data with mission limitations such as power, mass and budget. Risk factors play a role and add to the excitement in this interactive mission planning activity. Arizona State University/NASA. http://marsed.asu.edu/lesson_plans/marsbound
4-12 Finding Life beyond Earth, Activity 4: Extreme Living (page 22). Using cards that show extremophiles and some of Earth’s extreme environments, kids match a microbe to an extreme environment in which it could live. https://d43fweuh3sg51.cloudfront.net/media/assets/wgbh/nvfl/nvfl_doc_collection/nvfl_doc_collection.pdf
4-12 Finding Life beyond Earth, Activity 5: Home Sweet Home (page 25). Students choose a card describing one of six possible planetary environments and design a form of life that can thrive in the conditions outlined on the card. https://d43fweuh3sg51.cloudfront.net/media/assets/wgbh/nvfl/nvfl_doc_collection/nvfl_doc_collection.pdf
5-12 Astrobiology Graphic Histories. Issue 2: Missions to Mars. These astrobiology related graphic books are ingenious and artfully created to tell the story of astrobiology in a whole new way. The complete series illustrates the backbone of astrobiology from extremophiles, to exploration within and beyond the solar system. This issue covers the ups and downs of the exploration of Mars and new missions to the red planet. NASA. https://astrobiology.nasa.gov/resources/graphic-histories/
5-12 Europa: Ocean World. In this short video (4 minutes), students learn that scientists believe there is an ocean hidden beneath the surface of Jupiter’s moon Europa. NASA-JPL astrobiologist Kevin Hand explains why scientists are so excited about the potential of this ice-covered world to answer one of humanity’s most profound questions. JPL/NASA. https://www.youtube.com/watch?v=kz9VhCQbPAk
6-8 or 9-12 Astrobiobound! This lesson engages students by giving them the opportunity to identify a significant target of interest in astrobiology and allowing them to plan their own NASA mission within our Solar System. This simulation follows the same considerations and challenges facing NASA scientists and engineers as they search for life in our Solar System and as they try to answer this compelling question, Are we Alone?. NASA/Arizona State University. https://marsed.asu.edu/lesson-plans/astrobiobound
6-12 Mars: The Xtreme-O-philes. Students in grades 6-12 use real scientific data to gain knowledge about the various types of extremophiles found on Earth and use that information to correlate to Mars’ environmental conditions, both past and present. Students then determine the most likely and interesting candidate landing sites for future Mars exploration, specifically missions searching for potential life. Arizona State University/NASA. http://marsed.asu.edu/content/xtreme-o-philes
6-12 Astrobiology Math. This collection of math problems provides an authentic glimpse of modern astrobiology science and engineering issues, often involving actual research data. Students explore concepts in astrobiology through calculations. Relevant topics include Lakes of Methane on Titan (page 53) and How Hot is That Planet? (page 39). NASA. https://www.nasa.gov/pdf/637832main_Astrobiology_Math.pdf
9-12 Microbial Life Educational Resources. A WebQuest Exploring the Life and Ecology of Mono Lake. The waters of Mono Lake were once considered to be virtually lifeless. Today, however, we know the lake is teeming with life. Mono Lake is teaching scientists about life’s ability to tolerate extreme conditions. In this interactive web quest, students explore this extreme environment and the extremophiles that live there. The website also contains a variety of educational and supporting materials for students and teachers of microbiology. There is information about microorganisms, extremophiles and extreme habitats, as well as links to online information about the ecology, diversity, and evolution of microorganisms. Carlton College. https://serc.carleton.edu/microbelife/k12/alkaline/WQintro.htmlhttps://serc.carleton.edu/microbelife/index.html