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Life on Earth…And Els Ewhere? Activit Y 3 23 50 Activit Y 5 = Nasa S Astrobiology Institute Activit Y 5 53

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Life on Earth…And Els Ewhere? Activit Y 3 23 50 Activit Y 5 = Nasa S Astrobiology Institute Activit Y 5 53 Life on Earth …and elsewhere? Students come to class filled with questions about life on other worlds. They have seen fantastic scenarios presented on television and in films. They have read and heard about exploring and colonizing space. They have followed the drama of manned and robotic space missions. The answers to the questions that arise out of these experiences are often complex and multidimensional. How can teachers meaningfully address such questions? The hands-on activities in this Educator Resource Guide lay the con- ceptual groundwork for understanding questions fundamental to the field of astrobiology. They enable students to examine the nature of life, what it requires, its limits, and where it might be found. Through these experiences, students learn important ideas related to the search for extraterrestrial life. After completing the activities in this guide, students will understand more about the nature of life, the habitability of planets, how astrobiol- ogists gain insight into the possibility of extraterrestrial life, the interdis- ciplinary nature of astrobiology, and the difficulties and subtleties of the search for life. Not only will students have a better grasp of the con- cepts, but they will also deepen their appreciation for the many things that are necessary in order for life to arise and persist. Ultimately, the ambition of the guide is to inspire students to stay abreast of develop- ments—and perhaps even to become involved—in the search for life on other worlds. This curriculum guide was produced by TERC under a grant from the NASA Astrobiology Institute. Visit http://nai.nasa.gov/teachers/ for additional astrobiology resources for teachers, and more information on the NASA Astrobiology Institute. Version 2.0 2006 Cover images courtesy of NASA and the Hubble Heritage Team: http://heritage.stsci.edu/public/gallery/galindex.html#gallery 2 INTRODUCTION Life on Earth Activity Overview …and elsewhere? ACTIVITY What is life?...............................................................................................................5 …and elsewhere? Defining Life 1 2–3 daYS* • Compare real and fake or live and dead objects and brainstorm ideas about what life is • Refine the definition by playing 20 Questions to identify an object or organism • Test the definition by comparing “mystery” samples ACTIVITY What does life require? .............................................................................. 11 Understanding that Life Needs Water, Nutrients, and Energy 2 2 DAYS* • Grow organisms in one of 12 classroom environments and identify com- mon requirements (e.g., water, nutrients, and energy) • Design a mission to identify habitable places by searching for water, nutrients, and energy • The Math Extension—Measuring Calories ACTIVITY What makes a world habitable? ......................................................23 Assessing Planets As Candidates for Life 3 1–2 daYS* • Examine Habitability Cards, which discuss each planet and the six large moons in terms of water temperature, atmosphere, energy, and nutri- ents, and identify the top candidates for life in the solar system • The Math Extension—Inverse Square Law ACTIVITY What can life tolerate?.................................................................................37 Identifying the Range of Terrestrial Life 4 2–4 daYS* • Meet some extremophiles. What conditions do they tolerate? • Play a card game similar to Rummy. Students create a set by matching an extremophile, an extreme habitat on Earth, and an extraterrestrial habitat that may be similar to an Earth habitat. • Assemble a crew of extremophiles and target them to specific locations on a planet or moon • Debate the ethics of sending Earth life to other worlds ACTIVITY Is there life on other worlds? ...............................................................49 Determining the Chances of Extraterrestrial Life 5 1–2 daYS* • Discuss the question, “What is the chance that we are the only life in the universe?” • Determine what we need to know to predict the chances of extraterrestrial life • Make estimates for each Drake Equation term and discuss the range of predictions in the class * FOR TIME ESTIMATES, ONE DAY EQUALS A • The Math Extension—Estimation 50-MINUTE CLASS PERIOD ACTIVITY OVERVIEW 3 Using This Guide A CTIVITY Is there life on other worlds? CO NCEPTS Recommended Procedure Activity Guide 3 •The chances for life What makes a world habitable? elsewhere in the galaxy could be either high STEP To get a sense of what your students think Students typically think or low, depending on PURPOSE when they hear the term “extraterrestrial,” of “extraterrestrials” in whether one s assump- 1 ask them: terms of science fic- tions and estimates are If life is playing a game of planetary hide and seek To assess the possi- tion. Pro mpting them conservative or optimistic. to consider other Introduction Do you think there is intelligent life in our galaxy with which we can bility of life in the with us, then our job is to find it. But where in this What is the chance forms of life often solar system that we are the only communicate? In 1961, Dr. Frank Drake identified eight terms to immense solar system should we begin to look, •Finding even simple life Are there changes their answers, forms will be a break- life in the universe? such things as or at least the reasons help people think about what would have to take place for such and what should we be looking for? One way through discovery. extraterrestrials? they provide. C ONTEXT communication to be possible. astrobiologists narrow the number of possible • The large number of “hiding places” is to understand what makes a Activity 3 builds on the work the stu- stars significantly planet or moon habitable. They then look close- increases the possibility What do See what you think the chances are by making your own estimate dents have done ly at these habitable places. of extraterrestrial life. you mean by for each of the terms below. The conservative and optimistic val- defining and exam- extraterrestrials? ining life. Students ues indicate the range of opinion among scientists with regard to No life beyond Earth has ever been found. Does apply this work to each term. You can use the conservative or optimistic estimates the question of this mean that life is a rare accident that hap- SKILL S whether there is life or use another value, depending on your own intuition. pened on Earth due to an extraordinary set of cir- W ould you be on other planets and • Understand that our interested in a planet cumstances and is unlikely to happen elsewhere? moons, a question galaxy contains a large inhabited by microbes, Do you think that Currently, all other planets and moons seem to lack that people have number of stars plants, and insects? Why there are any forms or why not? long pondered and of life elsewhere in at least one major requirement for life. Despite this • Understand and that drives much of the universe? Why? fact, Europa, Mars, and possibly Titan seem to have or Estimate the terms of the the space program. Drake Equation have had conditions conducive to life. Most astrobiologists This activity also feel that, if extraterrestrial life were found, it would be bacte- familiarizes students • Calculate how many civi- STEP Have the class define the term, extraterres- In 1961, Dr. Frank with the planetary lizations with radio tech- ria-like, living beneath a planets or moon s surface, and using trial. Try to get them to broaden the mean- Drake developed an bodies in the solar nology we can chemical energy for its needs. 2 ing to include anything from microbes to equation to estimate system. communicate with plants to intelligent creatures to any living the number of other civilizations that exist in thing. our Milky Way galaxy Finding any kind of life beyond Earth would TIME that we can detect STEP be a profound discovery. It would help us Mention that astrobiology involves thinking using radio technology. 1 to 2 class periods MATERIAL S understand more about how planets and about whether or not there is extraterrestri- It does this by making 3 al life, where it might be, and how we can estimates of eight com- moons can generate the chemistry that • one Activity Guide (pages 53 and 54) learn more about it. ponent factors. Since leads to life and about the conditions that for each student we are unsure whether What to Do To estimate the number of worlds in the Milky Way life can tolerate. Furthermore, it would help STEP To have students identify the factors related there is life out there, let alone intelligent life • blank overhead trans- galaxy that have intelligent life that we can detect provide some important clues to the question to the existence of extraterrestrial life, ask with which we can parencies 4 them what information they would need to using radio technology, follow these steps: of whether life is a rare or common occurrence communicate, there is determine the probability of extraterrestrial no correct solution to • transparency markers in the universe. life. You might begin by saying, “Lets see if the equation — the value of each factor is • calculators w e can estimate how many worlds out 1 Make estimates for each of the eight terms listed there have life (or intelligent life with which open to interpretation. on the Using the Drake Equation w orkshee.t w e can communicate). What would we need to know?” Try to keep your prompting 2 Convert percentages to decimals before multiplying. 3 Multiply the estimates you made for the eight terms. The Drake Equation The number of worlds within Number of stars in the Milky Way Percent of appro- Percent of these our Galaxy that have intelli- galaxy priate stars that stars that are gent life whose radio emis- have planetary appropriate sions should be detectable XX systems X LIFE ON EARTH…AND ELS EWHERE? ACTIVIT Y 3 23 50 ACTIVIT Y 5 = NASA S ASTROBIOLOGY INSTITUTE ACTIVIT Y 5 53 A Background Reading The Recommended The Activity Guide leads stu- starts the investigation and Procedure details how to dents through an activity informs teachers about the implement the activity.
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