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        Basic Ingredients for Life

        In this lesson, students make impact craters to gain insight into how comets and asteroids deliver water and chemicals to the Earth and other places in the solar system.

        Lesson Summary


        Students make impact craters to gain insight into how comets and asteroids deliver water and chemicals to the Earth and other places in the solar system. They identify the basic features of craters and compare the craters they make with those observed in the solar system.

        This activity was adapted from:
        Impact Craters | Johnson Space Center
        From Exploring the Moon (pages 61–70).

        Think SMALL in a BIG Way | Jet Propulsion Laboratory
        From the Stardust Educator’s Guide.

        What Can Craters Tell Us About a Planet? | Jet Propulsion Laboratory
        Exploring Activity 3 from the Mars Exploration Curriculum.


        • Understand that life as we know it requires energy, water, and organic compounds
        • Discover that comets and asteroids deliver water and chemicals to planets and moons through collisions
        • Learn that evidence of these collisions can be found in craters throughout the solar system

        Grade Level: 1-6

        Suggested Time

        • One class period (approx. 20-30 minutes)

        Media Resources



        One per student or per team of 2 to 3 students:

        • A shallow box (e.g., medium-sized plastic deli container, pizza box, lid from copy paper box, aluminum pan, etc.)
        • White flour (enough to make a layer two inches deep in the box)
        • Powdered cocoa (enough to make a thin layer on the flour)
        • A flour sifter, sieve, or cheese or spice shaker (for sprinkling cocoa powder onto flour)
        • 3 balls of various sizes (1 to 4 cm), such as rubber balls or marbles in a cup

        Before the Lesson

        • Download the Basic Ingredients for Life presentation slides.
        • Fill containers two inches deep with flour.
        • Lay down an unopened trash bag, drop cloth, or large sheet of newspaper at every station.
        • Cover the flour with a layer of cocoa powder, using a flour sifter, sieve, or shaker to evenly sprinkle a thin dusting.
        • Add three or more impactors to a cup and set at each station.

        The Lesson

        Part I: Engage

        1. Ask:

        • What kinds of things do you need to keep you alive? (Humans need food, water, and air. Broadly, life as we know it requires energy, water, and organic compounds.)
        • The Earth didn’t always have abundant water and nutrients easily available to living things. What are some ideas for how a good portion of Earth’s water and nutrients got here? Here’s a hint: something delivered them from outer space. (They were delivered by comets and asteroids that had a small supply of water and nutrients. When one crashed into Earth, it added a little water and a few nutrients to Earth’s supply.)
        • We have to look for clues that collisions like these took place on Earth and in the solar system. What might evidence of a collision look like?

        2. Show the Basic Ingredients for Life presentation slides of the aftermath of other kinds of collisions to get students thinking about what caused them. End with images of craters so students can make the connection between craters and collisions. Identify key features (e.g. rim, ejecta, rays, walls, and central peaks).

        Part II: Facilitate

        3. Demonstrate how to make a crater. Explain that the white flour is a fine powder that represents the lunar regolith— the layer of loose, heterogeneous material covering the rocky surface of the moon made of dust, soil, broken rock, and other related materials. The cocoa makes the ejecta and rays from the impact much easier to see.

        4. Send each student or team to a cratering station and encourage them to change the drop height, angle of impact, and size of the impactor. As the students are making their craters, walk around and ask them to identify the rays and rim of their craters.

        Check for Understanding

        Show the Comets Bombard the Early Earth video, which explains the role that asteroids and comets played in seeding the solar system with water and chemicals. Using the questions provided, discuss comets and impact craters and what we learn from them.

        Ask: What would happen if a comet hit Earth? (It would make a crater; break into pieces; make a huge explosion; raise a cloud of dust; add material to Earth; destroy the area it hit.)

        Show the Basic Ingredients for Life presentation slides of some of Earth’s craters. Tell students that all the planets and moons in the early solar system were bombarded by comets and asteroids, and they all got similar supplies of water and nutrients. (Comets and asteroids are rich in water ice and chemicals needed by life. They delivered these materials when they crashed into the planets and moons.)

        Keep Exploring

        Guided cratering lab activity (ages 9 and up) (Optional)
        (This will add 45 minutes to the activity.)

        This comet cratering activity is from Think SMALL in a BIG Way in the Stardust Educator’s Guide (pages 6–12.) Tell students they will find out how craters are formed by doing an experiment. Group students into teams of three or four. Tell them to follow the procedure on the Stardust mission’s handout.

        Let students know:

        • The knot in the string is at 30 cm.
        • To measure the crater diameter, the students need to carefully remove the ball and measure across the middle, rim to rim. (Optional: Students can also measure the diameter of the blanket of ejected material.)
        • Before testing the next ball, smooth the cratering surface by running a card across the surface layer. If the top is too mottled in color, students may need to refresh the dusting of cocoa powder.

        Make a dry-ice comet (Optional)

        Demonstrate what a comet is made of by making one out of dry ice:

        • Find the basic recipe for a comet.
        • Watch NASA’s Create a Comet with Dry Ice video.
        • Look at Comet Basics (from Stardust mission)
          Try these two activities: Cookin’ Up a Comet, which uses dry ice (pages 2–4); and Edible Comet, which uses ice cream and toppings (pages 5 and 6.)


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