Example illustration of the touchdown activity

Overview

In this challenge, students will use what they know and can investigate about gravity, motion, and forces to design and build a shock-absorbing system that will protect two "astronauts" when they land. Just as engineers had to develop solutions for landing different vehicle types on the moon and Mars, students will follow the engineering design process to design and build a shock-absorbing system out of paper, straws, and mini-marshmallows; attach their shock absorber to a cardboard platform; and improve their design based on testing results.

Materials

Management

  • Read the challenge sheet and activity details to become familiar with the activity.

  • Gather the materials above for each group of 3-4 students

  • Suggestion: prior to student arrival, assemble a class set of above materials in gallon-sized resealable plastic bags for quick distribution.

Background

Landing on the moon is tricky. Since a spacecraft can go as fast as 18,000 miles per hour (29,000 km per hour) on its way to the moon, it needs to slow down. Then it needs to land gently. And if there are astronauts on board, the lander needs to keep them safe, too. Similarly, spacecraft on their way to Mars may be traveling as fast as 13,000 miles per hour (21,000 km per hour) when they reach the red planet and need to slow down to land safely on the surface.

Procedures

  1. Introduce the challenge (5 minutes)

    1. Tell kids why a spacecraft that can land gently is important for getting astronauts to and from the moon safely.
      NASA is looking for safe landing sites on the moon. Once they find one, they need to design and build a spacecraft that can land there without injuring astronauts or damaging the spacecraft. Today you’ll make a lander—a spacecraft that can land safely when you drop it on the floor. As you test, you’ll find ways to make it work better. Improving a design based on testing is called the engineering design process.

    2. Show kids the spring made out of an index card.
      When you jump off a high step, you bend your back and knees to absorb some of the energy and break your fall. That’s what a shock absorber does—absorbs the energy of an impact. Soft things, like marshmallows, cotton balls, foam, and bubble wrap absorb shock well. You can also use paper, like this index card made into a spring by folding it like an accordion.

  2. Brainstorm and design (10 minutes) - Distribute the challenge sheet. Discuss the questions in the "Brainstorm and Design" section.

    1. What kind of shock absorber can you make from these materials to help soften a landing? Mini-marshmallows can serve as soft footpads. Cards can be folded into springs. Straws can provide a flexible structure. Rubber bands can flex and hold things together.

    2. How will you make sure the lander doesn’t tip over as it falls through the air? Making the parts below the platform weigh more than the parts on the top helps the lander fall straight down. Also, it helps to evenly distribute the weight on top of the platform.

  3. Build, test, evaluate and redesign (35 minutes)

    • Instruct students to follow the directions in the "Build" section of the challenge sheet.

      1. Design a shock-absorbing system - Think springs and cushions.

      2. Put your spacecraft together - Attach the shock absorbers to the cardboard platform.

      3. Add a cabin for the astronauts - Tape the cup to the platform. Put two astronauts (the large marshmallows) in it. Note: The cup has to stay open -- no lids!

      4. Test, evaluate and redesign - Drop your lander from a height of one foot (30 cm). If the "astronauts" bounce out, figure out ways to improve your design. Study any problems and redesign.

    • Help students with any of the following issues. For example, if the lander:

      • Tips over when it drops: Move the cup slightly away from the side that’s tipping. Or, reposition the parts of the shock-absorbing system to better balance the weight.

      • Bounces instead of landing softly: Change the size, position, or the number of shock-absorbing parts. Kids can also add mini-marshmallows for landing-pad feet. Or, they can use marshmallows at key junctions in the lander’s frame to help absorb energy.

  4. Discuss what happened (10 minutes) - Have the kids show each other their landers and talk about how they solved any problems that came up. Emphasize the key ideas in the challenge by asking the discussion questions below.

Discussion

  • What forces affected your lander as it fell?
    It accelerated [sped up] as it fell due to the pull of gravity. Air also pushed on it, and this air resistance slowed it down.

  • After testing, what changes did you make to your lander?
    (Answers will vary.)

  • Engineers’ early ideas rarely work out perfectly. How does testing help them improve a design?
    Testing helps you see what works and what doesn’t. Knowing this lets you improve a design by fixing the things that aren’t working well or could work even better.

  • What did you learn from watching others test their landers?
    (Answers will vary. But in general, kids will see that there are many ways to successfully tackle a challenge.)

  • The moon is covered in a thick layer of fine dust. How might this be an advantage? A disadvantage?
    If the dust layer is soft, it would help cushion a landing. However, if it is too soft, a lander could sink into it and get stuck. Also, the lander’s rocket engine could send up clouds of dust, which could get into the machinery and cause it to jam or malfunction.)

Extensions

  • Hold a“ How High Can You Go?” contest.
    Have kids drop their landers from two feet. Eliminate all landers that bounce out their “astronauts.” Next, raise the height to three feet. Continue in this fashion until a winner emerges. You can also increase the challenge by having kids add a third marshmallow “astronaut” to their cups.

  • Test springs of different sizes.
    Have kids see if the number of folds in an index card makes a difference in the amount of force the spring can absorb. Have them fold index cards with two, four, and six folds. Have them test to see how much of a difference these different springs make in how softly a lander touches down.