Education and
Public Engagement
at the Lunar and Planetary Institute
Space Exploration

Eggstronaut Drop

Modified from many sources. Other versions of this popular activity include Adventures in Rocket Science Educator Guide and Mars Pathfinder Egg Drop Challenge.

Overview

Design, create, and test a landing capsule that will safely deliver an egg, dropped from a height. This activity can be modified for any age group, and takes 60-120 minutes to complete.

What's the Point?

Materials

For the group:

For each child or small group of children:

For the facilitator:

Activity

  1. Brainstorm the factors affecting a space capsule’s landing with participants. For young children, consider simplifying this discussion and showing a demonstration or video of different landing capsules.
    • List their suggestions on a board or chart. For each factor, have children suggest how engineers might deal with it.
    • Factors could include the mass of the capsule, the size and shape of the capsule’s landing surface, the density of the atmosphere, the gravitational pull of the planet or moon, and the initial speed of the spacecraft.
    • Engineers could reduce the capsule's mass, maximize the area of the capsule’s landing surface, use a parachute or wings to take advantage of an atmosphere, use jets and rockets to slow its descent, and have a spacecraft begin its descent at a slow speed.
  2. Describe the challenge.
    • The children will design a capsule to protect a raw egg as it is dropped onto a hard surface from a high place.
    • Have them examine the materials available for building their space capsules.
    • Ask them what solutions come to mind for softening the egg's impact.
  3. Prepare the “Egg-stronauts".
    • Have the children draw a face and flight suit on their raw eggs using colored markers. They can name their Egg-stronauts at this time.
    • Place raw eggs back in egg carton.
    • Note: Have the children carefully handle their raw eggs. If you are concerned about children making a mess, you can have them wear smocks, not decorate their eggs, or use only hard-boiled eggs.
  4. Design and build a test capsule. (Some children may prefer to describe their plan instead of drawing it, as they begin building it).
    • Individually or in teams, children can draw a plan of their capsule. Remind them that their design must be based on the available materials. Make sure they each do a drawing and label the parts and list the materials used.
    • Have the children design their capsules, labeling their drawings, naming their capsules, and listing their materials. Depending on time, interest, and abilities, children can draw elevations, cutaways, or aerial views.
    • After completing their plans and getting them approved, have children gather their materials and build a test capsule. Give them a hard-boiled or plastic egg for this step. Save the raw eggs for the contest.
    •  If time allows, have children make a test drop of their capsules when they have completed construction. Use hard-boiled or plastic eggs. After the test drop, have children redesign their capsules based on test results and update the plan, noting the revisions in their designs.
  5. Finalize and lauch the capsules.
    • When the changes to their capsules are finalized, have children retrieve their Egg-stronauts from the egg carton and place them inside their capsules.
    • Proceed to the landing site (inside or outside, with a tall ladder, balcony, or stairwell), and if desired, set out a drop cloth to keep the floor/carpet clean.
    • Drop the capsules one at a time During a drop, make sure children stay out of the drop zone.
    • After each drop, allow the children to retrieve their capsule and examine their Egg-stronaut for signs of damage.
    • Have each team record its name, the kind of landing system used, and outcome of the landing.
  6. Discuss the results.
    • On a board or chart paper, list the kinds of systems the group used (e.g., parachute, air bag, wings, etc), and record the number of capsules in each category and the success rate of each category.
    • Ask the children to identify any patterns.
    • Why was it important to design your capsule on paper first? (Conserves materials, helps a team think through the problem and respond with well-considered solutions)
    • Why was it important to build and test a test capsule ? (One can rarely anticipate all the issues affecting a design)
    • What variables were there in designing your capsule? (Types of materials, weight, and strength of material, etc. )
    • What external factors may have affected the flight of your capsule? (wind, temperature, release technique)
    • How does the size and mass of the capsule affect how fast it goes and how great the impact is? (a larger mass falls faster, a larger volume increases air resistance)
    • What would happen if your capsule were launched from a greater height? (A greater impact might result with some designs. Other designs may have a softer impact due to their elements, such as a parachute, working better or for a longer period of time.)
    • How you could improve the design of your capsule? (Answers will vary)
    • What might happen to these capsules on a planet or moon with less gravity? (They would fall more slowly)
    • What might happen to these capsules on a planet or moon with less atmosphere? (Designs depending on air resistance would fall faster)
    • What might happen to these capsules on Venus where there is more air pressure and higher temperatures? (Designs depending on air resistance would fall more slowly)

Extensions

Weigh the capsules before dropping them. The lightest one that protects its egg is the most efficient. Before they begin their designs, make sure to tell the children that weight is a criterion.

Additional Facilitator Information

Capsules are intended to land people or instruments on the surface of Earth or another planet. Engineers need to be concerned with building a capsule that is strong enough to slow down quickly, can survive high temperatures, and can withstand quite a jolt when it lands.

When capsules land on Earth or other planets and moons, gravity pulls them and speeds them up. Different objects in our Solar System have different masses and different amounts of gravity. (Mars’ gravity is about 1/3 Earth's gravity, and the Moon has 1/6 of Earth’s gravity.) Capsules also experience drag as they pass through an atmosphere; the drag depends on several factors, including the air density, the shape of the capsule, and the roughness of the capsule’s surface. The speed is the combined effect of between the gravitational pull of the planet (which speeds up the capsule) and drag on the capsule (which slows it down).

When a space capsule approaches a planet's surface, it needs to slow down. If it slows down too fast, the capsule and its contents can be crushed. Engineers design capsules with a blunt shape to help it slow down, but it also causes the capsule to heat up as it passes through an atmosphere. Parachutes may also be used to create more drag and slow the capsule's descent.

As the capsule slows, much of the energy is converted to heat. Some capsules are protected by tiles to keep the heat of reentry from reaching the interior of the capsule. Capsules also have to be able to survive impact when they reach Earth's surface. The earliest capsule landings took place in the water.

How do spacecraft land on a planet's or moon's surface?
Most space capsules use parachutes to slow their descent, reduce their acceleration, and aid in a soft landing. Some capsules use both parachutes and jets that fire immediately before impact to help reduce the force of the impact. Some robotic spacecraft to Mars (Mars Pathfinder in 1997 and two Mars Exploration Rover missions in 2004) used a combination of parachutes and large airbags, which cushioned the spacecraft, to bounce along the surface before coming to rest. Spacecraft like the shuttle are designed to fly like gliders and land aerodynamically.

Landing on the Moon provided more challenges for slowing spacecraft. The Moon has no atmosphere so there is no drag on the capsule to slow its descent; parachutes will not work. Lunar landing vehicles were equipped with rocket engines that were fired by the pilot to provide lift — thrust in the opposite direction of descent — during the rapid descent to the Moon's surface.

How is our egg-drop capsule like a real spacecraft?
As an object falls toward a planet or moon, gravity pulls it, causing it to accelerate until it impacts the surface. Planets with atmospheres create friction with the spacecraft, which slows the re-entry. Children can borrow ideas used in spacecraft. For example, they can take advantage of air resistance by creating a wide base and using parachutes, wings, and propellers. They can calculate their egg's speed at impact and estimate the force generated, which would help them determine how much padding they need. Children can design padded capsules, capsules with parachutes, capsules with airbags, or virtually any type of capsule using the materials on hand.