Explore! Life on Mars

Protecting Life: The Martian Challenge

Adapted from Imaginary Martians, Destination:  Mars, NASA Johnson Space Center, 2002, and the Space Radiation unit of Explore:  Health in Space, Lunar and Planetary Institute, 2006.


During this 60-minute activity, children ages 8–13 create their own “martian” using craft materials and UV beads. They will explore how UV radiation from the Sun can affect living things, comparing conditions on Earth and Mars, and then discuss ways in which organisms may protect themselves from UV radiation. They will then take part in a Mars Creature Challenge, where they will change their creature to help it survive harsh UV conditions — like on Mars. They will then test their Mars creatures by subjecting them to different environmental conditions to see how well they “survive” in a martian environment. This investigation will explore shelter and protection as one of life’s requirements and how Earth’s atmosphere protects life from harmful UV radiation.

This activity may be split into a two-part series of activities, 30 minutes each, if needed.

What's the Point?

  • Ultraviolet radiation comes from the Sun.
  • Ultraviolet radiation from the Sun travels through space.
  • The blanket of Earth’s atmosphere protects us from much of the Sun’s ultraviolet radiation.
  • The atmosphere of Mars does not protect its surface from ultraviolet radiation. Earth is protected but Mars is not.
  • Mars is harsh: dry, very cold, a thin atmosphere, and lots of UV radiation.
  • While some ultraviolet radiation is necessary, too much can harm humans (and other living organisms).
  • Life needs protection from ultraviolet radiation.
  • Life on Mars would have to be able to withstand harsh conditions, including exposure to ultraviolet radiation.
  • There are ways in which we can protect ourselves from harmful UV radiation.
  • Be creative, design, and protect a “martian.”
Tips for Engaging Girls in STEM:
  • Spark initial interest in the topic. In this case, by engaging the children’s natural curiosity, imagination, and interest in alien life, giving them the opportunity to design their own version of a “martian.”
  • Embed activities in interesting contexts. For 8–13-year-olds, use real-world problems like how to change their creature so that it may survive (Part 2 of this activity). Girls are motivated by projects they find personally relevant and meaningful.
  • Allow children to approach the activities in their own way. Girls are motivated when they can approach projects in their own way, applying their creativity, unique talents, and preferred learning styles. This activity allows the children freedom in the design and creation to their “martian.”
  • Use project-based learning, group work, innovative tasks, and technology (i.e., web) to help engage children. Girls enjoy hands-on, open-ended projects and investigations. This activity (particularly Part 2) requires the children to collaborate to complete the survival challenge.
  • Provide opportunities for participants to engage in activities to develop their spatial skills, such as constructing and engineering projects. This activity provides an opportunity for children to design, build, and draw.


For the large group:

For each child:

  • 1 pen/pencil
  • 1 pair of scissors
  • tape and/or glue

Activity Part 1:

  • 3 UV beads (can be found in craft stores; other sources listed below)
  • 2 non-UV beads
  • 2 pipe cleaners
  • various craft items for constructing a creature, such as Styrofoam balls, felt, foil, additional pipe cleaners, small milk cartons, empty small water bottles, colored card stock, old CDs, pompoms, and colored yarn

Activity Part 2:

  • 1 Mars creature (should have been made during Part 1 of the activity)
  • various materials that will “protect” the Mars creature from ultraviolet radiation, for example, construction paper of different colors (green or blue offers the best protection), foil, plastic wrap (of various colors), paper sunglasses (may be obtained from an optometrist), sunscreen (try different SPFs), masking tape, paper, cloth, etc.; you may even wish to include containers of water for the children to experiment with (outside perhaps?)
  • optional (recommended):  NAI Extremophile Trading Cards
  • optional:  1 copy of Extreme-O-File:  Protecting Life activity pages
  • optional:  1 copy of Life on Mars? (extremophile) Trading Cards and/or Scientist Spotlight pages
    Trading Cards (large file, 34 MB)
    Trading Cards (small file, 7 MB)
  • optional:  1 hair dryer
Sources for UV Beads:

Educational Innovations
Phone:  1-888-912-7474/Fax:  203-229-0740

Steve Spangler Science
Phone:  1-800-223-9080

For the facilitator:

  • background information
  • shopping list
  • outdoor area where the children can spread out a little, preferably with both shady and sunny areas
  • area indoors where the children can move around and interact with each other


  • Review the activity procedures, activity pages, and science background information.
  • Locate an outdoor area close by that has both shady and sunny spots, if possible.
  • Prepare an area indoors with the craft materials, where the children will create their Mars creatures.
  • Optional:  Print copies of the Extreme-O-File: Protecting Life activity pages and/or Life on Mars? Trading Cards (extremophiles) and Scientist Spotlight pages.
    Trading Cards (large file, 34 MB)
    Trading Cards (small file, 7 MB)

Facilitator’s Note:  Radiation and the Electromagnetic Spectrum
Light and heat are part of the spectrum of energy — or radiation — our Sun provides. We can “see” light and we can feel heat. But there are other types of energy that our Sun produces. Much of this energy makes up the electromagnetic spectrum. Light is part of the visible section of the spectrum and heat is part of the infrared section of the spectrum. Radio waves, microwaves, ultraviolet rays, X-rays, and gamma-rays all are parts of the spectrum of electromagnetic energy — or radiation — from the Sun.

Radiation is energy that travels in waves or as particles. Radio waves, microwaves, visible light, and infrared radiation have relatively long wavelengths and low energy. But ultraviolet rays, X-rays, and gamma-rays have shorter wavelengths and higher energy. This shorter wavelength is so small that these wavelengths interact with human skin, and cells, and even parts of cells — for good or for bad!

Our Sun also produces cosmic radiation. Cosmic rays are very high energy, fast-moving particles (protons, electrons, and neutrinos) that can damage DNA, increasing the risk of cancer and causing other health issues. Cosmic rays have such high energy that it is difficult to design shielding that blocks them; cosmic rays do not only come from our Sun, but from other places in our galaxy and universe.

Human Eye Response

The subject of this activity is ultraviolet — UV — radiation. Humans need UV radiation because our skin uses it to manufacture vitamin D, which is vital to maintaining healthy bones. About 10 minutes of Sun each day allows our skin to make the recommended amount of vitamin D. However, too much exposure to UV causes the skin to burn and leads to wrinkled and patchy skin, skin cancer, and cataracts.

On Earth, we are protected by our atmosphere from most UV radiation coming from the Sun. The ozone layer absorbs much of the UV portion of the spectrum (UVB and UVC). Some still gets through (UVA and a bit of UVB). We can protect ourselves completely by covering ourselves with clothing and using sunblock. Our atmosphere protects us from most of the X-, gamma-, and cosmic rays as well.

On Mars there is very little atmosphere to protect living things from UV radiation — or from X-rays and gamma-rays or even more dangerous cosmic rays. Organisms would have to provide their own protection in the form of body changes (adaptations) or sheltered environments (such as underground). These measures would work fairly well for protecting against UV radiation.

The UV-sensitive beads used in this experiment serve as UV radiation detectors. They contain a pigment that changes color when exposed to ultraviolet radiation from the Sun or from UV lights. The intensity of the color corresponds to the intensity of the UV radiation. When shielded from UV sources, or when exposed to light that does not contain UV radiation — such as indoor light bulbs — the beads remain white. The beads are designed for multiple uses and, according to the manufacturers, will change color up to 50,000 times.

Activity - Part 1

1. Have the children describe some characteristics of Mars that might be helpful to life. If you have conducted previous activities, such as Mars by the Book or the Mars from Above activities, remind the children of their discoveries during those activities.

  • Is there an atmosphere? Yes!
  • What is it as thick as the Earth’s? No!
  • What is the surface like? What types of features are there? Volcanos, craters, and stream channels.

2. Discuss the challenges that living things on Mars would face. Recall the group definition for life and its needs (the four requirements) from previous activities.

  • How is Mars different than Earth? Smaller, much colder, drier, thin atmosphere, windy, no liquid water at the surface, etc.

3. Introduce the topic of solar radiation. The children may be unfamiliar with UV radiation and its effect on skin; you may need to lead them through the discussion.

  • What does our Sun give us? Light and heat.
  • What happens when you stay outside in the Sun for too long? You get sunburned!
  • What is the part of the Sun’s energy that causes our skin to burn? Ultraviolet energy or radiation. This energy is invisible to our eyes and we cannot feel it, but it still affects our bodies.
  • What protects us from much of the UV radiation on Earth’s surface? Our atmosphere blocks much of the Sun’s UV light. The ozone layer in our upper atmosphere forms a protective sphere, absorbing much of the UV energy.
  • How do you protect yourself from getting burned by the Sun? You wear clothing, use sunblock, and/or stay under a shelter like the shade of a tree, umbrella, or covered patio.

4. Introduce some types of life on Earth that survive in extreme (especially cold, dry) environments. Look over the NAI Extremophile Trading Cards. Optional:  Have the children read and look over the extremophile features in the Life on Mars? trading card set or the activity pages. Note: It may also be helpful to have books about extremophiles from your library collection available for the children to browse through.

  • Does life exist in cold, dry places on Earth? If so, what kind? Yes! Microbes like bacteria and molds and fungi have been found living in ice sheets on Earth, as well as in the extremely dry and harsh conditions of a desert, such as the Atacama Desert in Chile (located in South America).
  • Does life exist in the cold, dry environment on Mars? If so, what kind? We don’t know! Scientists are sending missions to search for signs of life in these places.
  • Optional:  Have the children “create their own” trading card from the module trading card set template.

5. Invite participants to construct their own “martian” — a Mars creature. Explain that their creatures will include radiation detectors (UV beads) that are made from a special pigment that is very sensitive and turns colors when exposed to the ultraviolet rays. Optional:  Hand out the Explore:  Life on Mars? Trading Cards for inspiration. Optional:  Refer the children to the module scientist pages/features.

6. Construct a martian. Have the children design their own creature with a set number of materials that you provide. Encourage them to share their ideas as they build. Optional:  Have the children draw a picture of their creature in their Extreme-O-File activity pages, or have them “create their own” trading card from the module trading card template.

7. When the children finish, ask them what they observe.

  • What color are your martian’s UV radiation detectors — the UV beads? White or creamy.
  • Are your creature’s radiation detectors picking up any signs of radiation in this building? No.
  • Do you think your martian’s radiation detectors will turn colors if it goes out into the Sun? Why or why not? Answers will vary.
  • Will its radiation detectors turn colors if it goes outside into the shade? Why or why not? Answers will vary.

8. Ask the children to cover their martian’s radiation detectors with their hands, and then take it outside. Have them stand in the shade and uncover their creature.

  • What do you observe happening to the Mars creature’s radiation detectors? The beads become lightly colored, indicating that, even in the shade outside, there is some UV radiation reaching the detectors and our skin.

9. Ask the children to cover their martian with their hands again so that no light reaches it. Keep the creature covered for about 2 minutes while the beads change back to white. Use this opportunity to discuss their observations.

  • What do you think will happen when we take our creatures out into the full sunlight? It will change color. Many possible answers here.

10. Let the children now take their martian into the full Sun.

  • What happens to the beads? The beads become deeply colored, reacting to the intensity of the UV radiation to which they are being exposed.

11. Return indoors and continue the discussion.

  • What happened to your martian’s radiation detectors? They changed colors.
  • Did they change in the shade? Yes — a little.
  • In the Sun? Yes — a lot!
  • Where did they change the most? In the direct sunlight.
  • Was your prediction correct? Answers will vary.
  • What caused your creature’s radiation detectors to change colors? The ultraviolet radiation from the Sun.
  • What happened to the radiation detectors after coming back inside, and what caused it? They changed back to white because they were no longer detecting any radiation. UV radiation does not get through the building.

Facilitator’s Note:  Some children may say light caused them to change, and others may say heat. Remind them of their observations about the beads inside; the beads were white, even though they were in the light of the room. Ask them what happened to their beads when they brought them back inside; the beads changed from a colored state in the Sun back to white in the room light. If it is heat that causes the change, invite the children to hold beads in their fists; the beads do not change color when heated. They can also heat the beads with a hair dryer (carefully!). The cause of the change comes from the Sun; it is from the part of the Sun’s spectrum we do not see or feel directly.

  • What did this experiment tell you about UV radiation and YOU? Just like my martian, I am exposed to UV radiation when I am outside, and if I am exposed to too much, I can change color (i.e., get a sunburn) too!
  • How do we protect ourselves from UV radiation? Answers may include wearing clothing, using sun block, using umbrellas, staying inside.

12. Share with the children that with their martian’s help they have demonstrated the effects of the Sun’s ultraviolet rays on objects (and people!) on Earth. Just like it is important for us to protect ourselves from the harmful UV radiation of the Sun, life on Mars also needs protection! Remember, this is one of the requirements for life!

  • Does Mars have more or less protection from the Sun’s UV radiation than Earth? Does it have more or less of an atmosphere? Mars has less atmosphere — less protection!
  • With less protection, what would this mean for life on the surface of Mars? That it would need a way to protect itself!

Activity - Part 2:  Mars Creature Challenge

1. Recall the concept that Earth’s atmosphere protects us from ultraviolet radiation.

  • Where does UV radiation come from? The Sun and it travels through space.
  • How does it reach Earth? It travels from the Sun to Earth.
  • How do you protect yourself from too much UV radiation? Clothing, sunblock, staying inside.
  • What else naturally protects us from most of the incoming UV radiation? The atmosphere. Just like clouds can block some of the visible light on a rainy day, the outer layer of our atmosphere acts as a filter and filters out much — not all — of the UV radiation.
  • Why might UV radiation be a concern on Mars? Because the atmosphere on Mars is much thinner and doesn’t contain an ozone layer to help absorb the UV radiation like Earth does.
  • Can we change our creature to protect it from the UV radiation on martian surface? Yes, let’s try!

Explain that Earth’s atmosphere protects us from many of the dangerous types of radiation from our Sun — ultraviolet radiation, X-rays, gamma-rays, and very high energy cosmic rays. We know that some ultraviolet radiation still gets through (you observed that during Part 1 of this activity), but we can protect ourselves by covering up, limiting our time in the Sun, and using sunscreen. We are going to take what we’ve learned about Mars to help protect our martians!

2. The Creature Challenge:  Invite the children work together in small groups (of 4–6) to protect their creatures from the harsh UV conditions on Mars. The children may modify their creature itself (changing it to the environment) or create a shelter for protection. Ask them to choose one of these options for the challenge. They should make sure that they are able to look inside or hold up and see their UV beads on their creature for the outdoor testing. Encourage the children to share ideas and plan their modifications among their group. Optional:  They may use the Extreme-O-File: Protecting Life activity page to help as they design and plan. Optional:  Have the children draw a picture of their design in their Extreme-O-File activity pages.

  • What other features does their martian need to protect itself from UV radiation? Have them consider how animals and people on Earth protect themselves from the Sun (clothing, living underground, sunscreen, exoskeletons, etc.).
  • Each group of children should do the following:
    • Test at least two ways to protect their creature in two separate experiments. Each group can divide this between themselves so that half are testing the first experiment and others the second experiment. This will allow both experiments to take place at the same time, saving time required to complete the activity.
    • For each experiment, have them take their Mars creature outside again and test it. Remind the children to cover the Mars creature’s radiation detectors with their hands, and then take it outside for testing.
  • What do you observe happening to the Mars creature’s radiation detectors? Many possible answers here!

3. As a large group, have the children share their creatures and observations.

  • What materials offered the best protection for their creature? The worst? None at all?
  • The Sun’s rays turned the Mars creature colors. Do the Sun’s rays ever turn you colors? Yes!
  • What practical things can, and should, you do to protect yourself from UV rays? Wear protective clothing, use sunscreen, don’t stay out in the Sun for extended periods, and definitely don’t expect the shade to protect you! Overexposure to UV rays causes the skin to burn, sometimes badly (ouch!!). And extreme or excessive burning of the skin can lead to skin cancer.

4. Optional:  Invite the children to consider any other features from which their Mars creatures might need to protect themselves, like the dry and very cold martian environment. They can perform fun tests at home such as having their creature spend the night in a baggie in the freezer, etc.

In Conclusion

Summarize the results of the challenge and what they have learned about ultraviolet radiation on Earth and in space. What helps protect Earth from most of its harmful effects? The atmosphere! How is ultraviolet radiation a challenge to life on Mars and other planets? Recall the requirements for life — particularly protection. What do you think are some ways for living things to protect themselves from UV radiation? What happens to organisms — and children — who receive too much UV radiation?

Facilitator’s Note:  NASA Mission Connection
Radiation Assessment Detector (RAD) for Mars Science Laboratory
This instrument, shown prior to its September 2010 installation onto NASA’s Mars rover Curiosity, will aid future human missions to Mars by providing information about the radiation environment on Mars and on the way to Mars. The results may also help scientists to understand the implications for life there. In November 2012, early results showed a connection between impinging cosmic radiation with weather phenomenon on Mars. For more details, please visit MSL- RAD Science Reports.


Credit:  NASA JPL.


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