Learning Objectives

After this activity, students should be able to:

• Explain the difference between skeletal, cardiac and smooth muscle.
• Explain the difference between involuntary and voluntary muscles.
• Describe what happens to astronauts' muscles in outer space.
• Relate that engineers help astronauts stay healthy in outer space by designing special exercise machines.

Materials List

Each group needs:

• Pencils
• Paper
• Crayons
• Books with images of muscle cells and/or muscle cell slides and microscope

Introduction/Motivation

Muscles can be classified in many ways. Can you name a muscle? Well, the heart is a muscle! This muscle is called cardiac muscle.

Skeletal muscles are some of our largest and most powerful muscles, (like our biceps, triceps, and quadriceps), and they are connected to our bones with tendons. Skeletal muscles are the only muscles that are voluntary. Voluntary means the opposite of involuntary. If we think about it, we can do it. Close your eyes again, and tell your arm to move so you are raising your hand. No open your eyes. Did you raise your hand? Yes, you did! That is because skeletal muscles are voluntary muscles!

When astronauts travel into outer space, they live in a microgravity environment, or a place with less gravity than on Earth. Gravity on Earth is what holds on the ground and keeps us from floating away. That is why we see pictures of astronauts floating around in space, because there is little gravity to hold them in place. Since there is almost no gravity in outer space, astronauts' muscles do not work as hard as they do on Earth (i.e., through general, daily movement). This leads to muscle atrophy, which means that the astronauts' muscles get very weak quickly. When muscles get weak, they do not work as well. Muscle atrophy leads to people not being able to lift heavy things or move very easily. Of course, we do not want that to happen to the astronauts who travel in space!

Because of microgravity, regular exercise machines ─ the one that work on Earth ─ do not work in outer space. So, in order to help the astronauts stay healthy, engineers have designed special exercise machines for space travel. In order to effectively design these machines, engineers need to know how muscles work and how microgravity affects them. Today, we are going to learn a little more about different muscles, and consider how we can exercise them. This will help us understand how engineers design machines to help astronauts exercise while in space.

Procedure

Background Information

So that astronauts get adequate exercise while in space, there are three different machines that they use: the RED (Resistive Exercise Device), the CEVIS (Cycle Ergometer with Vibration Isolation System), and the TVIS (Treadmill Vibration Isolation System). This equipment, designed by engineers, allows astronauts to counteract the physical muscle loss due to atrophy (weakening of muscles due to being in a microgravity environment).

The RED allows astronauts to complete weight-training exercises, the CEVIS (see Figure 2) is similar to an exercise bike, and the TVIS (see Figure 3) is a free-floating treadmill.

As shown in Figures 2 and 3, the astronaut has to be strapped down or attached to the machines to prevent him from floating away!

Before the Lesson

The focus for this activity is on skeletal (voluntary) muscle. Visit the library and get books with pictures of muscles and musculoskeletal systems. If possible, get slides of muscles and set up a microscope for students to view the slides.

With the Students

1. Briefly discuss the different types of muscles (cardiac, smooth and skeletal). Talk about voluntary movement (the ability to tell a part of the body ─ our arms and legs ─ to move), vs. involuntary (we cannot control our heart by thinking about it). Discuss how muscles work in teams, just like engineers and astronauts. (For example, the face uses over forty different kinds of muscles to make expressions.)
2. Discuss the problem of muscle atrophy in space (muscles grow weaker in space because, due to microgravity, they do not have to support the weight of the body; in a microgravity environment, the body is almost completely weightless).
3. Discuss the challenges of exercising in microgravity (exercising in space is tough if the body is weightless; for example, lifting weights does not help your muscles get stronger because the weights themselves are nearly weightless. This is why NASA engineers designed special exercise machines for astronauts to use while in space).
4. Show students pictures of actual exercise machines that NASA designed for astronauts to use and discuss how they work in microgravity conditions. (See Figures 2 and 3.)
5. Group the students into teams of 6. Have the students look up different kinds of skeletal muscles from the library books and, if possible, examine slides of muscles under the microscope.
6. Have teams choose one skeletal muscle for which they would like to design a microgravity exercise machine (leg, arm, back, etc.). Ask students to write that muscle down at the top of a sheet of paper.
7. Have each team brainstorm what type of exercise activities might be used to strengthen that muscle (sit ups, push ups, running, walking on your hands, etc.).
8. Have the students design a machine to strengthen that muscle, using at least one of the exercises they came up with (in step 7 above). Have them draw a picture of their machine and write a sentence to explain how it works. Encourage the teams as they design and draw their machine. (Teachers: encourage students to carefully consider and include the modifications needed in a microgravity environment in their designs.)
9. If time permits, have student teams review their design with the entire class. If time is short, ask a just a few student teams to volunteer to show their design to the class.

Vocabulary/Definitions

Atrophy: To waste away or decrease in size.

Cardiac muscle: Involuntary muscles located in the heart.

Involuntary muscle: Muscle that does not respond to thinking about movement.

Skeletal muscle: Voluntary muscles attached to bone.

Smooth muscle: Involuntary muscles located in the hollow internal organs.

Striated muscle: Muscle that appears to be striped – both cardiac and skeletal muscle are striated.

Tendons: Tough tissue that attaches skeletal muscles to the bone.

Voluntary muscle: Muscle that responds when thinking about movement.

Assessment

Pre-Activity Assessment

Brainstorming: As a class, have the students engage in open discussion. Remind students that no idea or suggestion is "silly." All ideas should be respectfully heard. Have the class brainstorm a list of all the things our muscles enable us to do. Write all the ideas down on the board and guide students towards ideas they may not have considered (walk, run, jump, smile, laugh, eat, go to the bathroom, cry, frown, giggle, play hopscotch, swim, ski, snowboard, do ballet, play basketball, pump blood through our body, breath, etc.). Next, talk about voluntary and involuntary muscles, and write an "I" (involuntary) or a "V" (voluntary) next to each action.

Activity Embedded Assessment

Describe It In Words: Have the students write next to their machine which muscle (or muscles) it will exercise. Have the students write two sentences about these muscles (where they are located, voluntary vs. involuntary, cardiac vs. smooth vs. skeletal) on a sheet of paper.

Post-Activity Assessment

Job Interview: Tell the students you are a senior engineer from NASA, and that you are looking for some trained biomedical engineers to prepare exercise machines for the next space shuttle. However, in order to get the job, they must be able to correctly answer the following five questions:

• How many kinds of muscles are there? (Answer: three)
• What are the names of the kinds of muscle? (Answer: smooth, skeletal, cardiac)
• Which ones are voluntary and which are involuntary? (Answer: Skeletal is voluntary; cardiac and smooth are involuntary)
• What happens to astronauts' muscles in outer space? (Answer: They atrophy, or get weaker, because of the microgravity environment.)
• Who helps the astronauts exercise in space and what do they design and build? (Answer: Engineers! They design and build special exercise machines that work in outer space to help the astronauts keep their muscles strong.)

Congratulate the students on passing their job interview and being hired to work for NASA!

Activity Extensions

• Show students pictures of astronauts exercising in outer space. Have them discuss which muscles the individual machines are exercising.
• Talk about how aging on Earth is similar to what the astronauts experience in space. Explain that our muscles atrophy as we get older – just like the astronauts' muscles get weak while in outer space. Ask the students what we need to do to keep our muscles strong on Earth. (Answer: exercise)

Activity Scaling

• For upper grades, have students figure out the weight of their muscles on Earth as a math extension. (Note: 2/5 of the body is made of muscle, so if a person weighs 100lbs, 40lbs of their body weight is muscle.)
• For lower grades, have students draw one of the muscles from the library books and label it.

References

Copyright

Contributors

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Learning Objectives

After this activity, students should be able to:

• Explain the challenges of eating in space (microgravity).
• List the three main steps in the engineering design process (design, build, test).
• Describe some of the devices engineers have designed to help astronauts eat in outer space.
• Work in teams to design and build their own device for eating in outer space.

Materials List

Each group needs:

• scissors
• white glue
• tape (cellophane, masking, etc.)
• pens and pencils
• Design Worksheet, one per team (also available in Spanish) 

To share with the entire class:

• paper
• rulers
• assorted building materials for their prototype devices, such as balsa wood, construction paper, toothpicks, popsicle sticks, white paper, string, aluminum foil, paper clips, styrofoam, foam core, film canisters, etc.
• markers and crayons
• (optional) hot glue gun (for use by the teacher)

Worksheets and Attachments

Introduction/Motivation

What do you think it would be like to try to eat in outer space? Can you imagine trying to eat a snack as it keeps floating away from you? Well, that's what would happen in an environment with little gravity (see Figure 2). It seems like it would be pretty tricky! Astronauts face a lot of new challenges when they travel in space, and one of those challenges is figuring out how to eat. Thankfully, the astronauts have a whole team of engineers and scientists who help get their food ready for them and design ways to help them eat it without it floating away.

Who can guess some of the astronauts' favorite foods to eat in space? See Figure 3 for a list of the top 10 foods they like to take on space shuttle missions.

The engineers who design ways for the astronauts to eat in outer space must design a lot of different items for their use—even the salt and pepper shakers! If salt and pepper got loose in the space station or space shuttle, it could get stuck in equipment and cause a lot of damage. So, the astronauts use salt combined with water, and pepper in oil to season their food. The salt and pepper come in small bottles (see Figure 4) and work perfectly well for the astronauts.

Engineers have designed many ways for astronauts to have food in space. When astronauts first started traveling in outer space, much of their food came in squeeze tubes, similar to toothpaste tubes. As you can imagine, food from a tube would not be that delicious, and the astronauts were not thrilled with this "food in a tube." Another food item that the astronauts used to eat were small bite-sized cubes of food (see Figure 5). These were somewhat better than the squeeze tube food, but still did not taste too great.

To provide astronauts with better-tasting foods, engineers came up with some new ideas for space food! Obviously, engineers have many goals in mind as they design food for the astronauts, but the two most important goals are to conserve space and weight. Because most foods are 90% water, it makes sense to remove the water and add it in later—ultimately saving weight and volume. The NASA engineers also want to minimize the garbage that generated from the meals. And one more goal—they want to make the astronauts' food taste delicious!

Now, seven different forms of food are available to astronauts—giving them more meal choices. Before the astronauts go into space, they pick out exactly what they want to eat from the available food choices. Some selections include: Rice Krispies®, sweet 'n sour chicken, brownies, Cornflakes®, scrambled eggs, strawberries, and macaroni and cheese (see the Baseline Shuttle Food List for more). They have an oven on the space shuttle, but no refrigerator or freezer. So, astronauts can have warm dinners, but no popsicles!

A lot of people work to prepare the astronauts' food for space flight; then, when they take off, all their food is waiting for the astronauts in the space shuttle. Each astronaut has a unique colored dot on all their food packages so they can easily tell which packages belong to them. And, since most of the astronauts' food is sealed up in packages, another important component of their meal tray is scissors—needed to open the packages. Each astronaut has his/her own set of flatware and scissors.

The astronauts' drinks are powdered, and they come in flexible beverage packages with a special adapter, called a septum adapter, into which they add water to re-hydrate the powder. Once the water is added, they put a straw in the same opening.

When engineers, such as the engineers at NASA, want to design something, they go through the engineering design process. Today we are going to become NASA engineers and practice this process. Then you will put the design and building parts into practice. As you will see, a lot of work that goes into eating lunch in outer space!

The Engineering Design Process

The engineering design process is a set of steps that engineers go through when they want to design a solution to a problem. Remember these three main steps of the engineering design process: design, build and test. We are going to talk a little bit about each step, and then you are going to get to try them out yourselves.

Design: Before engineers build anything, they first figure out exactly what they are going to build. They determine out how big it should be, how much it can weigh, what shape it should be, and how much money can be spent building it. Often, they talk to the people who are going to use their design, and they decide what features they want it to have.

Build: Once engineers have finished a design and are happy with it, they build a model or a prototype of it. Models are usually smaller than the actual design, and there are many different types of models—some look just like the design, but in miniature, and others only exist on the computer. A prototype is another version of the design. A prototype generally functions just as the final design will, and it is an opportunity to work out and fix some of the trouble spots that might—and usually do—arise before the final product is built.

Test: Once engineers have a model or prototype ready, they run many different tests on it: strength, waterproof or not, weight, breakability, etc. They run many tests (sometimes over and over again) to ensure that the product can do what they designed it to do. If their device fails a test, or if the engineers discover some sort of problem with it, then they go through the cycle again—they re-design, re-build, and re-test until it is exactly how they want it to be.

Now that you understand the design process, we are going to design and build our own devices to help the astronauts eat in space given constraints on some of the supplies, time (only one class period) and cost (assign a dollar amount to each length of material used and require students stick to a budget). Unfortunately, we will not get to travel into outer space to test our designs, but we can still do a great job on the design and build parts of the process!

Procedure

Background Information

The seven forms of food are: rehydratable, thermostabilized, intermediate moisture, natural form, irradiated, condiments and shelf-stable tortillas.

Rehydratable food is food or beverages that have had the water removed. To prepare, astronauts just add the water back in and heat the food up in an on-board oven. Breakfast cereals can be pre-packaged with dry milk and sugar, and are ready to eat once water is added. These foods might include soups, casseroles and appetizers (see Figure 6).

Thermostabilized food has been heat processed to kill organisms. These packages are heated, opened with scissors and eaten. This type of food is generally packaged in cans, plastic cups or flexible pouches. Food choices include beef tips with mushrooms, tomatoes and eggplant, and ham.

Intermediate moisture foods have just the right amount of water in them: not too wet (to prevent microbes from growing in the package) and not too dry (to help cut down on the amount of preparation for the astronauts). Essentially, these foods are ready-to-eat right out of the package. Examples are dried peaches, pears and apricots, and dried beef (see Figure 7).

Natural form foods are ready-to-eat. They come in clear, flexible pouches that are cut open with scissors, and they include granola bars, nuts and cookies (see Figure 8).

Irradiated foods are meat products that also come in flexible, foil-laminated pouches, and have been sterilized by radiation. There are 12 kinds of irradiated meat products, including: beefsteak, sliced turkey, breakfast sausage and fajitas. The FDA only permits a few foods for the general public to be irradiated (at very low levels), so NASA has special permission to irradiate meat at higher levels so that the meats do not need to be refrigerated. (Note: meats that the general public eats that have been irradiated at the standard, low levels still need to be refrigerated.) As we have learned, with no refrigerators on the space shuttle, irradiation at higher levels is important.

Condiments include ketchup, mustard, mayonnaise, hot sauce, salt and pepper (see Figure 4).

Since bread is bad news on the space shuttle—because the crumbs can get into the machines and affect their functioning—shelf stable tortillas are used instead. NASA developed special packaging for these tortillas, so they will not mold. Pretty nifty stuff!

Before the Activity

• Gather materials and make copies of the Design Worksheet, one per team.
• (optional) Make copies of the Baseline Shuttle Food List to hand out during the Introduction/Motivation presentation to the class.

With the Students

1. Review with students the seven forms of food (see the Background section). Explain that these forms of foods help with the problem of eating in microgravity and demonstrate some of the solutions NASA engineers have developed for food during space flight. Tell students that today they will act like NASA engineers and design a form of food or device to help the astronauts eat in space.
2. Write the three main steps of the engineering design process on the board: design, build and test. (Note: See the Introduction section for more on the engineering design process.)
3. Divide the class into teams of 2-3 students each and hand out the worksheets, one per team.
4. Give teams 8-10 minutes to work on their designs and complete the worksheets. Encourage students to focus on a particular food or a specific challenge of eating in space. (Note: This is an open-ended design, so encourage creativity.) Teams may not begin building until their worksheets have been checked off.
5. Once a team's worksheet is checked off, encourage students to begin building a model of their design.
6. To incorporate some mathematics, establish constraints on some of the supplies and have students measure out a certain amount. For example: "you are limited to use no more than 0.4 meters of masking tape, and 2.3 meters of string." Have students work together to measure the permitted amounts. Other possible constraints include time (only one class period) and cost (assign a dollar amount to each length of material used and require students stick to a budget).
7. Give teams some time before the end of class to present their ideas and designs to their peers. Discuss how well each meets the criteria and constraints of the problem.
8. Remind groups to clean up.

Vocabulary/Definitions

engineering design process: A multi-step process by which engineers design a solution to a problem; the basic steps are: design, build and test.

microgravity: A condition in space in which only very small gravitational forces are experienced.

prototype: An early full-scale (and usually working) version of a new design.

septum adapter: A special adapter that enables astronauts to add water to powered, flexible beverage packages.

Assessment

Pre-Activity Assessment

Discussion Question: Solicit, integrate and summarize student responses to the following questions:

• Have you ever seen a picture or a movie of astronauts eating in outer space? It looks pretty funny, right? Why do you think it is so hard for astronauts to eat in outer space? (Write student responses on the board; possible answers include: they are homesick, the shuttle is spinning, they do not have a refrigerator, they do not have an oven, there is hardly any gravity, their food is floating around...)

Lists: With the students, come up with a list of foods that would be easy and foods that would be hard for astronauts to eat in space. (Make two lists on the board. Hard foods might include: spaghetti, cereal with milk, salad, etc. Easy foods might be: tortillas, lollipops, M&Ms.)

Activity Embedded Assessment

Student Interviews: As students are working in groups on their designs, visit each team and ask what they are learning about engineers as they build. (Possible answers: engineers are creative, engineers help people, engineers work in teams, engineers help astronauts, engineers have a design process, etc.).

Post-Activity Assessment

Calculations: Have students determine the total cost of their designs (i.e., multiply unit costs and add).

NASA Engineering Team Presentations: Have students to choose one team member to present their team's idea to the rest of the class or have both/all team members present together. Presentations should explain the problem their team is trying to solve, why they chose a particular design, and any challenges they faced in the engineering design process.

Making Sense: Have students reflect about the science phenomena they explored and/or the science and engineering skills they used by completing the Making Sense Assessment.

Safety Issues

• Remind students to use caution while using scissors.
• Use caution with the hot glue gun. To help prevent accidents, set up a "hot gluing station," that can easily be monitored. Lay down newspaper to catch spills.

Troubleshooting Tips

Encourage students to work as a team – to listen to their teammates and not discourage or make fun of others' ideas.

Activity Extensions

Have students create their own outer-space salt and pepper shakers using small plastic dropper bottles, salt, pepper, oil and water. Tips: Dissolve the salt in water, and suspend the pepper in oil.

Activity Scaling

• For upper grades, encourage students to make their designs to scale. Discuss the numerous iterations that a design goes through before finally being produced and used by the astronauts.
• For lower grades, discuss the importance of teamwork, and explain how engineers and scientists work together in teams at NASA.

References

Copyright

Contributors

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under grants from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation (GK-12 grant no. 0338326). However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.