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Having astronauts living and working on the Moon or a planet such as Mars is a compelling idea. It would provide a new base for space exploration, and could help answer many questions that trouble Earth-based scientists today, such as, “Is there (or has there ever been) water or life outside of Earth?” To survive for an extended time on such stark surfaces, astronauts would need a safe and secure habitat, one able to withstand the different atmospheres, wide-ranging temperatures, high-level radiation, and space debris that characterize these environments.

Humans evolved in an atmosphere—a blanket of gases that gravity holds in place around Earth. The weight of that blanket is called air pressure. The human body has adapted to life in our atmosphere by maintaining an internal pressure pushing outward that balances air pressure pushing in (measured as one atmosphere at sea level). With sufficient oxygen to breathe, we can exist comfortably in pressures down to one-third of an atmosphere. However, at pressures lower than this, gases start to boil and bubble out of the body's cells and tissues, starving the body of oxygen. For all practical purposes, the moon has no atmosphere, and while Mars has an atmosphere, it is extremely thin. For astronauts to live outside of Earth's atmosphere, a structure would need to support an artificial atmosphere.

A Moon or Mars habitat would also need to shield astronauts from harsh temperatures and radiation. Because there is practically no atmosphere on the Moon to help moderate surface temperature, it ranges from extremely hot during daylight—up to 253°F (123°C)—to extremely cold at night—down to -387°F (-233°C). Mars, which is farther from the Sun than Earth, can warm to about 70°F (20°C) during a summer day, but it can drop to -225°F (-153°C) in winter. These landscapes are also directly exposed to the Sun’s cosmic rays and solar wind as well as radiation from other stars. Finally, space is full of small rocks and other debris; most zoom faster than speeding bullets and often will strike the surfaces of the Moon and Mars. These micrometeoroids represent a real threat to any structure and its inhabitants.

NASA is testing a design for a two-layer inflatable habitat that would address each of these challenges. The habitat features lightweight and flexible materials with durable and protective properties. The inner layer, or bladder, is coated in a rubberlike plastic polymer. When the structure is inflated, this layer is forced against the outer layer and becomes part of a matrix that seals in air and creates the artificial atmosphere humans need. To protect against external hazards, especially temperature and micrometeoroids, the outer layer is made of a weave that includes Kevlar, a textile composite often used in bulletproof vests, and Vectran, which is used like webbing to reinforce ropes, cables, and sailcloth. NASA has yet to determine how best to shield its inflatable habitat from radiation. Ideas include creating a “force field” around the habitat. This powerful electric field would have the same charge as the incoming radiation and thus repel it.

Before the Video

• What do you think astronauts would need to live on the Moon or on Mars for an extended period of time? Compose a list of hazards they would need to protect themselves from and a list of items they could bring for protection.
• How do you think astronauts would transport those supplies? How might they "economize," or not transport too much?

After the Video

• How are inflatable structures superior to rigid structures?
• Which parts of an inflatable structure keep the habitat safe for humans and their technologies?

Teaching Tips for Grades 6-8

NGSS Correlations:

Performance Expectations: MS-ETS1-1
Disciplinary Core Ideas:
     ETS1.A:  Defining and Delimiting Engineering Problems

• Criteria and constraints include satisfying any requirements set by society, such as taking issues of risk mitigation into account, and they should be quantified to the extent possible and stated in such a way that one can tell if a given design meets them.

Engineering Practices: Defining Problems

Important components of engineering design include a well-defined problem and a list of constraints that needs to be satisfied in order to determine if a solution is successful. This video is about inflatable habitats that can potentially be used on the moon or Mars. It puts forth some important criteria to ponder and introduces one of the models currently under consideration by NASA.

Before watching the video: Tell the students that -- as useful and interesting as exploration of the Moon and Mars are -- if humans are going to be part of it, we will need to provide a place for them to live while they are there. The module that brings them to the faraway planet or moon is not large enough for them to live in, so another type of structure must be created. You have just defined the problem for them. What criteria should be considered in the design of the structure? Have the students work in teams to create a list of all the things they think should be considered as part of the criteria. The teams should then share these lists with one another, allowing the class to create a final list to use while watching the video. Criteria should be quantified to the extent possible and stated in such a way that one can tell if a given design meets them.

While watching the video: Encourage the students to jot down notes or thoughts about any additional criteria that occurs to them.

After watching the video: Have students work in their teams and write down the problem, as well as the criteria for constraints on the solution. Once that is complete, have a class discussion that compares the criteria list from before the video with the new lists. If all of these criteria are met, will the structure be suitable for humans to live in? Students recognize and identify the problem and its constraints for this problem, part of the Engineering Practice, Defining Problems. 


Teaching Tips for Grades 9-12

NGSS Correlations:

Performance Expectations: HS-ETS1-1; HS-ETS1-3
Disciplinary Core Ideas:
     ETS1.A:  Defining and Delimiting Engineering Problems

• Criteria and constraints include satisfying any requirements set by society, such as taking issues of risk mitigation into account, and they should be quantified to the extent possible and stated in such a way that one can tell if a given design meets them.

     ETS1.B: Developing Possible Solutions

• When engineers evaluate, they must take into account a range of constraints, including cost, safety, reliability, and aesthetics, and to consider social, cultural, and environmental impacts.

Engineering Practices: Defining Problems, Designing Solutions

Important components of engineering design include a well-defined problem and a list of constraints that needs to be satisfied in order to determine if a solution is successful. This video is about inflatable habitats that can potentially be used on the moon or Mars. It puts forth some important criteria to ponder and introduces one of the models currently under consideration by NASA.

Before watching the video: Tell the students that -- as useful and interesting as exploration of the Moon and Mars are -- if humans are going to be part of it, we will need to provide a place for them to live while they are there. The module that brings them to the faraway planet or moon is not large enough for them to live in, so another type of structure must be created. You have just defined the problem for them. What criteria should be considered in the design of the structure? Have the students work in teams to create a list of all the things they think should be considered as part of the criteria. The teams should then share these lists with one another, allowing the class to create a final list to use while watching the video. Criteria should be quantified to the extent possible and stated in such a way that one can tell if a given design meets them.

While watching the video: Encourage the students to jot down notes or thoughts about any additional criteria that occurs to them.

After watching the video: Have students work in their teams and write down the problem, as well as the criteria for constraints on the solution. Once teams have completed the activity, have a class discussion that compares the criteria list from before the video with the new lists. If all of these criteria are met, will the structure be suitable for humans to live in? Students recognize and identify the problem and its constraints for a complex real-world problem, part of the Engineering Practice, Defining Problems. Have the student teams prioritize the items on the new list of constraints. Are some more important than others? Are there any tradeoffs that need to be considered? As a class, compare the prioritized lists. Discuss the similarities and differences in the priorities. Students recognize that the creation of the model is based on prioritized criteria and tradeoffs, part of the Engineering Practice, Designing Solutions.