Building a space habitat in the classroom

Planet Earth is able to meet the basic living requirements for trillions of organisms, including humans. The oxygen we need is in the air around us, the atmosphere protects us from radiation, drinking water can be found in rivers and lakes, and food can be readily found in most places.

On Earth, cycles exist where one species’ waste products are used by another species, so that the waste products do not build up to high levels: an example of this is the complex carbon cycle^w1 in which oxygen and carbon dioxide are alternately produced and used by plant species and animal species.

However, in space, none of these requirements for human survival are met. Therefore, to live and work in space, we have to take with us everything we need, and we need to devise ways to recycle or dispose of the waste we produce. We must do this while limiting the weight of material taken to space and building in backup safety equipment (redundancy).

Weight must be minimised as transport into space is extremely expensive. It currently costs about 17 000 USD to lift 1 kg to the International Space Station (ISS) (based on an average launch cost of 450 million USD and shuttles carrying an average of 26 000 kg of cargo plus astronauts). It will cost much more to take 1 kg to the Moon or to Mars.

At such a great expense and with the inherent difficulty of each mission to space, every kilogram needs to be justified. Furthermore, backup equipment is required for every life-support system in space. Currently, on the ISS, there are three levels of this redundancy, just in case the primary system fails and a backup system is needed.

Getting your students thinking about habitat design on the Moon or Mars can be a good way to consider the challenges of living and working in space as well as illustrating the critical role that the cycles on Earth play in the survival of all organisms. It is an activity suitable for students of all ages (see the suggestions for different age groups, below).

The introduction to the activity will take about 2 hours, with at least a further 2 hours to design the habitat, depending on its complexity. To build the habitat could take 5-15 hours, depending on how many students are involved and how complex a habitat they are building. If the students are really enthusiastic about the idea, they might want to invest even more time.

When you have finished, send a photo of your completed space habitat to editor@scienceinschool.org and we will publish a selection of the photos on the Science in School website.

Designing a space habitat

Begin by asking your students to consider what humans need to stay alive and work efficiently on Earth. How could we meet these needs in space? And how can we build space facilities with the highest efficiency, lightest weight and longest durability? See the box below for many ideas, together with links to more resources, including many from the European Space Agency^w2. Further background information can be downloaded as a PDF or Word^® document^w3.

Now the students can begin to design and even build their own space habitat. First, they will need to decide whether to build their habitat on Mars or the Moon, because the design requirements will differ^w4.

They should bear in mind that the Moon has greater temperature changes and no atmosphere for protection but is closer to Earth. Mars has more moderate temperature changes and an atmosphere, but it is much further away from Earth, thus a Mars habitat will need to be much more independent.

Activity for students aged 7-10

1. Begin by discussing what humans need to survive on Earth and then extrapolate the list to what humans need in space. What is essential for survival in space and what can be removed to save weight and money?
   

   
   
   

2. Discuss how the requirements are important during the design and construction process. Pick two of the requirements that a habitat needs to provide (listed in the box below) and include them in the design of a planetary habitat for at least two people.
3. Build a model habitat out of cardboard and strong sticky tape. The habitat can be room-sized or tabletop-sized. You may find the Worldflower Garden Dome^w5 and Geo-Dome^w6 websites helpful for your design. Decorate the habitat to make it a liveable place, for example by adding colour or windows.
4. Discuss with the group what each student would take with them if they could only choose one personal item (e.g. a family photo, music recording or book).

Activity for students aged 10-14

1. As for the previous group, but pick four to six of the requirements of a space habitat (see box) and include them in a design for at least four people.
2. Give more consideration to the weight of the habitat and the associated costs.

Activity for students aged 14-19

1. As for the first group, but instead of building a cardboard model, small groups of students should use computer modelling software^w7 to create their vision of a habitat. Take into consideration at least eight of the requirements for a space habitat (see box below) for four people.
2. Include a description of the different technologies needed for the habitat, e.g. an electrolyser to produce oxygen from water, or a Sabatier reactor to split carbon dioxide into methane and water^w8, technology that is being tested on the ISS^w9.
3. In the design, incorporate features to support a sense of well-being such as windows, paint colour or leisure areas.
4. Compare what the teams did and see if everyone likes the designs. There will probably be differences in what individuals consider appealing. Discuss how to design one habitat for many cultures.

Acknowledgement

The author would like to thank Scott Hovland from the European Space Agency for valuable comments and advice.