Introduction:

This Legacy Cycle was designed by members of the MIT Mars Society to teach students about the scientific method and some of the issues behind plant growth at a Martian base.  The cycle, as seen on the next page, steps learners through the entire process, from challenge to execution, and utilizes a capstone project of growing plants under experimental conditions to motivate discussion of the issues.

The module was originally taught using Mars analog soil from the NASA Ames Research Center in California.  This volcanic soil is gathered in Hawaii for research use because of its similarities to actual surface regolith on the Red Planet.  However, it may be more difficult to obtain for regular classroom use.  (Don’t let that stop you from trying!  The Ames education office can be reached on the web at http://www.arc.nasa.gov/edu.html :)  Even without the special soil, however, this experiment still provides a valuable look at the whole process of inquiry.  In fact, by carrying out some analysis on soil that is readily available, students could answer many of the questions facing NASA investigators about how to properly determine resources to match the situation at hand.

Additionally, depending on available computing resources and time constraints, some classes may find it simpler to provide information to the students rather than having them do their own web searches.  I’ve included a “Research and Revise II” supplement to help with that.

Ad Astra,
Erika Brown
MIT Mars Society &
NSF VaNTH ERC
Student Outreach
elb@mit.edu

The Challenge: You're getting ready to head to Mars and will be growing all sorts of plants in your inflatable greenhouse once you get there. What will you take with you?

Generate Ideas: What do you think are the important characteristics of plants you would want to grow? What plants have these characteristics? What do you need to take to grow them?

Multiple Perspectives: There are many different priorities to consider. Edible plants provide a healthy nutritional supplement. Plants that produce high volumes of oxygen and other greenhouse gases are helpful for life support and eventual terraforming. And otherplants are very helpful in the production of things on the Martian surface, such as bamboo for furniture or cotton for cloth.

Research & Revise: Utilize handouts and web resources to research previous Mars analog gardening experiments, plant characteristics, and resources needed for growing. Discuss issues that drive choices of what to take. Utilize the scientific method to develop a hypothesis and experimental design for evaluating the chosen plants.

Test Your Mettle: Set up growth experiment; test and evaluate relevant parameters. Did the experiment succeed? How do you know? Did you choose well?

Go Public: Create a summary of your scientific method, including your hypothesis and the logic behind it, how you tested it, what you found, and what you would do differently next time.

The Challenge

Every astronaut preparing for a mission has to learn a number of useful skills to help keep things going smoothly.  Your crew is heading to Mars, and one of the most important areas to specialize in is gardening.  You have a six-month journey ahead of you, but when you land, it’ll be time to fill up your inflatable greenhouse with all sorts of plants!  Out of the millions of plants, what do you want to grow?   And what are you going to take with you to turn this idea into a reality on the Red Planet? And thinking longer term, what about colonizing Mars? You need to decide what plants you would use and what resources would you need.

Generate Ideas

Answer the following questions, and remember, there’s no such this as a wrong answer!  These are just your initial opinions.

• What are all the different things plants can be used for?
• What do you think are the most important characteristics of plants you would want to grow on Mars? 
• What plants might have these characteristics? 
• What do you think you will need to take to grow them?

What is science?

Steps to Experimental Science
(adapted from:  http://www.isd77.k12.mn.us/resources/cf/SciProjInter.html )

1.   Initial Observation – what is the question you want to answer?
2. Information Gathering – what do you already know?  what do you need to find out?
3. Identify Variables – what types of things will affect your system if they change?
4. Make Hypothesis – what do you think will happen if you change one variable?
5. Decide on Questions – what must be answered about your variables?
6. Design Experiments – how are you going to answer your questions? 
   
   • Select only one variable to change in each experiment.    
   • Change something that will help you answer your questions.
   • The procedure must tell how you will change this one thing.
   • The procedure must explain how you will measure the amount of change.
   • Have a "control" for comparison so that you can see what the change actually did.
7. Obtain Materials – what exactly is needed to run your experiment?
8. Do the Experiments and Record Data – do you have the info to answer your question?
9. Record Your Observations – what EXACTLY did you do?  what did you notice?  
10. Perform Calculations as Needed
11. Summarize Results – what exactly did you find out?  can you show it in a graph?
12. Draw Conclusions – was your hypothesis correct?  if not, why?  how do these results affect other questions? 
13. Revise Hypothesis & Experiment – how does your data affect what you would ask and how you would answer it?  can you revise the experiment to answer your new questions?
    

Multiple Perspectives

There are many different priorities to consider when choosing the best plants for the job on Mars.  Below are three different expert perspectives on some of the factors you might consider in choosing what belongs in your garden.

Breath of Fresh Air
Plants are best known for their conversion of carbon dioxide (CO₂) to oxygen (O₂) ). Carbon dioxide is very toxic to humans when at high concentrations - makes the blood basic (opposite of acidic). And oxygen is what we need in breathing - the lungs pass the oxygen into the blood that carries it around, allowing for different organs to use it as a type of energy source. Humans breathe out carbon dioxide. Plants are a great idea to have in a closed system, since they help in converting the carbon dioxide into oxygen.

Another important use of the oxygen that plants create is in the process of terraforming Mars - making Mars more hospitable to life. To allow animals to walk on the surface, plants must convert the CO₂) atmosphere into O₂) .

From the Gardne to the Table
Every day humans need to eat 6 - 8 servings of vegetables and fruits. Edible plants are important since they provide the minerals and vitamins that humans need in order to keep their tissues and organs functioning and healthy. Plants are special since they are able to themselves produce vitamins and uptake vitamins, while humans can't produce these and must eat foods that contain vitamins and minerals. While we can get minerals and vitamins by taking tablets, this is not as beneficent for two reasons. Firstly, due to the other compounds present in plants, vitamins and minerals are absorbed more efficiently when a plant is eaten. Secondly, eating fresh vegetables and plants has a great positive psychological effect on humans.

Workhorse Plants
On the Earth we encounter plant products everywhere! Just look at the desk that you are seating at, or the pencil that you're writing with. Much in human culture is based on using plants for building materials for structures that we use in our everyday life.

For longer duration Mars missions, plants may be a useful source for building materials. While the Martian regolith (soil) contains many elements which are great for building structures, wood from plants is often the best choice. For example, an incentive for growing bamboo may be its strong, but very lightweight structure. Making structures out of wood will also make the people colonizing Mars feel more at home and will have a positive psychological effect.

Research & Revise
In order to start the project, you need to do some background research. You will need to learn more about plants, the conditions under which they grow, and why they would be needed on Mars. This research also lets you find out what has already been done, and what questions still remain. Use the Internet resources below to research previous Mars gardening experiments, plant characteristics, and resources needed for growing your garden.  Then pick ONE plant to grow experimentally and decide what information you want to look at to judge how well your plant is doing.

Some Questions to Think About:

• What issues do you need to consider in choosing a plant for Mars?
• What types of plants have been grown before?  Why were they chosen?
• Do you need anything besides soil and water to grow your plant?
• Do you want to bring soil from Earth or use what is available on Mars?
• What are the things you want to measure about your plant?

Finding Information
(or getting the most out of the Internet)

You are likely to need more information than is available on the sites included on your worksheets.  So how can you do a good search?  It's actually quite easy if you know where to start!

First, start at http://www.google.com or http://www.altavista.com  - these are probably the best search engines today.  For example, if you want to find out information of the history of water on Mars in the past, you could type in:  water Mars past history Google will then search for these words on the web, and will come up with all sorts of sites that have to do with these topics.

If you want for the order of words to matter, use quotation marks around the words that you want together.For example, if you want to find articles by or on Prof. Maria Zuber (she is at MIT and does a lot of Mars Polar research), then you would type: "Maria Zuber"

This makes Google look for the words appearing in exactly that order, rather than a Maria and a Zuber in the same page, and not necessarily together. If you choose Altavista, the idea is the same, but the rules are a little bit different.If the word or phrase must appear in the pages that come up, use a "+" (plus). If you want to make sure that a word does not appear in the pages, use a "-" (minus). So for example:
+Mars +human +mission -robotic
will search for human, but not robotic, missions to Mars.

Most importantly though, BE SMART!   You can spend your entire life looking for information about Mars on the Internet – there’s that much there!  So think about what questions you want to answer most and hunt for those.  Then, when you’ve found a good site, read it or print it out (if it’s not huge) and use that information.

What types of plants have been grown before?  Why were they chosen?

• Mushrooms – need no light, can grow on waste of other plants, produces some protein, but makes little oxygen and has little vitamins/minerals
• Fruit Trees – fruit is high in vitamins, provides wood, but takes up a lot of space and doesn’t grow very quickly
• Bamboo – produces strong, light-weight construction materials, compact groves
• Corn & Wheat – easily grown, good food source, can grow much in a small space
• Soybeans – good source of protein, easy to grow
• Lettuce – almost completely edible, easy to grow, but low in nutrients

What nutrients are in Mars soil? 

Element	Earth average	Mars average
Nitrogen (N)	0.14%	Unknown
Phosphorus (P)	0.06%	0.30%
Potassium (K)	0.83%	0.08%
Calcium (Ca)	1.37%	4.10%
Magnesium (Mg)	0.50%	3.60%
Sulfur (S)	0.07%	2.90%
Iron (Fe)	3.80%	15.00%

Do you need anything besides soil and water to grow your plant?

• A pot – bring a small, clean yogurt container to class!
• Light – the Martian surface only gets 43% of the sunlight that we get here on Earth
• Fertilizer?  On a fertilizer bag, you will find three or four numbers with hyphens separating them. The numbers indicate, in order, the percentage of nitrogen (N), phosphorus (P), potassium or potash (K), and sulfur (S).

What are the things you want to measure about your plant?
Height?  Mass?  Edible Mass?  Useable Mass?  Mass/Area?  Color?  Taste? 

So what do you want to learn about growing plants on Mars???

1. What variable are you going to test in your experimental plant?
2. How are you going to test it?
3. What should be your control?  (What are you going to compare your plant to?)
4. What variables should be held constant between your experimental plant and your control?
5. How are you going to make sure they stay the same?
6. What materials do you need to grow your plants and test your hypothesis?  (Do you want seeds or small plants?  How much light will your plants need?  Do you need to add anything to the Mars analog soil?  etc...)

Next week, set up your experiment.  We’ll take data for 6 weeks as the plants grow, then you’ll evaluate your results. (Did the experiment succeed?  How do you know?  Did you choose your plant well?)

Go Public

In order to make a difference in the world, science needs to be shared.  Create a summary of your scientific method to share with the class and the public.

Things to include:

Background

• What kind of plant did you grow?
• Why did you pick this plant?
• What variable did you test?
• Why did you pick this variable?
• What was your hypothesis?

• How did you grow your plant?
• How did you measure the variables you were testing?

• What did your data tell you?
• Was it what you expected?
• Why or why not?

Conclusions