THE LOST HYDROPONICS  CHAMBER  LESSON

 

 

“It’s the one on the right.”

 

Background Science Summary:

           

Because the definition of hydroponics is growing plants in liquid nutrient mixtures without soil, application in space is advantageous.  The only soil found in low earth orbit is brought by the spacecraft.  Having Christa perform a hydroponics experiment was attractive because of the simplicity of the apparatus required.  However, there was a unique innovation included in Christa’s lost hydroponics lesson.   It dealt with the misting of one of the plants among the six mung beans in the chambers of the apparatus.   The question was: Would misting  serve equally  well as immersing the plants in the fertilizing nutrient solution?  If so, much less mass need be launched into orbit, saving many dollars based on the cost per pound to place objects in low earth orbit. 

 

 

 

 

Christa Planning Hydroponics Chamber  in Space Demonstration

Click on

hydroponics_ground_practice.wmv (3.0 MB, hi-res wmv file 7.1 MB)

to start the video.

 

In the above video, Christa deals with planning the best location for the hydroponics chamber based on expected lighting conditions in the Orbiter for photography.  Because plant growth might be  affected by available lighting, this was an important consideration.   With only seven days for plant growth during the mission and limited lighting, the six mung beans were given the opportunity to germinate, as well as for three of them to grow for two days prior to launch.

 

 

 Christa, Barbara, and Bob Mayfield practicing the Hydroponics Chamber  Lesson
in NASA’s zero G aircraft. Click  here (1 MB, hi-res wmv file 4.0 MB) to start the video.

 

The photo above is extracted from the Zero G practice session with the hydroponics chamber.  The exercise appears to be dealing with setting up the “misting” procedure, i.e., the spraying of the fertilizing nutrient into chamber six, apart from the remaining five chambers containing liquid fertilizer.  The photo below  is cropped from Christa’s  zero-G exercise with the hydroponics experiment. 

 

 

The Hydroponics Experiment Apparatus

 

 

Editor’s Interpretation Based on Bob Mayfield’s Description

 

Editor’s sketch based on Mayfield’s description of a single

hydroponics chamber

 

Hypothesis:

 

The explanation written by Bob Mayfield is an excellent summary of what Christa might have demonstrated aboard Challenger using  the hydroponics chamber.   The class project which follows replicates the on-orbit experiment with materials readily obtainable from local stores.  After constructing the six chambers, the six mung seeds are treated exactly the same way Bob Mayfield describes them being treated prior to launch and during the one week mission.                                                                                                            

 

By continuing the experiment for a period of seven days, with misting of chamber six once per day, Christa’s lost hydroponics chamber experiment may be  performed in the classroom.  Above is a sketch of the Challenger experiment based on the previous photos and Bob Mayfield’s description.  

 

Because the class experiment is performed in a one-g environment, the apparatus is much simplified from that seen above.  The volume above the emerging plant stems need not be enclosed, i.e., the leaves may simply droop over the edge of each chamber.  Additionally, there need be no lexan ring holding the one half inch mesh of polyester fiber in place. 

 

The proposed experiment, as addressed in Mayfield’s paper, only spoke of the mung bean nutrient as a fertilizer.  No chemical composition was suggested.  However, based on the vigorous growth of the mung bean, water may be employed as long as it has a ph suitable for growth.  Any bottled water from a grocery store should be appropriate.  Even tap water might be used.  The class can experiment with an altered nutrient solution by adding Miracle Grow, sugar, or other additive to the nutrient solution.  Nevertheless, whatever is chosen, it is important to employ the same solution in each chamber as well as the misting liquid sprayed into chamber six.                                                                 

 

The vigorous growth of the mung bean during the pre-gemination stage requires little or no light so that the limited lighting in the space shuttle crew quarters. 

Materials:

 

1. Six clear plastic empty 20 oz. soft drink containers
2. One of the six containers has a hole drilled in the side near the  chamber bottom for atomizer insertion and root misting.
3. Bandage Gauze from Drug Store
4. A pound of mung Beans
5. Atomizer for misting the roots of the chamber six plant once per day
6. Clear  adhesive tape encircling all six containers so that they are inline for viewing, photographing and performance of the experiment
7. Scissors
8. Adhesive labels, one per chamber
9. (Optional) Digital Camera record of daily growing progress.

Procedure:

 

The greatest challenge is constructing the six hydroponics chambers.  Five are identical with the sixth differing in having a hole made in its side near the bottom in order to spray fertilizing nutrient into its  root system once per day. 

 

           

The pictures which follow depict the steps for converting each of the six 20 oz. soft drink bottles into a hydroponics chamber:

 

1.      Empty the bottle of soda/spring water and thoroughly clean it, rinsing it with tap water.

2.      Remove all labels so that the insides can be clearly viewed.

3.      Remove the cap and discard it.

4.      With scissors cut the bottle into two sections as shown. Caution: Have the teacher or an adult do this by first puncturing the bottle at the desired cutting point. Insert the sharper of the two scissor blades into the puncture and begin cutting around the circumference perpendicularly to the bottle’s length.

5.      Rotate the top half of the plastic bottle 180 degrees and  

      insert it into the open mouth of the bottom half.

6.      With adhesive tape, secure and seal the two halves at the seam to keep  the chamber from leaking.  Fill the chamber with water to test the seal.   Add more tape if water leaks from the seam.

7.      Affix an adhesive label, numbering the chambers in order from one to six.  

8.   Repeat the above steps for five additional chambers.

9.  For the sixth chamber, puncture the chamber’s side  approximately a half inch

      from the bottom with the sharper blade of the scissors.  Cut a half inch    

      diameter hole starting at the punctured opening.  (Caution: Have your teacher

      or  an adult cut the hold for spraying nutrient into the root system once per

       day.)   After each daily spraying of the roots, tape closed the access hole with

       clear adhesive tape. 

      10. Tape around the entire collection of six chambers so that they assume a   

             horizontal in line configuration. 

(ABOVE FIGURE: A DEPICTION OF THE PROCESS USED TO CONSTRUCT THE HYDROPONIC LOST LESSON CHAMBERS)

 

Hydroponics Chamber of Six

 

11. Fill the first five bottles with the fertilizing nutrient solution up to the level where the upside down neck flares out.
12. Stuff the gauze into each  bottle forming a layer one half to one inch thick above the neck making certain some of the gauze is wetted by the nutrient solution.
13.  Shake the bottle vertically so that the gauze becomes damp and contacts the liquid.
14. After  two days of germinating three mung beans small sprouts should show.  Place the three plants respectively in the gauze of chambers one, two and three.  (Note: These have  geminated from seedlings such that once a sprout appears the geminated mung beans continue  to be in contact with the solution for forty-eight hours before placing them in the hydroponics chambers.)  Place  three un-geminated, i.e., mung bean seedlings  (that have been in a nutrient solution for three days) in the gauze in the remaining three bottles, nesting each bean into the damp gauze. 
15. Place the hydroponics chamber in the window or outside in the Sun during the day. (Note: the pre-germination of the three mung bean seeds can be accomplished simply by allowing them to begin the experiment three days early giving them an overall nine days in the nutrient solution.)
16. Take a photo of the six in line  chambers with the digital camera.
17.  At the same time each day, take a picture for a period of seven days. 
18. After each day’s picture taking, spray nutrient liberally into chamber 6 so that the mist thoroughly saturates the volume of air beneath the gauze in chamber 6.
19. Measure the length of the plants above the gauze  and determine other characteristics each day.  Finally,  record your findings along with a printed copy of the daily chamber picture.   

What Would Have Happened on Challenger?

 

This question is best answered by actually performing the above experiment.  In the process, ask these questions:

 

1. How would the absence of gravity have affected the apparatus designed for the classroom?
2. What impact would ambient lighting onboard Challenger have compared to classroom lighting?
3. Based on classroom plant growth over seven days, was the hydroponics chamber design adequate to contain the plant volume produced?                                      
4. Do a report on the characteristics of the mung bean.   Why was it a good choice for the Challenger hydroponics demonstration?
5. Would the hydroponics chamber grow plants in the Shuttle’s cargo bay…why or why not?  Discuss.
6. Finally, examine the STS-118 Educator in Space Mission which dealt with the same considerations for building a classroom hydroponics chamber.  What makes it more doable and less complicated than the hydroponics lost lesson proposed for Christa on STS-51L?
7. Compare Christa’s Hydroponics Lost Lesson Chamber with the commercial Plant Growth Chamber carried to the space station for the hydroponics lesson planned for students after STS-118.  How does the commercial chamber [adapted from a ground based chamber for the space station experiment] compare with Christa’s?
8. Compare the STS-118 choice of  basil seeds with STS-51L’s mung beans.   Would basil seeds have worked better or worse  for the Challenger Hydroponics Loss Lesson?   Why or why not?  

FOR TEACHERS ONLY:  An actual in space hydroponics experiment growing mung beans was conducted on STS-3 so that the Challenger Hydroponics Lost Lesson was partially validated earlier.  The class need not know this prior to answering the above questions.  However, the following was reported concerning the STS-3 experiment: In “Mung bean seeds were grown in a plant growth unit on STS-3. After eight days of microgravity, most of the seeds germinated and grew as tall as the 1-g standards; a few plants appeared to become directionally disoriented.  

 

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For added information or copies of the project, contact the project editor Jerry Woodfill, at ER7, NASA JSC, Houston , TX 77058 .  Phone: 281-483-6331,  E-mail: jared.woodfill-1@nasa.gov

 

The project is a work of the Automation, Robotics, and Simulation Division of the NASA Johnson Space Center , Houston , Texas . As part of the Space Educators’ Handbook, its ID identifier  is OMB/NASA Report #S677.