Planets in a Bottle
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Planets in a Bottle "Life on the Edge" enters the classroom
Mar. 16, 1999:
NASA/Marshall's "Life on the Edge" program is barely a month old but
it's already producing results in some grade school classrooms.
"It was wonderful," says Mrs. Nancy Walters, whose 3rd grade class recently tried some simple microbiology experiments with yeast. "The kids felt like they were doing real science, and they couldn't stop talking about it for days."
Life on the Edge is an educational program that aims to expose grade school students to some of the basic principles of astrobiology and to explore the possibilities for life elsewhere in the Solar System. The program began just over a month ago when 50 lb of yeast and other microbes were delivered to a summit in California's White Mountains. Conditions there present severe challenges for most forms of life, so it is a good place to test the response of microbes to extreme environments. Some of the microorganisms will remain there for months, and some for longer than a year before they are retreived and distributed to classrooms for experimentation.
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One of these ideas, called "Planets in a Bottle," was field-tested in a 2nd/3rd grade class room in February.
"'Planets in a Bottle' is a simple way to test the viability of yeast samples, and a great way to teach young students about conditions on other planets," explained Dr. Tony Phillips, who is evaluating the concept in classrooms. "The basic ingredients for a planet in a bottle are 1 cup of warm water, 3 sugar cubes, a 1/4 oz. packet of yeast, a half liter plastic water bottle, and a nine inch party balloon. Simply mix the sugar, water, and yeast in the bottle, and cap the bottle with the balloon. A healthy sample of yeast will inflate the balloon to 12 inch circumference in less than an hour."
What happens is this: In the nutrient broth -- warm water containing both dissolved oxygen and sugar -- yeast metabolizes the sugar and produces carbon dioxide. The rate of carbon dioxide production at any given instant is proportional to the number of healthy microbes in the bottle. Because the yeast are constantly reproducing through cell division the number of microbes increases exponentially. Likewise, carbon dioxide production increases. The balloon inflates slowly at first, then rapidly accelerates.
In practice the balloon inflates to maximum volume in about 45 minutes. That's when the yeast have consumed all the available nutrient. At room temperature the cells remain viable for several hours afterward and then begin to die. The maximum volume of CO2 and the time required to produce the gas can be used to estimate the number of healthy microbes in the original sample.
Click here for a sample "Planets in a Bottle" lesson plan
"Two weeks ago we visited Mrs. Walter's 3rd grade classroom in Bishop, CA" continued Dr. Phillips. "The class was divided into seven groups, each with the basic ingredients for a Planet in a Bottle. Rather than have every group do the same experiment, we added variations so that each bottle would represent a different planet. For example, the Moon has no atmosphere to protect its surface from solar UV radiation. So, one group exposed their yeast to a UV lamp before adding the microbes to the nutrient mix, creating a "Moon in a Bottle." Another group used scalding hot orange juice as a nutrient mix for 'Venus in a Bottle.' Citric acid in the orange juice served as a substitute for sulfuric acid in Venus's hot atmosphere."
Above: Young scientists monitor yeast growth in a bottle labelled "Pluto". In this case the yeast were frozen for weeks before being added to the nutrient mix.
"Clearly we can't reproduce true planetary conditions in a simple water bottle, nor did we pretend to, but these excercises have powerful teaching value. Every kid in Mrs. Walter's class now knows that Venus has acid in its atmosphere thanks to the orange juice experiment, and they also learned that weak acids are not deadly to yeast," Phillips said.
"My students were really excited when their balloons began to inflate," recalled Mrs. Walters, "but the best part came at the end when we measured the sizes of the balloons and held a classroom debate about the results. We argued about which planet was most congenial to yeast and what the limitations of our results were. It felt like real science."
Left: Students in Mrs. Walter's 3rd grade class debate the question: "Which planet is really best for yeast?"
NASA scientists have a crowded schedule of classroom visits planned in the months to come, even though the Life on the Edge yeast container won't be retreived for some time. The goal is to develop safe and effective classroom protocols before the yeast packets are distributed nationally.
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To view a prototype lesson plan for "Planet in a Bottle" yeast experiments click here. Readers are invited to try the experiments (they are lots of fun) and we welcome comments from educators and others to improve our procedures. Please send comments and suggestions to email@example.com.
looking for a few good volunteers|
Next month we'll be inviting educators, students, and other scientists to join us as participants in Life on the Edge. If you have an interest in learning about life in extreme environments, you'll be able to sign up to receive a sample packet of microbes returned from the White Mountain summit. What's it cost? Nothing! We'll simply ask that you try out some of our classroom-safe lab protocols and give us your feedback. If you're interested please sign up for our Partners in Discovery program.
What is Life on the
Edge? Why study life in extreme environments? How do I become
To learn more about yeast click here.
The White Mountain Research Station - from the University of California
The Star Trails Society - join NASA as a partner in Discovery
NASA/Ames Astrobiology Web Site -- something for everyone interested in astrobiology
Sled dogs carry astrobiology to dizzying heights -- Mar. 11, 1999, Siberian huskies carry a 50 lb
container of yeast and other microbes to a 13,000 summit in California's White Mountains.
Life on the Edge -- Jan. 13, 1999, an educational initiative to teach students about life in extreme environments
The frosty plains of Europa -- Dec. 3, 1998, new evidence for water on Jupiter's moon.
Callisto makes a big splash -- Oct. 22, 1998, Scientists may have discovered a salty ocean and some ingredients for life on Jupiter's moon
Great Bugs of Fire -- Sep. 16, 1998, NASA sends volcano-loving microbes into orbit for materials science research.
Earth microbes on the Moon -- Sep. 1, 1998, Three decades after Apollo 12, a remarkable colony of lunar survivors revisited.
Exotic-looking microbes turn up in ancient Antarctic ice -- Mar. 12, 1998, microbes in the ice above Lake Vostok
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|For more information,
Dr. John M. Horack , Director of Science Communications
|Author: Dr. Tony Phillips|
Curator: Linda Porter
NASA Official: Gregory S. Wilson