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Martian Air Breathing Mice
By Denise Murphy
Meet the Mousetronauts

Test the Flow Rate
Members of the Caves of Mars team check the flow rate for the Martian Air Breathing mice, Sally and Roberta. (l-r: Denise Murphy, Tom Meyers and Steve Welch)
For any future missions to Mars, a simple and effective way for the explorers to survive would be to use the Martian atmosphere and turn it into usable, breathable air. Thanks to modern technology, the atmosphere of Mars can be compressed and adjusted to form a breathable mixture for humans. We've been experimenting with mice and crickets in sealed environments while pumping through a breathing mixture of 40% argon, 40% nitrogen and 20% oxygen. The purpose of these experiments is to see whether or not humans can survive unaffected when breathing such mixtures. However, this breathable mixture of gases differs from that of Earth, or any other used in Space missions.

The Martian atmosphere is composed of approximately 95% carbon dioxide, 2.6% nitrogen 1.6 % argon and other trace gases. Earth's atmosphere has approximately 78% nitrogen, 21% oxygen, a small amount of carbon dioxide and many other trace gases. Ideally, breathing mixtures for humans are made up of oxygen to breathe and live, plus a buffer gas, like nitrogen; similar to the real mix of gases we breathe from the Earth's atmosphere. When altering the Martian air, the argon and nitrogen in the atmosphere are difficult and expensive to separate. The easiest and most efficient mixture to form will therefore consist of argon, nitrogen and oxygen. However, the effects that breathing gaseous argon has on living things is not known. A simple experiment was designed to monitor the activities of different animals while breathing a gas mixture similar to that would be convenient for future missions to Mars.

The first experiment performed was on two female house crickets (Nancy and Darlene). Both crickets were placed in a clear, colorless sealed controlled-environment jar with food, water, and vegetation to climb on and hide under. The breathing mixture (40% Ar, 40% N2 and 20% O2) was then pumped through at approximately 800 millibars. The experiment lasted for approximately four days and was terminated because a refill of water was needed. The crickets survived and showed normal behavior throughout. They continue to be monitored in regular atmosphere and have survived (at this writing) for 4 weeks post-experiment in good condition.

Test the Flow Rate
Control Mousetronaut Argo hams it up for the camera.
The second experiment conducted was on two female mice (Sally and Roberta). The mice were set up in a clear, sealed mouse cage (courtesy of Animal Care Systems Inc.), complete with food water and bedding. The breathing mixture flowed through at a pressure of approximately 800 millibars. Both mice survived seemingly unaffected. Unfortunately, too much grease was administered as a seal around the lid of the cage and began dripping down the walls. The experiment was stopped to clean away the grease and lower the amount of mouse bedding inside upon the recommendation of the veterinarian on staff with Animal Care Systems, Inc.

After the grease was cleaned away and the bedding was decreased, Sally and Roberta were put back into the experimental cage and the third experiment began. The breathing mixture flowed through at approximately 800 millibars and their activities were monitored. This third experiment ended successfully on 14 September, 2002 after completing 15 days of continuous exposure to the gas mix. Both mice, now reunited with their control partners, seem unaffected and go about their usual highly active lifestyle.

Although the two completed experiments were short lived, they served their purpose in demonstrating that there are no immediate short term adverse affects that breathing a mixture of 40% argon, 40% nitrogen and 20% oxygen has on crickets and mice. The long term effects are still unknown and the mixture has yet to be tested on humans.

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The Caves of Mars Project is funded by a NIAC Phase II Grant from the NASA Institute for Advanced Concepts.
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