Webcast Kicks Off Global Water Experiment
More than a billion people have no access to clean drinking water, one of the most important components of sustaining human life. NASA is helping students and teachers around the country explore the properties of water and the role it plays in everyday life as part of the International Year of Chemistry 2011.
On Sept. 22, 2011, during a webcast viewed in classrooms from Florida to California and Texas to Illinois, a group of NASA scientists, engineers and educators teamed up with the American Chemistry Society to show how water filtration works on Earth and in space. The experiment, watched by more than 1,500 individuals, was part of the Global Water Experiment, a bigger, four-part investigation that may become the largest chemistry experiment ever conducted.
"When you think about clean water, it's a world issue. Basic clean drinking water is one of the most important resources for human health and survival," said Matt Keil, lead education specialist for NASA's Teaching From Space Office at Johnson Space Center in Houston. "As important as it is, water quality varies greatly from community to community for a wide variety of reasons including landscape, weather, temperature and even human impacts."
To demonstrate how water filtration works on Earth, the team started with about a half-liter of murky, dirty liquid from a local waterway -- they even gave it a few sniffs to verify that it was filled with germs and other sediments not suitable for drinking. First, they poured the water back and forth between two containers to allow any trapped gases out and oxygen in. Then, they added alum powder, which can be purchased at a grocery store, to make the dirt specks stick to each other and form larger particles that sink to the bottom with the help of gravity’s downward pull.
After letting the liquid sit for several minutes, the team made a filter out of common household goods and a few items purchased at a pet store. Students around the country could do this at home. A coffee filter was rubber-banded around the neck of an empty two-liter plastic soda bottle that had the bottom cut off. The bottom end of the bottle was then partially filled with gravel and a level of sand. Together with the coffee filter, the gravel and sand served as a three-layer mechanism that could catch many of the particles that make the water dirty when it's poured through the filter. As the team poured the water into the filter, it trickled through the sand, gravel and coffee filter. It came out the other side noticeably clearer. As a final step, scientists and educators disinfected the water by adding two drops of bleach at a time to the filtered liquid and tested the pH of the water to determine when the chlorine in the bleach had neutralized the germs.
"The activities cover important topics in science and also provide a variety of opportunities to learn experimental data gathering skills," said Valerie Moore, a representative from the American Chemical Society.
"Students worldwide can participate in this and become part of the largest student experiment ever," said Keil.
Scientists and engineers who work in the International Space Station Program also talked about how water is filtered on board the orbiting laboratory. NASA has developed advanced water filtration and purification systems.
"Since it's not practical and (it's) very expensive to get water up to the International Space Station, we've had our engineers design an innovative water recycling system," said Camille Alleyne, assistant program scientist for the International Space Station. "The system takes the liquid from the air and the urine of the crew and recycles it and purifies it into potable drinking water."
"It seems kind of gross, but that's actually a huge waste stream generating on the station, and we've got to get that (used) water back. We can't afford to waste it," said Layne Carter, who helped develop the water collection and processing system for NASA.
The space station's filtration and sterilization system follows a similar process as the procedure on Earth, but the absence of gravity requires a few extra steps.
"Microgravity makes it much more difficult to actually process the water," Carter said.
To function in space, engineers had to create a mechanism that separates liquids and gases by spinning the liquid, since buoyancy cannot pull them apart, before using particulate filters to take out nonrecyclable inorganic materials and dissolved organic substances.
"Another problem is solids," Carter said. "In ground applications, particles just settle out to the bottom of the tank and they're very easy to deal with. On the space station, there's no gravity, and these solids have a tendency to always go in the worse possible location and cause a failure."
Engineers also had to design a durable, reliable, and relatively small purification system that could withstand the vibrations, loud noises and gravitational forces encountered during transportation to the space station aboard a space shuttle.
"That potable water goes back to the crew for drinking water, for hygiene functions, for food preparation, and then it's also provided to the oxygen generation system," Carter said. "The water recovery system is reclaiming about 1,100 gallons of water each year."
The webcast was facilitated by NASA's Digital Learning Network and Teaching From Space Office. For more information, visit: http://www.nasa.gov/education
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Rachel Kraft/NASA Johnson Space Center Public Affairs Office