Many astronauts and U.S. space agency officials say the legacy of the 30-year-old space shuttle program is the International Space Station. While the station is hailed as a great scientific laboratory, the shuttles too, hosted thousands of science experiments.
Imagine making a beverage - with dirty water, urine or sweat as the main ingredients. Then add the challenge of making this cocktail in space.
Astronauts aboard the International Space Station are experimenting with the Forward Osmosis Bag system to see if they can create drinkable water in microgravity.
Howard Levine, of NASA's Kennedy Space Center in Florida, is the principal investigator. "Think of it as a bag within a bag. In the outer bag, you can introduce dirty water or water that cannot be drunk by the astronauts. On the interior, the inner clean bag, we introduce a high sugar solution concentrate, and just by osmosis, it cleans the water," Levine said.
NASA says the product was used successfully in disaster relief efforts after the 2010 earthquakes in Haiti and Chile, and it was tested in the southern United States after Hurricane Katrina. Researchers hope it will work in space, too.
"It pulls the water through a semi-permeable membrane, selectively excludes elements, compounds, bacteria, viral particles that are not desirable, and you end with a sports drink that maybe four to six hours later can be drunk by the crew members," Levine said.
If the bag functions in space as researchers hope, engineers want to incorporate this technology into future spacewalking suits. They say small osmosis devices could be part of the space suits, possibly recycling an astronaut's sweat or urine into a drinkable fluid during extended spacewalks.
That's just one of the many experiments being conducted on the space station, but the shuttles themselves have hosted science experiments, too, right down to the final mission of the shuttle era. Among those experiments is Micro-2A, lead by a researcher in her early thirties named Cynthia Collins.
When most people think of a community, they usually think of people.
But Collins studies communities of an entirely different sort. "My lab is interested in bacteria and how bacteria form communities," Collins said.
Collins is an assistant professor of chemical and biological engineering at Rensselaer Polytechnic Institute in New York. She is the principal investigator in a series of experiments about biofilm.
"A biofilm is a community of bacteria that grows on a surface. That's the simplest way to think about it, and so an example would be what you have on your teeth in the morning or on your showerstall," Collins said.
By and large, we don't have much to fear from tooth film or shower scum, but biofilms also form in hospitals and in catheters and those can harbor dangerous bacteria.
So Collins and her research team sent an experiment up on the final mission of the space shuttle Atlantis in order to study the way bacteria act in microgravity. It is just one of more than 2,000 science experiments that have been conducted on the space shuttles during the past three decades.
"Anytime we can get a better understanding of how bacteria respond to changes in the environment, that can give us a better idea of how to treat or understand microbes that are important for life on Earth," Collins said.
To be precise, researchers sent up 16 devices loaded with vials full of bacteria that are often responsible for the types of infections patients get in hospitals. Astronauts aboard the space shuttle Atlantis activated the experiment by churning a hand crank on each device. That action allowed the bacteria to mix with nutrients and a surface where they could form biofilms. Back on Earth, Collins and her team conducted the same experiments. "It's very important for us to minimize infections with quote-unquote 'bad bacteria' or potentially infectious bacteria, but it's also important for us to understand the good bacteria that exist in our body so that we can promote healthy digestion and immunity and, of course, we're hoping to be able to promote that for the astronauts in the longterm, as well," Collins said.
The research team says astronauts have shown an increased susceptibility to infection while in space.
With the end of the shuttle era, NASA officials emphasize the next phase of space exploration is taking place today - in the form of experiments on the International Space Station.
Station Program Manager Mike Suffredini says the space station, which was built in pieces carried up on the orbiters, is the shuttle program's greatest legacy.
"It's going to result in research that is going to benefit humanity and our planet. The things we're going to learn from the ISS, we just don't even know today, and in some cases, don't even fathom yet," Suffredini said.
People have been living and working continuously on the space station for more than 10 years. NASA predicts at least another decade of exciting research opportunities onboard the orbiting lab.