Research Partners Developing Trash Dryer for Space Waste

In space, no one takes out the trash. Garbage can pile up, spoil, and become a health hazard for astronauts in the cramped living quarters of a space station.

There has never been a good system for dealing with space waste -- the space shuttle now brings full trash bags back to Earth; on the Russian space station MIR, junk would accumulate in hallways for months before it was sent to burn up in the Earth's atmosphere.

And that is why Jean Hunter, associate professor of agricultural and biological engineering at Cornell University, has been working with research partner Orbital Technologies Corp. (ORBITEC) of Madison, Wis., to develop a cutting-edge trash dryer for NASA, according to a Nov. 18 press release. The space agency will need a new solid waste strategy before it sends astronauts on extended missions to Mars or an outpost on the moon.

Hunter's group has developed a system that blows hot, dry air through wet trash and then collects water from the warm, moist air that emerges. This water can be purified for drinking, and the remaining trash is dry, odorless, and inert. The air and the heat are both recycled to contain odors and save energy.

Heat-pump dehumidification drying, as the technique is called, which has commonly been used for drying lumber, needs to be adapted for space, though, because existing systems depend on the Earth's gravity and contain materials unacceptable for spaceflight. Hunter's team, including graduate student Apollo Arquiza, Jasmin Sahbaz , Carissa Jones, and high school student Trudy Chu , has been testing the dryer with a mix of paper towels, duct tape, baby wipes, and dog food (to simulate the astronauts' food scraps).

A prototype heat-pump dryer is currently being tested at the NASA Ames Research Center. If NASA selects the Cornell/ORBITEC model over dryers developed by competing groups, ORBITEC will make a prototype that performs under zero gravity, is small and light enough for a spacecraft, and can survive the rigors of a rocket launch.

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