The discovery of water on the moon announced this week has scientists and spaceflight buffs pumped for a return of humans to the otherwise dusty planet. But in addition to water, anyone who goes there will be looking for some oxygen.

If NASA or any space agency is to set up moon bases, they'll need oxygen and water for breathing, drinking and to create fuel for return flights. Carrying all that stuff up there would be prohibitively expensive if long-term residency is the goal.

NASA had offered $250,000 in prize money in a contest to spur technology aimed at getting oxygen from moon dirt, but it expired in June 2009 after 2 years with no winners.

Now scientists from NASA and Case Western Reserve are designing and testing components of an oxygen generator that would extract the element from silicon dioxide and metal oxides in the lunar dirt. They have designed sifters needed to produce a consistent supply of oxides.

Testing the setup is tricky, however, because gravity here is a lot stronger than there, and tools and machines work differently.

So Katie Fromwiller, a senior civil engineering student, and Julie Kleinhenz, an assistant research professor of aerospace and mechanical engineering, spent two days flying in high gravity-depleting arcs off the Texas coast last month aboard the "vomit comet," a research plane that simulates reduced gravity.

Inside the plane, the pull of gravity approximated the moon's weak gravity ? about one-sixth what we feel on Earth ? during the rapid drop in each arc. (The riders felt twice the pull of the Earth's gravity on the way back up. During two runs, they floated in zero gravity.)

"It was as if they were working on the moon, 20 seconds at a time," said David Zeng, Frank H. Neff Professor and Chair of Civil Engineering from the Case School of Engineering and one of the principal investigators of the study.

NASA engineers were testing other components of the oxygen generator on the same flight.

NASA, Kleinhenz explained in a statement, has plans to build a system that includes a rover that would dig, carry and dump moon soil into a hopper or holding vessel. Sifters would separate particles by size, collecting those that can be converted most efficiently. The particles can also be separated by composition. For example, an electrostatic charger can be used to isolate iron oxides from other soil materials.

The wanted particles would then be blown into a reactor with hydrogen and heated to 2,000 degrees Fahrenheit. At this time, the oxygen released from the oxides would attach to the hydrogen and be collected.

While in flight, the pair tested two kinds of devices, a vibro-sieve and a sifter. As the plane reached lunar gravity, Fromwiller switched on a vibration table that shook a sieve, similar to a perforated pan used to pan for gold. As on Earth, the process worked.

Kleinhenz worked a sifter that operates much like a flour sifter. It, too, was able to separate particles in low gravity.

Zeng and his team are continuing to analyze data produced over the two days. Ultimately, NASA will decide which kind of device to use in the oxygen generator.