Last spring, NASA selected the UMR team as one of 72 to fly an experiment aboard the vomit comet, the plane that doubled as a command module for Tom Hanks and other cast members during the filming of the movie Apollo 13. The goal of the team's complex experiment: to determine whether welds could be formed without gravity. If so, future space travelers would have an easier time of building space stations.

"Any advance in making construction in space easier is beneficial. If a means by which welding can be done easily and reliably can be developed, it would be very useful to future construction in space," says Hank Pernicka, associate professor of mechanical and aerospace engineering. Pernicka and Hai-Lung Tsai, professor of mechanical and aerospace engineering, are the team's advisors.

In late April, the team traveled to Houston to board the KC-135 but was unable to get the experiment to work on the ground. The students learned that their welding machine, which used robotics to move the pieces to be welded together, would need some adjustments. "The biggest issue was with the rollers that move the weld strips under the welder like a series of rolling pins," says David Harris, a senior in aerospace engineering. "The rollers were originally made from the same material as the test strips, and they wore down and couldn't grab the strips anymore. It was a time-consuming process to machine new rollers."

NASA invited the team back in July to try the experiment again. "One of the NASA personnel made the comment that our experiment was by far the most technically ambitious NASA had ever seen from a team of undergraduate students," says Harris. "So I think we did an incredible job to get it done on time."

The team welded eight different samples during two, two-hour flights aboard the KC-135, which flies in parabolic patterns to create a temporary environment of near weightlessness. It zooms from approximately 24,000 feet to roughly 32,000 feet and then back down in an arc, generating enough inertia to create about 25-second spurts of microgravity.

"It was an amazing experience and we successfully completed our experiment," says Harris.

Since their return, the students have been evaluating how their microgravity welds held up in comparison to welds done on Earth by examining cross-section views of the welds under the microscope. "One of the most important things we discovered about the welds made in microgravity is that there's a lot of porosity in the welds -- it basically looks like the surface of the moon -- and that weakens it," says Harris. "The other difference is that on the ground, the weld penetrates farther."

Now that the students know there's a clear difference in weld quality, their next question is how zero-gravity welds could be fixed to be as strong (or at least strong enough) to build a structure in space. "I think the significant part of that question is strong enough," says Harris. "While the lower weld penetration and extra porosity weaken the weld, they are about half as strong. So we may introduce a factor of safety of 2.0 whenever we're constructing something with welds in microgravity. Basically that says we expect this weld to be half as strong and we're designing in consideration of that,"

The students have submitted three proposals to NASA's Reduced Gravity Student Flight Opportunities Program and will learn in early December whether they will take another ride on the vomit comet.