A Purdue-designed and -built experiment  has taken a trip to space on the last commercial flight of Virgin Galactic’s VSS Unity spacecraft. It is one of just 9 experiments that the ship carried to space, along with its human crew, on this historic flight.

This Rotational Slosh Experiment, funded through NASA’s Flight Opportunities program, was spearheaded by AAE professor Steven Collicott as its principal investigator. Collicott has had dozens of his students work on this project since 2019 — with 10 students involved in the Spring 2024 semester alone — through his Zero Gravity Flight Experiments course, AAE 418.

“My funded research program incorporates the 418 course, so students are getting real-world microgravity experience as undergrads,” Collicott says.

Four students accompanied Collicott to New Mexico to see the experiment off on its flight test: Trey Hackman, Jack Martin, Alex Edwards and Ryan Williams.

The type of research this automated experiment will do is impossible to conduct on Earth, Collicott says. You need some way to get the test into microgravity, and the Unity is one of very few ways to accomplish that. The contents aboard VSS Unity experience about 3 minutes of weightlessness, perfect for this experiment.

“These are excellent laboratories,” Collicott says. “The research you can do there is unique. Volcanologists go to volcanoes — to do our research, we have to go to space.”

The experiment is conducted inside a fully automated box. Accelerometers detect when the spaceship’s rocket fires up, initiating a countdown to begin the experiment that rotates the small, transparent fuel tanks. They’re filled with two liquids, one that repels water (hydrophobic) and one that attracts water (hydrophilic). Dyes help to visualize the differences in how they interact. A camera pointed at these tanks records the results.

Studying this footage will yield a better understanding of how these liquids behave in microgravity. This will give important insight into how fuel tanks for satellites can be better designed to reduce the effect of fuel slosh on a craft’s maneuverability.

The experiment summary published by Virgin Galactic provides additional detail:

“When spacecraft are accelerating in space, such as during a pointing maneuver, re-orientation burns for docking, or to transfer to a new trajectory, it sets the liquid in propellant tanks in motion. After the thruster firing ends, the liquid motion slows down in the zero-gravity environment. This experiment will study the rate of damping of liquid motion after a rotational maneuver. The results will use this additional understanding of low-g propellant slosh to improve spacecraft pointing and mission operations. With the ongoing small satellite revolution, this experiment can use actual propulsion tank sizes for small satellites, rather than sub-scale mock-ups of tanks for larger satellites. The research can be furthered by studying how green propellants movements may differ from traditional propellants, like hydrazine, in zero-g.”