Fact sheet number: FS-2002-03-77-MSFC
On Earth when scientists melt metals, bubbles that form in the molten material can rise to the surface, pop and disappear. In microgravity — the near-weightless environment created as the International Space Station orbits Earth, the lighter bubbles do not rise and disappear. Prior space experiments have shown that bubbles often become trapped in the final metal or crystal sample. In the solid, these bubbles, or porosity, are defects that diminish both the material’s strength and usefulness.
The Pore Formation and Mobility Investigation will melt samples of a transparent modeling material, succinonitrile and succinonitrile water mixtures. Investigators will be able to observe how bubbles form in the samples and study their movements and interactions.
The crew will pull out the large, sealed work area on the Microgravity Science Glovebox and use its ports to install the thermal chamber, cameras, and other data-collection devices. Two cameras collect real-time images of the samples as they are melting and subsequently resolidifying in the thermal chamber.
Images are sent to the investigator on the ground working in a telescience center at the Marshall Center Microgravity Development Laboratory (MDL). From the MDL, investigators can send commands to the experiment, changing temperatures, growth rate and other variables that affect sample processing. Most importantly, scientists will be able to measure bubble size, numbers, movement and other interactions.
Other control and data equipment, including a laptop computer, will be on the right side of the glovebox.
Before flight, scientists will load the succinonitrile samples in transparent tubes 0.39 inches (1 centimeter) in diameter and 7.87 inches (20 centimeters) in length. Twelve to 15 samples will be processed, with each sample run lasting an average of seven hours. During some runs, investigators will try techniques to influence bubble movements and will try to move them, and thus reducing porosity along the sample length.
After the sample ampoule assembly is placed in the thermal chamber, the crew will use the glovebox laptop computer to start the experiment. As the sample ampoule assembly is heated in the thermal chamber with a maximum temperature of 266 degrees Fahrenheit (130 degrees Celsius), the contained material will melt. Then, it will be moved through a cold section where it will be directionally resolidified – in much the same way turbine blades are made. The crew will periodically monitor the sample and change out videotapes at the beginning of each run.
This investigation will be one of the first materials science experiments on the Space Station, and the first flight for this study. This investigation gives scientists an opportunity to observe bubble dynamics in a sample being processed in a way similar to industrial methods. The intent of the experiment is to gain insights that will improve solidification processing in a microgravity environment. The generated data may also promote our understanding of processes on Earth.
For more information on this experiment, the Microgravity Science Glovebox and other Space Station investigations, please visit: