Saturday Morning Science: Alka-Seltzer added to spherical water drop in microgravity onboard the International Space Station. (March 22, 2003) --- Expedition Six NASA ISS Science Officer Don Pettit performs a series of microgravity experiments with water spheres and effervescent antacid tablets. In the second of four videos, Pettit inserts a tablet into a 50-millimeter sphere and observes the