T-Cell (IMAGE) NASA/Johnson Space Center Caption At specified times during the T-Cell Activation in Aging study, the International Space Station's crew will use hand-operated tools to add activation and fixative materials to experiment units like the one seen here. Credit Millie Hughes-Fulford Usage Restrictions Millie Hughes-Fulford License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.