Mastracchio AES (IMAGE) NASA/Johnson Space Center Caption Astronaut Rick Mastracchio works on the Antibiotic Effectiveness in Space-1 (AES-1) investigation during Expedition 38 aboard the International Space Station. Credit NASA Usage Restrictions NASA 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.