Exploring the Ground Truth: NASA's Twin Study Investigates Metabolites (image) NASA/Johnson Space Center Share Print E-Mail Caption NASA astronaut Scott Kelly enjoys his first drink from the ISSpresso machine on the International Space Station. Twins Study investigators saw metabolite levels increase when Scott went to space. Credit NASA Usage Restrictions None Share Print E-Mail 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.