Un-tethered Sentry (IMAGE) U.S. National Science Foundation Caption Once launched, Sentry operates without being tethered to a ship, pre-programmed for the areas it is to map. Credit University of Washington Usage Restrictions None 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.