Accurate weather forecasts save lives. NASA’s Atmospheric Infrared Sounder (AIRS) instrument, launched on this date 15 years ago on NASA’s Aqua satellite, significantly increased weather forecasting accuracy within a couple of years by providing extraordinary three-dimensional maps of clouds, air temperature and water vapor throughout the atmosphere’s weather-making layer. Fifteen years later, AIRS continues to be a valuable asset for forecasters worldwide, sending 7 billion observations streaming into forecasting centers every day.