Energetic events within the Earth's atmosphere are known to produce infrasonic acoustic waves which can propagate to great distances and induce changes in free electron density within the ionosphere. These waves can be detected using the Global Positioning System (GPS) as fluctuations of total electron content (TEC). The ascent of the Space Shuttle on mission STS-125 produced detectable signal in an array of GPS stations located along the southeastern coast of the United States. The observations show a clear evolution of the waves in time, which separate into dual modes with distance, and are likely related to fundamental acoustic modes of the atmosphere. We reproduce the observed signals using a forward model which verifies the ability of GPS to estimate the acoustic energy release of powerful sources near or at the Earth's surface. Our results also suggest that the majority of observed GPS signal can be explained using a simplified approach to the underlying physics involving only collisions between neutral particles and free electrons in the ionosphere.