Advanced Composition Explorer

NASA's Advanced Composition Explorer (ACE) spacecraft was designed to study spaceborne energetic particles from the Sun-Earth L1 Lagrange point, about 870,000 miles (1.4 million kilometers) from Earth. Specifically, the spacecraft was launched to investigate the matter ejected from the Sun to establish the commonality and interaction between the Sun, Earth and the Milky Way galaxy. In addition, ACE also provides real-time space weather data and advanced warning of geomagnetic storms. As of 2015, it continued to provide near-real-time 24/7 coverage of solar wind parameters and to measure solar energetic particle intensities.