ACE analyzes particles blown from the sun and from elsewhere in our galaxy.
The particles ACE detects include galactic cosmic rays, which are fragments of atoms from deep in the galaxy, traveling at nearly the speed of light.
ACE helps us understand the sun, its interaction with Earth, and the Solar System's origin and evolution.
ACE provides about a one-hour warning of space-weather events that could harm electronics and future astronauts. It may help us one day to predict hazardous space weather.
ACE orbits the sun at Lagrangian Point 1 (L1), which is about 930,000 miles (1.5 million km) sunward of Earth.
At L1, Earth's gravity counterbalances that of the sun such that ACE remains directly between Earth and the Sun as the planet and spacecraft orbit the sun.