The Advanced Composition Explorer was launched in August 1997. Like SOHO, it also orbits at the Lagrange point, 1/100th of the distance from the Earth to the Sun. ACE has a variety of instruments, which sample the solar wind. It can detect shock waves ploughing through the solar wind towards the Earth. When reporting space weather, ACE can provide an advance warning (about one hour) of geomagnetic storms that could overload power grids, disrupt communications on Earth, and present a hazard to astronauts.