scope:

Description of Driving Event:

The primary objective of the Advanced Composition Explorer (ACE) Project was to determine and compare the elemental and isotopic composition of several distinct samples of matter, including the solar corona, the interplanetary medium, the local interstellar medium, and galactic matter. The Goddard Space Flight Center (GSFC) and the National Aeronautics and Space Administration (NASA) Headquarters Office of Space Science (OSS) undertook the ACE mission development including the execution phase. The GSFC agreed to launch ACE no later than December 1997 on a not-to-exceed cost basis. The end result was that the mission's actual cost was considerably less than the limit and the launch date was earlier than projected.