BackForward Satellite Programme: Advanced Composition Explorer 

Programme details
Programme description
  • Single satellite programme for solar-terrestrial interaction studies.
  • USA programme: NASA responsible of development and operations.  NOAA involved in data exploitation.
  • The platform is spin-stabilised, with the spin axis in the direction of the Sun.
  • The design life time of the satellite is 2 years.
  • The satellite is placed at the L1 Lagrange libration point (1,500,000 km from the Earth surface in the Sun direction.
  • See detailed description at
Data circulation
  • Real-time data downlinked each day in 3-4 hours to the NOAA Space Environment Center (SEC) at Boulder, CO; and to several stations of the NASA/GSFC network
  • The ACE Science Center is at the Space Radiation Laboratory of the California Institute of Technology (Caltech), Pasadena, CA.
Agencies NASA
Programme lifetime 1997 - 2027
Associated satellites and instruments

Note: red tag => no longer operational , green tag => operational , blue tag => planned