ground segment

This term is defined in ECSS-E-ST-70C as
ground systems necessary for the preparation or execution of mission operations

This term is defined in ECSS-S-ST-00-01C as
part of a space system, located on ground, which monitors and controls space segment element(s)

This term is defined in ECSS-Q-ST-30-09C as
all ground infrastructure elements that are used to support the preparation activities leading up to mission operations, the conduct of mission operations and all post-operational activities