ESP
was used by the Mission Operations Laboratory at NASA's Marshall Space Flight
Center to schedule payload operations for all Spacelab missions managed by MSFC.
(For astronomy missions another scheduler performs the astronomy-unique
scheduling tasks and would feed the schedule to ESP). The Mission Operations
Laboratory was re-organized in the mid 1990's into the Flight Projects
Directorate and the team that developed and maintained ESP is now part of the
Ground System's Department within that directorate.
ESP was developed as a robust scheduler to produce the detailed schedules for multi-step activities required for payload operations on space missions. The domain of ESP is loosely called "space activity scheduling" as opposed by the job-shop scheduling domain (see comparison table).