The instructions are transmitted as a list of commands known as a sequence. Sequences are developed by team members and rigorously tested for errors. They contain each step of each activity the spacecraft is to perform.
To maintain contact with TOPEX/Poseidon the team must schedule coverage time with the TDRSS or the Deep Space Network. This ensures that engineers at these facilities will be available to transmit the sequences, and will be "listening" when TOPEX/Poseidon sends a return signal.
The MPST also manages the onboard tape recorders to determine when data collected by TOPEX/Poseidon will be transmitted back to earth.