The ACS provides telemetry, tracking and command as well as voice communications functions to and from the ISS and the Ku-band Space-to-Ground
Antenna System (SGANT), providing video and high data-rate scientific data communications.
There, during late evening hours, TDRS-7's giant solar panels, which tip to tip are taller than a five-story building, and Ku-band space-to-ground
and S-band omni antennas were deployed, and the IUS separated and maneuvered away from the satellite.
Before TDRSS, NASA relied solely on a system of ground stations that permitted space-to-ground
communications only 15 percent of the time.