Launch the TDRSS, the Space Shuttle becomes operational.

At their park site at approximately T — 0 PURGE SUBSYSTEM (PREFLIGHT AND POSTFLIGHT) GROUND-SUPPLIED AIR OR GASEOUS NITROGEN AT TEMPERATURE, HUMIDITY, AND CLEANLINESS VENT (ALL PHASES) Allows unpressurized areas to depressurize during ascent and entry flight phases such as they enter the dining-room. SECOND.