At Launch Pad 39A, the filling of Discovery’s external fuel tank with about 500,000 gallons of chilled liquid oxygen and liquid hydrogen is now complete. These propellants will fuel the shuttle’s three main engines during the ascent to space. The fueling process, known as “tanking,” began at 9:28 p.m. EDT and finished at 12:21 a.m. The propellants will remain in “stable replenish” mode, keeping them filled at 100 percent throughout the remainder of the countdown.
The countdown remains in a planned hold at T-3 hours, and the clock will resume at 2:26 a.m. Both the Closeout Crew and Final Inspection Team are now on their way to Launch Pad 39A. The inspection team will conduct their top-to-bottom “walkdown” of the shuttle and pad, looking for any debris that could damage the vehicle during launch. The Closeout Crew will prepare for the astronauts’ arrival at approximately 3 a.m.