Engineers demonstrated loading, controlling and draining more than 700,000 gallons (2.6 million liters) of cryogenic propellants into the liquid oxygen and liquid hydrogen tanks and then returning the stage to a safe condition. Toward the end of the simulated terminal countdown, the test automatically stopped due to a valve closure being off by a fraction of a second. The team has corrected the timing, and additional analysis clears the way for hot fire.