KSC-99pasparklers

Moments before launch, sparks from the external ignitors are visible below the engines of Space Shuttle Columbia. The ignitors burn off a hydrogen concentration outside the orbiter near the main engines. A cloud effect behind the Shuttle's solid rocket booster and access arm to the left is created by spray from the water deluge system. The launch of STS-93 was scrubbed at the T-7 second mark in the countdown due to an indication of a high concentration of hydrogen in an aft engine compartment. The reading was proven to be a false alarm. The launch is rescheduled for July 22 at 12:28 a.m