STS093-(S)-015 (28 July 1999) --- Following the landing of the Space Shuttle Columbia on July 27, 1999, this medium close-up low-angle view of the three main engines shows what appears to be three small holes in the liquid hydrogen tubes inside the nozzle on main engine No. 3. Engineers will examine the engine to determine if a possible hydrogen leak occurred during the STS-93 launch on July 23.