yee@trident.arc.nasa.gov (Peter E. Yee) (06/03/90)
Friday, June 1, 1990 12:00 noon Kennedy Space Center Shuttle Status STS-35 -- COLUMBIA (OV-102) - LAUNCH PAD 39-A Technicians continue inspections of the shuttle Columbia's 17 inch disconnect area in attempts to isolate a leak in the liquid hydrogen system that caused managers to scrub Wednesday morning's launch attempt of Space Shuttle Mission STS-35. Overnight, technicians offloaded the contents of the PRSD cryogenic tanks from the orbiter Columbia. Offloading was completed at about 12:30 a.m. this morning. A test of the liquid hydrogen system in the orbiter's aft compartment under higher pressure commenced following PRSD de- tank operations. Using gaseous helium to help isolate the leak, engineers detected a higher than normal leak rate in the cavity between the orbiter and external tank 17 inch disconnect interface plates. No leaks were detected between the interface primary and secondary seals or in the 4 inch feed line seals. However, leakage was detected in the interface cavity. Engineers will continue to monitor the situation with hopes of isolating the exact source and cause of the leak. Trouble shooting on all of the liquid hydrogen lines in the aft compartment of the orbiter is continuing. Based on information assessed overnight, the launch team will not maintain a launch countdown posture on the pad. Therefore, launch of STS-35 will not occur next week. Preparations are currently underway to perform a mini-liquid hydrogen tanking test next Wednesday morning. In preparation for this test, a helium signature leak test will be conducted on the liquid hydrogen side of the main propulsion system Saturday. This will allow technicians an opportunity to gather additional information necessary for the accurate placement of additional leak detection sensors and mass spectrometers. Additional cameras also will be installed on the pad for more accurate visual inspections during the tanking test. Following the helium signature test Saturday, ordnance disconnect operations will take place Sunday. Prior to Wednesday's tanking test, the rotating service structure will be rotated to the park position. The move is scheduled to occur mid- night Tuesday. At this time, managers have decided not to open the orbiter's payload bay doors until further assessments on the liquid hydrogen line are made. BBXRT does not require servicing of argon coolant until June 11. Mission managers will continue to meet to discuss options for a scrub turn-around based on information established during current testing.