STS-93

Launch, orbit & landing data: Designation  25866 / 99040A Launch date - time  23 Jul 1999 - 04:31:00 UT Launch site  KSC, LC39B Launch vehicle  Space Shuttle Orbiter  Columbia #26 (OV-102) Primary payload  Chandra X-ray Mass (kg)   Flight Crew  Collins, Ashby, Coleman Hawley, Tognini Earth orbit on :    - Perigee / Apogee  283 km    - Inclination  28.4°    - Period   min Landing date - time  28 Jul 1999 - 03:20:35 UT (04:21? ref:#16) Landing location  KSC, Runway 33 Flight Duration (d:hr:min)  4d 22h 50m Nbr orbits  80

Crew

Summary:

Mission details:

• The Chandra spacecraft was connected to the IUS-27 upper stage on Jun 3, 1999 in the Vertical Processing Facility at Kennedy Space Center. On the same day, Columbia was towed from the Orbiter Processing Facility to the VAB and then connected to its external tank and solid rocket boosters to complete the STS-93 stack.
• STS-93 was first rolled out to pad 39B on June 7, 1999. The Chandra/IUS-27 vehicle was placed in the payload canister on June 19. The first launch attempt was on July 20, but controllers aborted the launch at T-6 seconds, just before main engine ignition, due to a data spike in hydrogen pressure data. If it had really been an indication that there was lots of hydrogen leaking into the engine compartement, yhere would be danger of explosion, but this was determined to be due to a faulty sensor.
• A second attempt was on July 22. A lightning storm prevented launch during the 46 minute window, and the launch was again scrubbed. Finally the vehicle lifted off the pad on July 23 at 04:31 UT, but five seconds after launch a short in an electrical bus brought down two of the three main engine controllers. Backup controllers took over, but a further failure on the backup controller bus would have resulted in engine shutdown and the first ever attempt at an RTLS (Return To Launch Site) abort. To further complicate matters engine 3 (SSME 2019) had a hydrogen leak throughout the ascent, causing the engine to run hot. Controllers sweated as temperatures neared redline. The hot engine’s controller compensated as programmed by using additional liquid oxygen propellant. The final result was that the shuttle ran out of gas - main engine cut-off (MECO) was at 04:39 GMT, putting Columbia into a 78 km x 276 km x 28.5 degree transfer orbit. Columbia was 1,700 kg short of oxygen propellant and 5 meters/sec slower than planned. The OMS-2 engine burn at 05:12 GMT circularised the orbit 10 km lower than planned.
• The orbiter payload bay contained only the Chandra spacecraft, the IUS, and the IUS tilt table. The following payloads were carried in the shuttle’s cabin: STL-B (Space Tissue Loss), CCM (Cell culture module), SAREX-II (Shuttle Amateur Radio Experiment), EarthKam, PGIM (Plant Growth Investigations in Microgravity), CGBA (Commercial Generic Bioprocessing Apparatus), MEMS (Micro-electric Mechanical System), and BRIC (Biological Research in Canisters) and SWUIS (the Southwest Ultraviolet Imaging System, an 0.18-m UV telescope to be used for airglow and planetary observations); GOSAMR (the Gelation of Sols: Applied Microgravity Research experiment) and LFSAH, the Lightweight Flexible Solar Array Hinge. MSX and SIMPLEX experiments were also to be carried out.
• At around 1000 UTC the IUS ASE tilt table was raised 29 degrees out of the payload bay, and the Chandra lower antenna was tested. At 1142 UTC the IUS ASE was raised to 58 degrees, the deployment angle. Chandra/IUS-27 was deployed from Columbia at 11:47 GMT July 23. Flight duration was limited; this was the heaviest shuttle (122,534 kg) and heaviest payload (19,736 kg) to that date.
• Columbia landed at 03:20 GMT on July 28 on runway 33 at Kennedy Space Center. Post-flight inspection found the presence of holes in the cooling lines on the nozzle of SSME 2019 (engine 3) which caused a hydrogen leak. A loose repair pin in the engine broke free and caused the failure. The cause of the short was found to be chaffed wiring inside the shuttle. The entire fleet was grounded for inspection and replacement of wiring as necessary.