1996-012A
The STS-75 mission saw the reflight of the Tethered Satellite System. Launch came on Feb 22, with a scare for the crew as one main engine indicated only 40 percent thrust. Ground controllers quickly reported that it was an instrumentation error. Another problem was discovered retrospectively: for the first time, wiper O-rings in the SRB case-to-nozzle joints were each scorched in two places. Early flights had seen occasional single scorch marks, but never two. The wiper rings were not pressure seals, but merely protected the real seals from contamination prior to launch. However, with the tenth anniversary of Challenger's loss fresh in everyone's mind, the news sparked an investigation.
TSS deployment was originally scheduled for Sep 24 but problems with a computer relay caused a postponement. After a delay of one day, the TSS-1 satellite began to deploy late on Feb 25. After a few hours, it was reaching its maximum extent of 20.7 km (it actually reached 19.695 km) when the tether snapped. The break came at the deployer end of the tether, and the frayed ends were imaged by on board cameras. Rapidly, the tether separated from the Shuttle and TSS-1 entered an orbit with an apogee 100 km higher, inadvertently demonstrating the non-propulsive orbital maneuvering capability of tethers. TSS-1 did record emissions from Columbia's electron guns while orbiting on the other side of the planet. A rendezvous with TSS was considered but turned down due to lack of propellant.
During the tethered phase, TSS demonstrated its electrodynamic current generation capability, generating voltages up to 3500 V and currents to 0.58 amp while Shuttle thrusters were contributing plasma to the vicinity.
Work now began on USMP-3 operations, with astronauts practising minimizing disturbances to the spacecraft to allow crystal growth to proceed successfully. 10 RCS burns were made to support USMP-3. A pass at 85 km from TSS-1 on Mar 1 allowed more data to be obtained from the free flying satellite.
On Mar 5, the astronauts again visually inspected the defunct TSS during a close pass. The mission was extended by one day to allow more USMP-3 experiments. Landing was set for Mar 8.
The Orbiter carried the first three advanced TPS tiles for the X-33 program on its underside.
| STS 75 | |||
| Date | Time | Event | Orbit |
|---|---|---|---|
| 1996 Jan 24 | To VAB | ||
| 1996 Jan 25 | Mate with ET/SRB on MLP-3 | ||
| 1996 Jan 29 | 0733 | Rollout to LC39B | |
| 1996 Feb 22 | 2018:00 | Launch | |
| 2020:06 | SRB sep T+126.3s | ||
| 2026:28 | MECO | 73 x 299 x 28.5 (OMS dV) | |
| 2026:48 | ET-76 sep | ||
| 2057:52 | OMS-2 2:24 67.6m/s | ||
| 2100:17 | OMS 2 CO | ||
| 2110 | 90.53 298 x 303 x 28.5 | ||
| 2144 | PLBD open | ||
| 1996 Feb 24 | 1800 | 90.49 295 x 301 x 28.5 | |
| 1996 Feb 25 | TSS boom raised to 12m | ||
| 2045 | TSS-1 flyaway | ||
| 2145 | TSS-1 at 257m (STS-46 max length) | ||
| 1996 Feb 26 | 0052 | 13.0 km of tether, 1600V/0.42A | |
| 0129:35 | Tether breaks at 19.7 km | ||
| TSS sep at 24 m/s | |||
| 1400 | 90.44 291 x 299 x 28.5 | ||
| Tether retracted | |||
| 1858 | Boom retracted | ||
| 1996 Feb 28 | 1803 | PRCS-1 25s | |
| 2018 | PRCS-2 | ||
| 1996 Feb 29 | 1828 | PRCS-3 | |
| 2043 | PRCS-4 10s | ||
| 1996 Mar 1 | 0517 | Pass 85 km from TSS-1 | 90.35 287 x 296 x 28.5 |
| 1996 Mar 2 | 1400 | 90.32 284 x 295 x 28.5 | |
| 1996 Mar 4 | 0600 | 90.27 282 x 293 x 28.5 | |
| 0848 | PRCS-5 10s | ||
| 1996 Mar 6 | 0600 | 90.22 279 x 290 x 28.5 | |
| 0846 | PRCS-5D (MEPHISTO) 15s 2m/s | ||
| 1043 | PRCS-5C1 (MEPHISTO) 15s 1m/s | ||
| 1046 | PRCS-5C2 15s 1m/s | ||
| 1248 | PRCS-5E (rotation) | ||
| 1303 | 90.13 277 x 284 x 28.5 | ||
| 1996 Mar 7 | 0600 | 90.13 277 x 283 x 28.5 | |
| 0908 | PRCS-6 15s 1m/s | ||
| 1021:00 | MEPHISTO OMS-3 30s 15m/s | ||
| 1021:31 | OMS-3 CO | ||
| 1100 | 90.53 278 x 322 x 28.5 | ||
| 1996 Mar 8 | 1204 | Closed PLBD | |
| 1445 | Landing cancelled | ||
| 1506 | Open PLBD | ||
| 1996 Mar 9 | 0844 | Close PLBD | 90.50 277 x 320 x 28.5 |
| 1255:43 | OMS deorbit 3:34 109.7m/s | 88.02 31 x 320 x 28.3 | |
| 1259:17 | OMS DO CO | -87? x 320 x 28.5 | |
| 1326:45 | EI | ||
| 1358:21 | MGTD KSC RW33 | 15:17:40:21 | |
| 1358:36 | Nose gear down | ||
| 1359:25 | Wheels stop | ||
| 1740 | To OPF | ||
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