1998-034A
STS-91 was the final US mission to Mir, recovering long-stay astronaut Andy Thomas. Veteran space station designer, former cosmonaut, and Mir program manager Valeriy Ryumin, following a strenuous weight loss program, joined the STS-91 crew to carry out a brief inspection tour of the Mir station. STS-91 also carried the flight test of the Alpha Magnetic Spectrometer (AMS), a particle physics experiment. Most crucially, the launch of STS-91 featured the first test of the Al-Li superlightweight external tank, which performed correctly.
The Ku-band TV system failed, so TV coverage of the docking was curtailed and science downlink from AMS was severely hampered. An r-bar rendezvous was followed by docking on Jun 5, using an improved APAS docking mechanism for ISS. As soon as the hatches were opened, Thomas became part of the Discovery crew. Ryumin floated in to Mir for the first time to begin his inspection. During his stay, the crew celebrated the moment he reached a career total of 365 days in space. The DCAM and PCG GN2 experiments were recovered from the Mir. The GMSF experiment was delivered. 12.5 CWC containers with 550 kg of water were delivered.
After undocking, a flyaround failed to spot flourescent gas being injected into Spektr by the EO-25 crew.
On Jun 9, a software problem in the experimental onboard GPS navigation system triggered a series of events which by Jun 10 led to the Shuttle systems computers being overloaded with error messages and failing to select the correct communications antennas, leading to a temporary loss of communication with the ground. Investigation led to software fixes and a decision to require further flight testing of the GPS system before it completely replaced the old TACAN navigation system.
Discovery remained in orbit carrying out work with AMS, which send down enough data to verify detection of anitprotons, but not enough to fully calibrate the instrument. The SHUCS communications experiment also ran into problems. On Jun 11, radio telescope observations of an RCS firing were used to study the effect of thruster plumes on the ionosphere.
OMS-2 mass was 114809 kg.
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| STS-91 |
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| Date | Time | Event | Orbit |
|---|
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| 1997 Oct 1 | | Tow to VAB/2 |
| 1997 Oct 30 | | Tow to OPF/2 |
| 1998 Apr 27 | | Roll to VAB/1 |
| 1998 Apr 29 | | Mate to SLWT |
| 1998 May 2 | 0726 | Roll to LC39A |
| 1998 Jun 2 | 2206:17 | SSME ignition |
| | 2206:24 | Launch |
| | 2208:25 | T+2:01 SRM cutoff |
| | 2208:27 | T+2:03 SRB sep |
| | 2214:54 | T+8:30 MECO |
| | 2215:13 | T+8:49 ET sep | 74 x 324 x 51.6 |
| | 2250:34 | T+44:10 OMS-2 1:45 51.5m/s |
| | 2252:20 | T+45:56 OMS-2 C/O | 90.18 239 x 326 x 51.6 |
| | 2350:02 | PLB Open |
| 1998 Jun 3 | 0147:42 | OMS-3 raise peri 55s 26m/s |
| | 0148:36 | OMS-3 C/O | 91.09 326 x 329 x 51.6 |
| | 1434:14 | OMS-4 R Raise apogee 19s 4m/s |
| | 1434:33 | OMS-4 C/O | 91.24 327 x 343 x 51.6 |
| | 2045 | | 91.23 333 x 336 x 51.6 |
| | 2123:32 | OMS 5 Raise apogee 28s 13m/s |
| | 2124:00 | OMS-5 C/O |
| 1998 Jun 4 | 0000 | | 91.71 342 x 374 x 51.6 |
| | 0600 | | 91.70 342 x 373 x 51.6 |
| | 1036 | Rendezvous begins |
| | 1159:00 | OMS-6 R burn 31s 7m/s |
| | 1159:32 | OMS-6 C/O |
| | 1334:38 | TI RCS |
| | 1354:43 | MC1 |
| | 1425:55 | MC2 |
| | 1442:55 | MC3 |
| | 1452:55 | MC4 |
| | 1645 | Stationkeep at 10m |
| | 1650 | Resume approach |
| | 1658:19 | Docked with Mir SO |
| | 1712:00 | Hard dock |
| | 1806 | | 92.03 370 x 378 x 51.6 |
| | 1828 | Hatch open |
| | 2205 | Thomas part of STS crew |
| 1998 Jun 6 | 0600 | | 92.03 370 x 378 x 51.6 |
| 1244 | RMS test, uncradle |
| | 1513 | RMS recradle |
| | 1756 | Spektr gas release test |
| | 1806 | Release complete |
| 1998 Jun 8 | 0600 | | 92.03 368 x 379 x 51.6 |
| 1307 | Hatches closed |
| | 1557 | Begin undocking |
| | 1601:46 | Undocking from Mir SO |
| | | Stationkeep at 75m on r-bar |
| | | Flyaround Mir to v-bar |
| | | Stationkeep at 60-80m on v-bar |
| | 1643s | Spektr tracer gas experiment |
| | 1705s | Flyaround continues |
| | 1727:00 | RCS Sep burn 1m/s 12s |
| 1998 Jun 9 | | RMS tests |
| 1998 Jun 11 | 0600 | | 91.99 367 x 376 x 51.6 |
| 1630:00 | OMS-7 SIMPLEX, Lower perigee 12s 6m/s |
| | 1630:12 | OMS-7 C/O | |
| 2200 | | 91.78 350 x 372 x 51.6 |
| 1998 Jun 12 | 0629 | | 91.78 350 x 373 x 51.6 |
| 1418 | PLBD closed |
| | 1652:25 | OMS-8 DO 4:10 126m/s |
| | 1656:35 | OMS C/O |
| | 1728 | Entry interface |
| | 1800:24 | Landed at KSC RW15 9d/19:53:54 |
| | 1800:27 | NGTD |
| | 1801:28 | Wheels stop |
| 1998 Jun 13 | 0145 | Tow to OPF/2 |
