STS-91 Day 7 Highlights

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On Monday, June 8, 1998, 6:00 a.m. CDT, STS-91 MCC Status Report # 12 reports:

The STS-91 astronauts and the Mir 25 cosmonauts will part company today, with the Space Shuttle Discovery scheduled to undock from the station at 11:01 a.m. Central time, officially ending the three years of shuttle dockings and astronaut flights aboard the Russian complex.

Discovery will be bringing home astronaut Andy Thomas, who has been in space since Jan. 22. If Discovery lands as planned on Friday, the seven Americans who have stayed aboard Mir will have spent a combined total of 977 days in space.

Discovery's crew was awakened at 3:06 a.m. Central today to "Manic Monday" performed by The Bangles, played to the crew by Mission Control in honor of an historic Monday for the U.S. and Russian space programs. Today's schedule includes possible television from the Mir of a final crew farewell and hatch closing at 7:51 a.m. Central; possible television of Discovery's undocking from Mir at 11:01 a.m. Central as the spacecraft fly above Russia, southwest of Moscow and north of the Ukrainian border; possible television of Discovery's flyaround of the Mir at 12:05 p.m. Central; and possible television scenes from the shuttle through U.S. ground communications stations at 3:22 p.m. Central.

During the four days Discovery has been docked to the Mir, more than 1,100 pounds of water and almost 4,700 pounds of cargo, experiments and supplies have been exchanged between the two spacecraft.

After undocking, the shuttle will back away from the Mir until it reaches a distance of approximately 240 feet below the station. Pilot Dom Gorie will then perform a nose forward flyaround of Mir. About 20 minutes after undocking, as Discovery reaches a point about 240 feet directly in front of the Mir, Mir 25 Commander Talgat Musabayev and Flight Engineer Nikolai Budarin will release a tracer gas of acetone and biacetyl into the depressurized Spektr module. The gas release into the damaged module will begin about three minutes before sunrise and should last about 20 minutes, hopefully enabling Discovery's astronauts to document the dull green, luminescent gas as it passes through the hole in the Spektr module's hull. The test is hoped to pinpoint the location of the breach in the Spektr that resulted from last year's collision of a Progress cargo ship. Finally, almost an hour and a half after undocking, Gorie will fire Discovery's jets as the shuttle passes directly above the Mir to separate from the vicinity of the Russian station.

After undocking, experiment work will continue aboard Discovery, including Alpha Magnetic Spectrometer (AMS) science operations and checks of the SPACEHAB Universal Communications System (SHUCS) system. The AMS instrument is hoped to provide scientists insight into the existence of dark matter and antimatter in the universe. The SHUCS is a communications system which may allow future scientists to communicate directly with astronauts conducting experiments in the Spacehab module.

The Discovery-Mir space complex is orbiting the Earth at an altitude of 239 statute miles with all systems ready to support undocking. The next STS-91 status report will be issued at about 6 p.m. Central time Monday.

On Monday, June 8, 1998, 6:00 p.m. CDT, STS-91 MCC Status Report # 13 reports:

Three years after Space Shuttle Atlantis accomplished the first docking to the Mir space station, the STS-91 crew aboard Discovery undocked from the orbiting Russian complex this morning to conclude the ninth and final Shuttle-Mir mission. Joining the STS-91 crew for the trip home is NASA astronaut Andrew Thomas, the seventh and final astronaut to serve as a station crew member, returning home after four and a half months in space.

After the hatches between the two vehicles were closed for the final time at 8:07 a.m., the Shuttle and Mir separated on time at 11:01 a.m. CDT while flying above Russia, southwest of Moscow and north of the Ukrainian border. Following separation, STS-91 Pilot Dom Gorie maneuvered the shuttle away from the Mir to a distance of approximately 2403,000 feet below the station. He then performed a nose-forward fly-around of Mir allowing the Shuttle to reach a point about 240 feet directly in front of the Mir at 11:24 a.m.

With Discovery stationkeeping at that position, Mir 25 Commander Talgat Musabayev and Flight Engineer Nikolai Budarin then released a tracer gas of acetone and biacetyl into the depressurized Spektr module. The gas release was done in the hope that the STS-91 crew would be able to see the fluorescent substance as it passed through the hole in the Spektr module's hull, pinpointing the location of the breach in the Spektr that resulted from last year's collision of a Progress cargo ship. No leak source was seen by Discovery's crew.

Finally, at 12:27 p.m., Gorie fired Discovery's maneuvering jets as the shuttle passed directly above the Mir to separate from the vicinity of the Russian station. As of 6 p.m. CDT this evening, Discovery was 28 nautical miles ahead of the Mir with the distance between the two spacecraft growing at eight n.m. each orbit.

Discovery's crew spent the remainder of its seventh day in space stowing items transferred from the Mir in preparation for Friday's landing at the Kennedy Space Center. The crew also continued experiment work, including the Alpha Magnetic Spectrometer (AMS) science operations and checks of the SPACEHAB Universal Communications System (SHUCS) system. Scientists hope the AMS will provide insight into the existence of dark matter and antimatter in the universe. The SHUCS communications system, designed to send and receive telephone voice and data communications globally via three ground stations and the INMARSAT satellite system, continues to experience difficulties. The SHUCS payload team plans to continue troubleshooting and testing of the system tomorrow.

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