STS-91 Day 6 Highlights

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On Sunday, June 6, 1998, 6:00 a.m. CDT, STS-91 MCC Status Report # 10 reports:

The astronauts and cosmonauts aboard the Discovery-Mir complex were awakened at 3:06 a.m. Central time today to the sounds of "Travelin' Band" by Credence Clearwater Revival to begin their final full day of docked operations. Today's activities include the final transfer of water and logistical supplies, preparations for tomorrow's undocking of the two spacecraft, and a photo and video survey of the interior of the Russian space station.

So far, the crew has transferred nine bags of water weighing nearly 900 pounds to Mir; another three or four bags are yet to be transferred. Nearly all of the Russian resupply items - about 2200 pounds --have been transferred from Discovery to Mir, with some U.S. items to be returned to Earth from the Mir yet to be moved to the shuttle.

Among the science items to be transferred to Discovery today is the COCULT experiment, which is a testbed for the growth, maintenance and study of long-term on-orbit cell growth for tissue engineering. In this experiment, a human endothelial cell line and a human breast cancer cell line were cultivated. The procedures used in engineering this specific type of tissue model may be of great benefit in the development of engineered tissue models of normal tissues in future experiments.

At 11:30 a.m. Central time, all nine astronauts and cosmonauts will gather for a joint news conference and farewell ceremony. This event, which is expected to last about 40 minutes, will include brief statements from Commander Charlie Precourt and Mir 25 Commander Talgat Musabayev, followed by questions from U.S. and Russian reporters. An informal farewell between crewmembers will wrap up this morning's events. The crew members final farewell, hatch closing and undocking will take place Monday morning with the physical seperation of the two vehicles for the last time planned at about 11 a.m. Central time.

Later today, Mission Specialists Franklin Chang-Diaz, Wendy Lawrence and Janet Kavandi will conduct a brief evaluation of the maneuverability of moving a bundled spacesuit through the Orbiter Docking System passageway. Information from the evaluation may assist in preparations for assembly of the International Space Station.

Discovery's crew also has been asked to cycle the circuit breaker on one of the cameras in the rear of the shuttle's payload bay in an attempt to restore the camera's function for use in recording Monday's Spektr leak detection test, planned during the shuttle's flyaround of the station. Plans for the choreography of the final leak detection test will be discussed in a tagup by the nine crew members this afternoon.

On the eve of the last undocking by a shuttle from the Mir, the Shuttle-Station complex is orbiting at an altitude of 207 nautical miles circling the Earth once every 92 minutes.

On Sunday, June 6, 1998, 6:00 p.m. CDT, STS-91 MCC Status Report # 11 reports:

The STS-91 astronauts and Mir 25 cosmonauts are concluding their final full day of joint docked operations today as the two crews work to wrap up transfer activities between the two vehicles. Approximately 1200 pounds of water and almost 4,700 pounds of resupply material or return items will have been moved between the two vehicles before the hatches between the two spacecraft are closed for the final time.

Among the science items transferred to Discovery earlier today was the COCULT experiment, which is a testbed for the growth, maintenance and study of long-term on-orbit cell growth for tissue engineering. In this experiment, a human endothelial cell line and a human breast cancer cell line were cultivated. The procedures used in engineering this specific type of tissue model may be of great benefit in the development of engineered tissue models of normal tissues in future experiments.

In addition to their transfer work, Discovery's crew also performed a photo survey of the Mir station and conducted a fit check to insure that the stowed configuration of the EMU space suits used for EVA space walks fit through the airlock hatchway leading into the Mir in preparation for the EMU transfers activity that will be done aboard the future International Space Station.

Late this morning, the astronauts and cosmonauts gathered for a joint news conference during which they answered questions from news media in both the United States and Russia. Astronaut Andy Thomas described his reactions as he nears the end of his four month space flight and = several of the crew members discussed the activities they have been involved with over the last three days and their feelings of being part of the final Shuttle-Mir docking mission.

Following the press conference, STS-91 Commander Charlie Precourt and Mir 25 Commander Talgat Musabayev and their crews held a farewell ceremony during which they gave thanks to the flight control teams in the U.S. and Russia and the other organizations that have supported the Shuttle Mir Phase One program over the last four years.

Near the end of their work day, the two crews gathered together to review both the status of transfer activities as well as the plans for tomorrow morning's undocking.

The STS-91 astronauts are scheduled to begin an eight hour sleep period at 7:06 p.m. CDT this evening.

When Discovery's crew is awakened early Monday morning, the STS-91 crew will immediately move into undocking preparations. A final farewell between the two mission commanders and closing of the hatches between Discovery and Mir is scheduled to take place at 7:41 a.m. CDT. A little less than 3 =BD hours later, the Shuttle will undock from the Russian facility while the two spacecraft are flying over the western portion of Russia at a location of 51.27 North, 33.31 East, southwest of Moscow.

When Discovery undocks from Mir, the initial separation will be performed by springs that will gently push the shuttle away from the docking module. Both the Mir and Discovery will be in a configuration called "free drift" during the undocking, which keeps the steering jets of each spacecraft shut off to avoid any inadvertent firings.

Once the docking mechanism's springs have pushed Discovery away to a distance of about two feet from Mir, and the two spacecraft are clear of one another, Discovery' steering jets will be turned back on to increase the separation distance between the two vehicles.

The shuttle will continue to back away through a corridor similar to that used during approach until it reaches a distance of approximately 2403,000 feet below the Mir. Pilot Dom Gorie will then perform a nose forward fly-around of the station.

During the fly-around, about 20 minutes after undocking, Discovery will reach a point about 240 feet directly in front of the Mir, on what is known as the velocity vector. About three minutes prior to sunrise, Mir 25 Commander Talgat Musabayev and Flight Engineer Nikolai Budarin will release a tracer gas comprised of acetone and biacetyl into the depressurized Spektr module using a special device attached to the Spektr's modified hatch.

The release of gas into Spektr should last about 20 minutes, enabling Discovery's astronauts to document any ionization glow from the gas through the hole in Spektr's hull prior to sunrise and any fluorescent glow from the gas after sunrise. If lighting conditions are right, the gas could appear as a dull green cloud. The test is designed to = pinpoint the location of the breach in Spektr's hull resulting from last year's collision of a Progress resupply ship with the Russian station. Two = days earlier, a similar release of gas into Spektr will be conducted by the cosmonauts while Discovery is docked to Mir to test the gas release system and enable the crew members to document any areas of special interest for the fly-around experiment.

Finally, almost an hour and a half after undocking, Gorie will fire Discovery's jets one more time as the shuttle passes directly above the Mir to separate from the Russian station for the final time.

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