Atlantis is prepared to depart the Mir space station today following six days of joint operations between the STS-86 and Mir 24 crews. Atlantis is scheduled to undock from the Mir today at 10:43 a.m. Central time while the two vehicles are passing just East of the Caspian Sea over Turkmenistan.
Pilot Mike Bloomfield will back Atlantis away to a distance of about 600 feet below and in front of Atlantis to test navigation sensors, before once again closing in toward the Mir to a distance of 240 feet. He will stationkeep at that range for an hour waiting for sunrise, before beginning a 46-minute fly-around of the Russian station. During the fly-around, Atlantis’ astronauts will conduct visual inspections of the Mir station and use a variety of cameras equipped with high-powered lenses and video equipment for documentation of the Spektr module.
At several points during the fly-around, Mir Commander Anatoly Solovyev and Flight Engineer Pavel Vinogradov will open a pressure regulation valve in the Mir to pulse air into the depressurized Spektr. Russian flight controllers hope Atlantis’ astronauts may detect some seepage of particles or debris from the breach in the hull of Spektr which will assist them in the future planning of repairs to the module.
Once the fly-around is complete, Bloomfield will conduct a final separation maneuver from the Mir at 1:43 p.m. Central time, bidding the Mir farewell and leaving behind Astronaut Dave Wolf.
Early this morning, the Mir crew began replacing an onboard command exchange unit, which acts as a relay between Mir’s main motion control computer and the Kvant module’s gyrodynes and Kurs antenna. Mir’s attitude control gyrodynes will not be spun down for this activity, which will begin at 6:34 a.m. central time and is expected to take two and one-half hours. The replacement will be followed by a brief checkout of the command unit’s systems and if all systems are functioning, the work should be complete about one hour prior to undocking.
Undocking could be delayed by two orbits, or until about 2 p.m. central time, in the event problems are encountered and the Mir crew has to reinstall the existing command exchange unit. While that relay box has been working perfectly in recent weeks and throughout docked operations, it had issued independent commands in the past, and Russian flight controllers elected to install the new unit to provide them with increased confidence in their attitude control capability. The system will be checked out by issuing commands to the inactive Kvant-2 gyrodyne and to the Kurs antenna which is used for automated dockings.
Once Atlantis’ crew has departed from Mir, they will enjoy some off duty time for the remainder of their day on orbit, before beginning a scheduled eight-hour sleep period at 10:34 p.m.
The next STS-86 mission status report will be issued at 8 p.m. central time today.
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