Planned docking time at Mir: 4.06.1998 at 1659 UTC. (For Western Europe): During the final stage of the approach of Discovery to Mir both objects will be in our range during Mir's orbit 70210, 1649-1657 UTC. Then radio traffic might be possible on the following channels: 143.625 mc (Mir-TsUP Moscow), 130.165 mc (Mir-Discovery) and 121.750 mc (not likely). Traffic from Mir via Altair-2 with TV-images of the approaching Shuttle are also possible during that orbit between 1613 and 1707 UTC if this satellite will be used for that purpose. And there is a chance that images from the Shuttle of the Mir complex via a TDRS and relayed by CNN reach us if the editors do not attach a higher priority to other subjects.

Attitude control problems solved:

During the period in which the Mir crew was solving these problems the attitude control was done by small thrusters of the Mir complex itself and Soyuz-TM27. The replacement of the attitude control computer by a new or by an old spare one did not help. TsUP transmitted to Mir the needed software. After loading this into the computer the word 'error' appeared on the screen. After the replacement of the Omega star tracker in the Kristall module or switching over to a reserve one the attitude control was activated again and worked well.

In the morning of 2.06.1998 the Russians successfully concluded the necessary tests and they started to activate the 11 gyrodynes. In the course of 2.06.1998 all gyrodynes spun at their maximum speed thus securing the accurate attitude control badly needed for the approach and docking of Discovery on 4.06.1998. Moreover Russian experts had stated that approach and docking also were possible when the attitude control was done by thrusters, but thus far this had not been necessary during previous Shuttle operations and consequently this has never been tried out.

During the period in which the crew was repairing and testing the attitude control systems radio traffic could be monitored far into the night. During these communications Musabayev got commands from TsUP and loaded these into the systems Svet and Simvol.

Altair-2:

A considerable time there were no communications via this geostationary satellite. This is quite normal in periods in which the attitude cannot be maintained by the gyrodynes.

Chris v.d. Berg, NL-9165/A-UK3202.