MIRNEWS.469    6 SEPTEMBER 1999

Change-over of movements regime and other systems on board MIR-space 
station:

On 7.09.1999 (Moscow time) a number of systems will be switched off. The
Ts.V.M.-1 (the Main OBC) will be replaced by the B.U.P.O. (Unit for
Control of Dockings and Orientation). As far as the scarce information
permitted, I gave an explanation of that system in my MIRNEWS.465 of
10.08.99. In fact the B.U.P.O. is a computer and not just an interface.
Until 28.08.99 the crew (mostly the commander) had to load control
commands into the Ts.V.M.-1 read out for them by TsUP. These commands
enabled the computer to control the attitude of the complex and the
optimum efficiency of the solar batteries. During the unmanned status of
the space station, TsUP will load these commands into the B.U.P.O. to
control the movements of the complex, also by steering rockets and the
external thruster V.D.U. to control the roll (rotations around the X-
axis).

On 31.07.99 the B.U.P.O. had been installed prematurely. Due to a mistake
at TsUP the Ts.V.M.-1 failed and this was an opportunity to install the
B.U.P.O., for during that installation the Ts.V.M.-1 had to be off
anyhow. After the installation there came not much information on that
system. The good functioning was reported, but radio traffic did not
reveal whether the system was already operational. Meanwhile the
gyrodynes were still in use for the movements control of the complex.

So on 7.09.99 the Ts.V.M.-1 and the gyrodynes will be switched off. This
means that the complex will enter the so called 'free drift', or as the
Russians say 'indikatornyy rezhim' (indicator mode). The responsible
flight controller at TsUP has to load the control commands into the
B.U.P.O. for the stability of the complex or at least to maintain the
eventual spinning within acceptable limits. It is still unclear to me if
they will make some use of the gyrodynes (for instance those in the Base
Block and/or Kvant-1) for movements control.

The freighter Progress-M42, still attached to the complex, will be used
to raise the orbit of the complex if needed. Theoretically the steering
rockets of the Pr-M42 also can be under direct guidance from the
Progress-M control room at TsUP. (in the past the Soyuz-TM ships have
been used for that purpose). But in my opinion this will not take place
via the B.U.P.O.

Other systems:

The power delivered by the S.E.P. (system for power supply) will be
reduced during the 'free drift' and consequently a lot of systems have to
be switched off. (During the last weeks before their return to earth,
the cosmonauts replaced 2 accumulator batteries in the base block.)

The following systems will continue to work:

The S.O.T.R. (system for thermo regulation), the Telemetry system and
the radio channel for the transmissions of commands (Telekommandnaya
Liniya).

But what can we humble earthlings do? Wait and sit it out or:

1. Radio observers: To try to check as much as possible the telemetry
frequencies during passes of the MIR-complex. (So like the nurse on duty
in the intensive care: to be sure that there is still life.)
2. Visual observers: To do as much visual observations as possible to
determine whether the complex is spinning and if so, at what rate.
3. To use all possible well informed sources to ask dozens of questions
about MIR.

(in the beginning of October this year we can do that in Amsterdam during
the 50th congress of the IAF or the ASE-congress in Romania.)

Hereby very new 2-line elements:

MIR
1 16609U 86017A   99246.61099712  .00045650  00000-0  34340-3 0  8423
2 16609  51.6612 301.9993 0004593 311.0449  49.0179 15.72062698773757

Frequencies:

In the 166 and 165 mc bands, peaks of PCM/FM telemetry around 166.130
and 165.873 mc. Same transmissions possible around 636 and 638 mc.
Monitoring 922.760 mc might be useful.

Progress-M42:

Also in the 166 and 165 mc bands and around 922.750 mc.

Chris van den Berg. NL-9165/A-UK3202.