ISSCOM 9 July 2007 (059)

Summary of communications from the Russian segment of the ISS in the period from 12 May until 9 July 2007.

On 12 May 2007 the freighter Progress-M60 was launched for a flight of two days to the ISS.

During the flight the telemetry transmitters in the 166 and 165 mc could be monitored very well.

On 14 May during ISS orbit nr. 48556 between 0433 and 0439 UTC the signals of the approach systems on 130.165 and 121.750 mc could be heard. The radio communications during which the ISS crew reported details about the approach, could be fully monitored via NASA-TV. The approach took place automatically with the system Kurs followed by the docking (soft mate) at 0510UTC.

During the pass in ISS orbit nr. 48557, 0605-0615UTC Yurchikhin via VHF-1 (143.625 mc) was in contact with TsUP-Moscow and reported that they already had opened the hatch at their side. Air pressure checks were in progress.

On 31 May 2007 Yurchikhin and Kotov made their 1st EVA. Partly this EVA could be monitored via NASA-TV. At the end of the EVA, during their ingress in the airlock, it could be heard how the cosmonauts did air pressure checks before returning into the ISS.

Already on 6 June 2007 Yurchikhin and Kotov made their 2nd EVA. For the greater part the communications during this operation could be monitored via NASA-TV. The conversations at the end of this EVA took place via VHF-1 and could be monitored in Europe between 2040 and 2049UTC.

Serious computer problems in Russian segment of the ISS:

In the night from 11 until 12 June, during the period that Atlantis on mission STS-117 was docked to the ISS, a number of computer systems in the Russian segment failed. Some of them were crucial links in the attitude control of the whole complex and others had functions for other systems such as the oxygen generator Elektron. The failures of the computers had something to do with the transition of a part of the power supply after the link up of new American solar panels for the power supply of the complex.

Yurchikhin and Kotov for hours struggled to reactivate the computers. Now and then they succeeded, but after a while they failed again.

In the first days the Russians regularly checked the by TsUP-Moscow uplinked six figure groups, the so called ‘ugli posadki’. (The angles of attack at certain times the descent apparatus of the Soyuz must enter into the Earth’s atmosphere in case of an emergency return.)

During the whole period of the combined flight of Atlantis and the ISS the radio communications, especially via NASA-TV, were very dense and exciting. Now and then some communication sessions took place at the same time and it was a mixture of different links. During the same relays you could hear the astronauts during an EVA and Yurchikhin and Kotov struggling with their main computers.

Every time they spoke about the problems with the Central computers they used the abbreviation Ts.V.M. followed by a number. It made me think of the frequently failing attitude control system S.U.D. in the MIR station years ago. Often this was followed by the failure of the then used on board computer, also named Ts.V.M. Sometimes I characterized this system as a very sensitive plant, touch-me-not.

The failure of MIR’s attitude control system often had been caused by a change or disturbance in the configuration of the complex. This time now and then this possible cause of the failureon ISS was mentioned and thusfar certainly not excluded. In discussions experts spoke about the over-sensitivity of the on board computers in the Russian segment of the ISS. Sunny Williams spent a lot of time analysing the noise level on the voltage of the American power supply. Experts excluded this possibility as a cause of the failure.

Yurchikhin and Kotov could be heard regularly when they reported about their inspections and procedures. Meanwhile they discovered some little deviations in the power supply systems, but sofar there has not been published a definitive conclusion of the real cause of the problem.

Presently the main computers in the Russian segment function normally again, but this was not so with the reserve systems. Radio conversations revealed that during tests these systems frequently failed. This is one of the reasons that the decision was taken to send new computers to the ISS with the freighter Progress-M61. It has been established that the gyroscopes were not involved but nevertheless a replacement gyroscope will be delivered to the ISS by the next shuttle flight (STS-118).

For ESA the computer topic is very important because the computers installed in the Russian segment are partly equal to the systems which will be used in the ATV (the European freighter) and the module Columbus.

The necessity to send by Progress-M61 new computer systems caused some changes in the planned launch date of that ship. Originally the launch was on schedule for 6 August, but this was put forward because of the urgency to 23 July. This was not possible and now the plan is to launch Progress-M61 on 2 August 2007.

Chris van den Berg, NL-9165