Shift work in the control room

After we had met in the control room early on Monday – shortly before 02:00 local time – my principal activity was communication with the launch site in Baikonur, exchanging confirmations that everything was still ‘green’ on both sides. As we came ever closer to the planned launch time of 04:14 local time, not only the frequency of the status messages rose, but also our nervousness. Shortly before the launch, we were able to switch to a direct connection with a Russian translator, who performed a live translation of the Russian commentaries from the control bunker for us.

It started 20 minutes before the launch – all systems reported ‘green’ over the live video transmission; we were then able to directly follow the launcher into the blue sky over Baikonur. The successful launch relieved some of the tension! In the meantime, the translator informed us about progress of the first stage, then the second and third stages and finally about the successful separation of TanDEM-X from the upper stage. Now there remained as a last danger only that possibility that the satellite had not survived the stresses of the launch. However, the good feeling that had been with us during the entire launch process did not mislead us, and 15 minutes after separation we received the first signals from the Troll ground station in Antarctica.

The spontaneous jubilation in the control room had to be restrained in order to take care of initial activities such as requesting additional status data and turning on the GPS receiver. After contact, we were even happier, and after extensive mutual congratulations we went back to work.

In the following hours, checkout activities were started – including detailed analysis of the sensors and actuators that are in use at this early stage. The primary focus was on the star trackers, which are used for satellite attitude determination, and the reaction, or momentum, wheels. While the star trackers determine the attitude of the satellite relative to Earth by comparing constellations imaged by their optics with a stored catalogue, the reaction wheels generate the necessary angular momentum change for active attitude control. The greater the rate of change of the rotation speed of a reaction wheel, the greater the torque exerted on the spacecraft.

At 10:00 local time, the first shift – exhausted after a long but successful night – made their way home while the second shift took over.