PRISMA Blog | 16. August 2011 | posted by Ralf Faller

PRISMA Mission Control returned to Sweden

After more than 5 months of successful flight operations by GSOC, the operational control was re-handed over again to the control center in Solna, Sweden. Since handover to GSOC in March this year, various experiments could be performed. My colleagues already reported corresponding details within the Blog. I’ll now try to describe the topic of a satellite mission handover.

The handover of one or more satellites from one control center to the other is a complex process which needs to be prepared thoroughly. The mission safety needs to be ensured and potential risks must be minimized. In general, a mission handover is performed in 3 phases:

1. Preparation phase

The preparation normally takes some months. According to a corresponding handover plan, the required boundary conditions need to be fulfilled. The receiving control center has to pass all tests and simulations successfully in order to get qualified for the flight operations. Technical equipment and personnel must be ready for action. Beyond that, the required data and information and its exchange is to be defined for a smooth handover. These data comprise the latest flight procedures and data bases, configuration information of space and ground segment components etc. When all conditions are fulfilled, details about the handover and the timing are agreed. Therefore a procedure is generated which can be followed during the handover.

In our particular case, the preparations were easier than for the first handover to GSOC some months ago. The Swedish control center was already qualified and a few successful proficiency passes during the last days have confirmed this. Respecting the experiences from the first handover we already knew the relevant aspects for PRISMA and which data and information were needed for s smooth transfer. Thus the previous plan and procedure could be used with some adaptations.

2. Handover execution

The handover itself is only a short step. The providing control center performs the final activities with the satellite and creates the handover data package for the receiver, who in best cases already receives telemetry data which allows following the actions of the others. During a teleconference, the remaining open points are discussed. Finally, both sides agree the formal handover of operational responsibility. The receiving control center will start performing the operations from the next ground station contact on.

For PRISMA we had agreed with Sweden to perform our final activities on 23.08.2011 morning. After the handover teleconference, Solna took over the mission operations with the first afternoon passage over Kiruna ground station. We at GSOC received telemetry in parallel but where no longer actively involved.

3. Standby phase and wrap up activities

After execution of a handover, the providing control center normally stays in standby in order to take over the operations again in case of problems on short notice. The creation of a handover report completes the handover process.

In our case a special standby support was not requested by Sweden since both satellite were returned back to their home control center.

With today’s re-handover of the PRISMA space segment to Sweden, the mission itself is not yet finished for GSOC. One main experiment which could not be performed within the available time frame is still to be done. Negotiations are ongoing if the mission returns back to GSOC for the experiment or if is performed from Solna supported by GSOC personnel.

Fig: Part of PRISMA team

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About the author

Ralf Faller has been a researcher in the Department of Space Operations and Astronaut Training at DLR in Oberpfaffenhofen since 1991. His current responsibilities include robotic space and servicing missions. to authorpage

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