Introduction
Spacecraft Operations comprises an interdisciplinary subsystem, responsible for ground mission control, implementation of Telecommand and Telemetry services, automation of nominal pass procedures, operating as the “command centre” of spacecraft’s on-board applications actualized through the ground infrastructure.
In parallel, Space Operations are in charge of preparing rigorous mission planning, namely mission timelines and phases, complemented by the design of the spacecraft’s functional architecture, the Operational Modes.
Mission control tools are also utilized to mitigate functional outage risks and prepare future operators for in-orbit troubleshooting. Inclusively Space Operations is a collection of activities aiming to realize the prime goal of maximized mission return while guaranteeing operational robustness.
Phases & Modes
Actualization of Mission planning constitutes one of the most fundamental tasks of Operators. One aspect is the delineation of Mission Phases, before, during and after mission.
Mission Phases can be divided in 6 operational intervals, such as preparation, commissioning, operational and post mission phase. Each stage describes the fundamental events and actions needed to be performed in order to successfully complete the mission objectives.
Additionally, operators contribute to the development of system modes, which depict the different operational actions performed during distinct spacecraft situations. Transition between modes can be actuated via automated and manual processes while each transition is defined by specific parameters, exit and entry triggers, that need to be met.
Timelines
Every activity, from the launch preparation until the end-of-life of AcubeSAT, needs to be planned beforehand and be presented on a high-level timeline. The timelines can be split into the Activation Sequence and the Nominal Sequence.
The former refers to all activities between the ground station and the satellite until the first Acquisition of Signal and the latter refers to all operational activities, from that moment until the end of life.
Procedures
During a mission, it is important to always follow particular steps when dealing with a problem or non-nominal situation.
In order to do that, the operations team must have considered all the possible events that could happen and lead to negative consequences for the satellite, and therefore, the whole mission.
Operational procedures include plans and courses of action related to the above that will be included in the operations manual of the spacecraft.
Operability/Adaptability
Many operational aspects are taken into account while designing the functional architecture of the satellite. The subsystem takes place in the evaluation of the Packet Utilization Standard Services (PUS) that will be used from the CubeSat.
Those services describe the application layer of the satellite and they are of great importance to the operator as they indicate which functions can be performed from the satellite and how. Some examples of those services are time scheduling – used for scheduling activities based on time -, the memory management and the housekeeping -for monitoring important parameters.
Mission Control
Τhe subsystem aims to configure and develop the mission control interface as well as to implement the mission’s operational database. The Yamcs mission control interface is selected as the current primary tool to manage the received Telemetry and send the appropriate Telecommands to control the AcubeSAT. Furthermore, the Ground Station will be part of the SatNOGS network, thus the Telemetry can be monitored via the SatNOGS network.
Mission Database
In order for the mission control to be actualized, a mission database is formed.
It contains all the parameters and Telecommands that will be utilized for the proper communication of the ground station with the satellite. This database is currently preliminary and will be finalized during the D1 phase of the FYS!3 programme.
