The ESA POCKET compression algorithm for satellites housekeeping telemetry

Abstract

The European Space Agency (ESA) and its European industry partners generate every year many new and innovative ideas for advancing European space technology regarding mission operations. On this basis, arises the idea of designing the ESA POCKET compression algorithm for satellites housekeeping telemetry, intended to be one of the experiments that will be validated in the OPS-SAT Mission. OPS-SAT is the first CubeSat designed by ESA, providing a low cost in-orbit laboratory available for authorised experimenters to test, demonstrate and validate their development software experiments. It will be available for experimenters wishing to test and demonstrate new software and mission operation concepts such as the ESA POCKET compression algorithm. ESA POCKET is a new method for compressing packets in real-time i.e. each individual packet is compressed into an equivalent smaller packet as soon as it is generated. This cannot be done by compression algorithms such as ZIP, since they require a critical number of packets to be stored before the compression algorithm can be effective. ESA POCKET is designed to be a software plug-in that is added just after each packet is generated. Another software plug-in is added just before the mission control system to intercept the compressed packets and expand them before arriving to the operators, to whom the disturbance is minimal since they do not notice it at all and thus all normal operations concepts can be applied. ESA POCKET aims at using compression to reduce the bandwidth consumed by housekeeping data, which can then be used instead for additional science data or for saving memory space, downlink time and downlink power. Thus, this opens up the possibility of increasing the information content. Moreover, as it works on single packets it can be applied only when needed, introducing much more flexibility into this chain and therefore, reducing preparation and operations costs. Besides OPS-SAT, for all its advantages and the successful performance results, ESA POCKET has been selected to fly also on the ESA Mission Proba-3 and it considered as well for the TIA Mission Electra and for future UAV control systems.