 Its role was to provide satellite control for the European Space Research Organisation (ESRO), which is today known as its successor organisation, the European Space Agency (ESA).The 90-person ESOC facility was, as it is today, located on the west side of Darmstadt; it employed the staff and resources previously allocated to the European Space Data Centre (ESDAC), which had been established in 1963 to conduct orbit calculations.These were augmented by mission control staff transferred from ESTEC to operate satellites and manage the ESTRACK tracking station network.