The International Telecommunication Union (ITU) is the leading United Nations agency for information and communication technology issues and the global focal point for governments and the private sector in developing networks and services. The Radiocommunication Sector of the ITU (ITU-R) plays a vital role in the global management of the radio-frequency spectrum – a limited natural resource which is increasingly in demand from a large and growing number of services including science services such as the Earth Exploration-Satellite Service (EESS). The EESS makes use of specific frequency allocations as documented in the ITU Radio Regulations (RR). Use of EESS frequency allocations is further refined in the RS Series (for remote sensing) and the SA Series (for space applications, in particular for data communications to and from science satellites) of the ITU-R Recommendations, based on technical characteristics and operational procedures.