NASA remote sensing missions and frequency issues

The NASA Office of Earth Science has three uses for the radio spectrum: to probe the Earth and its atmosphere by transmitting radio signals and observing their return, to observe the natural emissions from the Earth and its atmosphere, and to communicate with its satellites. NASA follows the spectrum allocations in the Radio Regulations issued by the International Telecommunications Union (ITU). The ITU divides the radio spectrum into bands allocated to specific services. Most bands are shared among several compatible services. A primary allocation grants equal footing with other users of a band; whenever interference exists, band users must coordinate among themselves. A secondary allocation allows operation as long as primary users do not suffer interference; conversely, secondary users have no protection from interference caused by primary users. Footnotes in the radio regulations indicate minor additions and exceptions. They may include notices of unusual (e.g., scientific) band usage. Such footnotes are generally honored. Changes in the Radio Regulations are made at World Radiocommunications Conferences (WRCs) held every few years, or as needed. Obtaining and maintaining these levels of protection require constant vigilance on the parts of NASA and the science community. Each of the above three uses of the radio spectrum are discussed.