WRC-19 agenda items related to space science and Earth observation

*This article was originally published in the recent ITU News Magazine edition “Managing spectrum for evolving technologies.” Any views expressed in this article do not necessarily reflect those of ITU.

Among the space science services are the Earth exploration-satellite and meteorological-satellite services, including systems for passive and active remote sensing of the Earth and its atmosphere. These radio services enable us to obtain important data about the Earth and its atmosphere. Also, the space research and space operation services are used by the world’s civil space agencies to explore and work in space. These include robotic missions to other planets and objects in space along with the human exploration of space, the Moon, and beyond.

At a recent meeting of the Space Frequency Coordination Group (SFCG), various plans for lunar exploration were discussed including lunar missions from the United States, the European Space Agency (ESA), India, the Republic of Korea, China, Japan and Russia, among others. Access to and protection of the radio spectrum for these uses is critical to understanding the future of our planet and to all aspects of space exploration.

Related: Read the latest ITU News Magazine here

WRC‑19 agenda items directly related to space science/meteorology

There are three WRC‑19 agenda items directly related to space science and meteorology.

Agenda item 1.2 — frequency bands 401–403 MHz and 399.9–400.05 MHz

Agenda item 1.2 deals with in-band power limits for earth stations operating in the mobile-satellite service, meteorological-satellite service and Earth exploration-satellite service in the frequency bands 401–403 MHz and 399.9–400.05 MHz. This agenda item is a result of the recent significant increase in the use of these frequency bands for telemetry, tracking and command (TT&C) purposes.

The proliferation of such TT&C usage poses a potentially significant impact on the large number of existing lower power data collection system (DCS) stations communicating to sensitive receivers on GSO and non-GSO (NGSO) satellites.

 Access to and protection of the radio spectrum for these uses is critical to understanding the future of our planet and to all aspects of space exploration.

Tens of thousands of DCS stations are deployed worldwide for collecting essential weather and climate data on small platforms such as ocean buoys. If the use of these bands for TT&C is not limited in some manner, the bands will become unusable by these low power DCS systems. Therefore, in-band power limits are needed to protect these DCS stations while allowing these small satellites to operate as well.

Agenda item 1.3 — frequency band 460–470 MHz

Agenda item 1.3 considers the possible upgrade of the secondary allocation to the meteorological-satellite service (space-to-Earth) to primary status and a possible primary allocation to the Earth exploration-satellite service (space-to-Earth) in the frequency band 460–470 MHz. In order to provide for primary allocations in this band for space services, an appropriate power flux density (PFD) mask is needed for the space-to-Earth transmissions to protect the existing terrestrial users. These meteorological satellites are currently used for DCS downlink transmissions but on a non-interference, unprotected basis. Similarly, a number of small Earth-observation satellites have been using this band to downlink scientific data. The PFD mask derived by the ITU Radiocommunication Sector (ITU–R) studies will enable these systems to operate while protecting the terrestrial users in the band.

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Agenda item 1.7 — TT&C

Agenda item 1.7 was developed to study the spectrum needs for TT&C in the space operation service for non-GSO satellites with short dura‑ tion missions, to assess the suitability of existing allocations to the space operation service and, if necessary, to consider new allocations in certain portions of the radio spectrum. These NGSO short duration satellites are often small research satellites developed and operated by educational and scientific entities. There is currently limited spectrum available for their TT&aC operations. Possible methods to satisfy this agenda item would provide possible solutions to this problem.

WRC‑19 agenda items that may negatively impact space science/ Earth observation

There are several WRC‑19 agenda items that are of concern to the space science and Earth observation operators due to the possibility of negative impacts to these missions.

Agenda item 1.6 — NGSO fixed-satellite service

Agenda item 1.6 considers the development of a regulatory framework for NGSO fixed-satellite service (FSS) systems in certain bands between 37.5 and 51.4 GHz. Two of those frequency bands, 47.2–50.2 GHz and 50.4–51.4 GHz, for uplink transmissions are immediately adjacent to either side of the 50.2–50.4 GHz passive Earth observation band which is critical as a calibration window to measurements of atmospheric temperature.

The current limits in Resolution 750 (Rev. WRC‑15) need to be properly revised to protect these important Earth observation functions from the aggregate interference from out-of-band emissions of both GSO and NGSO FSS systems.

Agenda item 1.13 — International Mobile Telecommunications

Agenda item 1.13 considers the identification of frequency bands for the future development of International Mobile Telecommunications (IMT), including possible additional allocations to the mobile service on a primary basis for this purpose in various bands from 24.25 to 86 GHz.

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For space science operators, the main concern is protecting existing earth stations operating in 25.5–27 GHz for both Earth observation and space research downlinks and ensuring the operation of future receiving earth stations in this band.

The second issue involves the protection of certain critical Earth observation passive sensing bands, such as 23.6–24 GHz, 31.3–31.8 GHz, 50.2–50.4 GHz, 52.6–54.25 GHz, and 86–92 GHz. The protection of these bands from aggregate interference from out-of-band emissions from future IMT deployments is critical as many of these bands are used to obtain measurements on a global basis that cannot be made in any other way.

Agenda item 1.14 — high-altitude platform stations

Agenda item 1.14 considers appropriate regu‑ latory actions for high-altitude platform stations (HAPS) within existing fixed service allocations. It should be noted that HAPS downlinks will have a more severe impact to space science receiv‑ ing earth stations than HAPS uplinks. However, HAPS uplinks may have potential impact on adjacent band passive Earth observation sensor operations. Care must be taken to ensure the protection of these earth stations and Earthobservation sensors.

Agenda item 1.15 — land-mobile and fixed services

Finally, agenda item 1.15 considers identification of frequency bands for use by administrations for the land-mobile and fixed service applications operating in the frequency range 275–450 GHz. Currently, there are several bands that are being used by Earth observation systems in this frequency range.

Currently, there are two items on the preliminary agenda for the World Radiocommunication Conference 2023 (WRC‑23) that are directly related to the space science and Earth observation areas.

Studies have indicated that except for the bands 296–306 GHz, 313–318 GHz and 333–356 GHz, the rest of this frequency range could be identified for use by fixed and land mobile operations while still protecting these Earth observation passive sensors.

Possible WRC‑23 agenda items for space science and Earth observation

Currently, there are two items on the preliminary agenda for the World Radiocommunication Conference 2023 (WRC‑23) that are directly related to the space science and Earth observation areas.

The first is agenda item 2.2, concerning a possible new allocation to the Earth exploration-satellite (active) service for spaceborne radar sounders within the range of frequencies around 45 MHz. This new application of Earth observation could enable the location of subsurface water from Earth orbit as well as measurements of ice thickness in the Polar Regions.

The second, agenda item 2.3, concerns space weather sensors, and the possibility of provid‑ ing appropriate recognition and protection in the Radio Regulations for this important area of study. Space weather observations and study of the solar-terrestrial relationships have evolved from exploratory to operational as countries monitor solar flares and geomagnetic storms and their possible impact on life on Earth. The time has come to consider some sort of regulatory recognition of this important aspect of space and terrestrial science.

Other possible agenda items for WRC‑23 being discussed in various regional groups that are related to space science and Earth observation are such things as a possible new allocation for the Earth exploration-satellite service in 22.55– 23.15 GHz; radiocommunications for sub-orbital vehicles; a possible upgrade of the allocation of the band 14.8–15.35 GHz to the space research service; and, the consideration of possible adjust‑ ments to passive remote sensing allocations between 231.5 and 252 GHz.