ETRSS: connect national imagery to a lasting data record

ETRSS-1, Ethiopia’s first satellite, launched on 20 December 2019 through cooperation with China. A foreign-ministry account reported its formal handover in December 2020 and described uses in agriculture, forests, water resources and climate-related studies. Launch and handover were separate milestones. The mission also supported experience in receiving and using satellite data, beyond the spacecraft itself.

In a January 2026 interview, the Space Science and Geospatial Institute’s director reported that ETRSS-1 and ET-SMART-RSS had completed their operational lifespans. The same account described ET-RSS2 as a planned December 2026 successor. That date is a plan, not a completed launch in this lesson. The older observations can still be useful after a spacecraft stops making new ones, provided their provenance and quality remain accessible.

Imagine a region has usable images for eight of twelve target months in one year. The observed monthly coverage is two-thirds, about 67 percent. It is not valid to report that all twelve months were directly observed merely because a map is available for the year. An annual summary may combine observations or estimates, and it should explain how missing periods were treated.

Now compare a later year with more complete data. A change in the available months can affect the comparison, especially where vegetation varies seasonally. Compare like periods where possible, or use a method that explicitly addresses the missing observations. This invented example illustrates why a long-lived archive needs timestamps, processing versions and quality flags, not only attractive image previews.

A complete-looking map can hide gaps

A successor can improve measurements while introducing a new instrument response, sampling pattern or processing method. An apparent jump in a time series may therefore reflect a real environmental change, a measurement change or both. If overlapping observations or reference measurements are available, analysts can use them to examine consistency. Without overlap, the limits of the comparison should be stated rather than hidden.

The ETRSS program is consequently about continuity as well as a first launch. Teams need to preserve the earlier record, document what the next instrument measures and keep plans distinct from demonstrated outcomes. A retired spacecraft does not make its entire archive obsolete; a new spacecraft does not automatically make every old and new value directly comparable. Useful national capability includes knowing when the data support a conclusion and when a gap remains.