Retire the spacecraft, preserve the record

Meteosat-7’s final image scan was on March 31, 2017. EUMETSAT sent its final command on April 11 after end-of-life maneuvers moved the spacecraft away from the protected geostationary region. These are separate events: the last weather observation, disposal maneuvers and spacecraft shutdown should not be collapsed into one unlabeled date.

A graveyard orbit is an orbital relocation, not a claim that the spacecraft has reentered Earth’s atmosphere. Meteosat-7’s end-of-life work used its remaining propellant and turned off its instruments. An original retirement timeline should identify each objective and the evidence for completing it, rather than treating “retired” as a complete technical description.

Ending transmissions does not erase the observations already preserved. EUMETSAT produces climate data records from current and past satellites, including first-generation Meteosat visible and infrared measurements. Such records require calibration, consistency and quality information; a long folder of image files is not automatically a reliable climate series.

Consider an original two-instrument example: both view the same stable target, but the replacement sensor reads slightly higher. If that difference is ignored, the combined record may appear to jump when the satellite changes. Overlap, calibration information and uncertainty estimates help separate instrument effects from changes in the environment.

Retirement and the record have separate timelines

The 2020 Release 1 user guide for the MVIRI Fundamental Climate Data Record defines the included data and exclusions. It does not claim that every observation from every first-generation mission appears in that release. Program duration, surviving observations and the coverage of a particular processed dataset are different measures.

Before using an original teaching dataset, write down its version, time span, included satellites, quality flags and gaps. Reprocessing may improve the interpretation of an old measurement without making it a new observation. This is how a retired program can continue contributing evidence while the archive remains honest about what the record contains.