On the cover, we display one satellite from each GNSS constellation: from foreground to background, GPS, Galileo, GLONASS, and BeiDou. Obtaining authoritative images of GPS and Galileo satellites was easy, of a GLONASS satellite harder, and of a BeiDou satellite extremely hard. I had to consult many experts and try several possible connections to finally obtain one. However, when I did, it was from the horse's mouth: the China Satellite Navigation Office via Prof. Dr. Yamin Dang, Director of the Institute of Geodesy and Geodynamics of the Chinese Academy of Surveying and Mapping. The next challenge was figuring out which constellation was "completed" first: BeiDou-3 or Galileo. China announced last year that the launch on June 23 of its 30th BDS-3 satellite, which was also its 55th BeiDou satellite, marked the completion of its constellation. Europe has not yet made an analogous announcement about Galileo. There is no agreed-upon standard as to when a GNSS constellation achieves full operational capability (FOC), so it is a matter for debate. Essentially, a system achieves FOC status when the service provider says it does. However, it seems clear that BeiDou, with 42 operational satellites, is ahead of Galileo. The order of the satellites in the opening spread for this month's cover story, on pages 20 and 21, reflects that conclusion.
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