Doing a search on it, there is very little non-Microsoft stuff, but this one looks interesting:

https://element84.com/geospatial/how-microsofts-planetary-computer-uses-stac/

“Microsoft launched the Planetary Computer in April 2021, and since then Element 84 and others have worked with Microsoft to help maintain and improve the system. The Planetary Computer provides open access to petabytes of cloud-optimized geospatial data, and is built on the STAC specification and the open system of tools around that specification. In this post, we’ll walk through the components of the Planetary Computer and show how it is based on both cloud-optimized formats and the STAC spec, and how this work benefits the larger community.

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