Align fields with STAC specification?

[weiji14]

Just got some great ideas after attending this Cloud-Native Geospatial Event (https://schedule.cloudnativegeo.org) and learned a lot about Spatial Temporal Asset Catalogs (STAC) and OGC API standards! So the people working on those standards have literarlly spent years thinking about metadata, and these are some relevant ones that popped up from scanning through https://github.com/stac-extensions/stac-extensions.github.io:

• Satellite - https://github.com/stac-extensions/sat
• Synthetic Aperture Radar (SAR) - https://github.com/stac-extensions/sar
• Hyperspectral imagery - https://github.com/stac-extensions/hsi

It seems like there are some required fields/attributes which we could definitely ensure are present in our database. Using Sentinel-1 (a SAR satellite) as an example, frequency_band is required, and there's a list of Common Frequency Band Names to select from. See their example sentinel-1.json vs our current Sentinel-1.json