Saw an interesting story that lead me to something even more interesting:
Story: A Dozen Mystery Objects Suddenly Popped Out Of Hangars At Tonopah Test Range Airport
Well, apparently they used a service here: https://www.planet.com/ which has a 14-day trial / subscription service: https://www.planet.com/products/planet-imagery/
Wouldn't it be interesting to get such a subscription to not only be able to watch for things at points of interest, but also to run this through an diff'ing algorithm that would then watch for particular changes that were non day/night oriented or specifically seasonal? Hmmm. It could be done!