In the far upper left corner of the first picture...
...that ghostly silvery oval floating in a pale sky...
...is that a UFO monitoring the activity of the men working below?
What gave it away was the guys in the clean suits, I figured they
were probably in a clean room, assembling a spacecraft (it didn't
look like a biotech lab). When you gave the clue it clinched it.
The only thing that puzzled me were those gadgets on tripods looking
like theodolites or surveyor's transits.