Happy birthday, Nny!
Soaring through the middle atmosphere with the sun on your backs and the glint of one another's wingtips flickering at the edge of your vision, you slowly spiral down toward the lower atmosphere and the surface. It's formation flying at its best, and a very pleasant way to balance filling the duty roster and celebrating a birthday. The planet needed surveying anyway -- Especially that very regular round lake down there. It's probably a crater. There are several like it nearby. None of the others, though, have radio signals coming from them.
The radio signals are getting stronger as you get closer, too. They're interfering with your helmet coms, more's the pity; you're getting a lot of static. It's an odd sort of static, too: it comes in stacatto bursts, and seems to be interspersed with bird screams. They might be bird screams: some big birdlike creatures are soaring around you.
There are islands on the crater lake, little regular square islands. They're moving, drawing together. Suddenly
You take it from there.