BASE jumper

An interesting walk, the events of which unfolded over an hour.  Over this time I was, on and off, thinking about what the slightly out of place vehicle and the two people with the cuboid back pack (and the thing that looked, at some distance, like a kettle) were up to - scientists doing field work?  On my way back, one of the people was gazing upwards.  Birders?  I was going over to ask.  I couldn't see the second person and then spotted her/him on the platform of the mast.  Just had time to think that it was a bit odd having the person on the ground where they were, when the person on the platform climbed over the railings and jumped..........