I have some questions what the long term plans of a spy balloon like the US shot down are?
First, they have no measure of propulsion to control their flight, right?
Second, If there are not shot down do they just wander around the Earth aimlessly in the atmosphere until they somehow naturally deflate? Or is there some mechanism for them to self destruct?
Third, any guess any long a balloon would stay aloft in the upper atmosphere?
U.S. officials said they believed that the balloon, outfitted with propellers on the bottom, was able to drift with air currents and be directed. It has changed course on a number of occasions, they said
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Balloons traditionally adjust their boyancy to move up or down where the wind currents can help them get where they want to go. Even without propellors they can be steered somewhat.
I recall reading of a rudimentary use of this with dirigibles. They have those fins on the back - so by adjusting the pressure in the interior air bags, it can be made to sink or rise. That motion, combined with the “wings” (fins) on the back can be used to direct the craft to a certain extent by gliding. Then pump the helium back from the tanks into the bag and rise upward, using the same gliding effect.
No need to scare-quote “wings”. That’s exactly what they are. It’s tough to exactly match zero buoyancy, so they usually run either slightly heavy or slightly light by design, and adjust the wings to maintain level flight via lift.