“Balloons go with the wind. And so the only control that a balloon has is: in some balloons, you can control the altitude—you can make it go higher or lower. To the extent that the wind speed and direction varies with altitude, you can change the altitude, within some limits. And that can give you some measure of control—but not anywhere near the level of control that you have [with an airplane]. You can’t turn around and go the other direction; you can never go upwind in the balloon. You’re always going to be moving with the atmosphere that surrounds it.”
“A balloon is not a particularly good platform for a couple of reasons. One is that you can’t steer it”
Spy balloons do some advantages over satellites; they are relatively inexpensive and can be more maneuverable. So it’s obviously worthwhile for the US military to continue to scan the skies looking for strange objects that might be Chinese balloons or spy drones.
The balloon is not going to run out of fuel, since it has solar panels. The official also said that the balloon steers by rudder and is corkscrewing around to slow its progress over land, but the jet stream continues to move it on a trajectory across the U.S. The Pentagon is still considering ways to “dispose” of it but has “grave concerns” about the damage it could cause if it fell to Earth.
"…surveillance device outfitted with a suite of sensors and a camera sensitive enough to detect people standing on the ground from the edge of space. The stratollite travels by virtue of two balloons, one filled with helium to provide lift, and the other with pressurized air, which functions as a steering system.