Low orbit satellites are closer to the ground, which means they are able to see things more clearly but have to keep moving, Iain Boyd, a professor of aerospace engineering sciences at the University of Colorado, told the Conversation.

Meanwhile, a satellite in geosynchronous orbit is much farther away from Earth’s surface, meaning it can capture images continuously — but not as clearly.

“A balloon in some ways gets the best of those. These balloons are much, much closer to the ground than any of the satellites, so they can see even more clearly,” Boyd writes.

“And then, of course, balloons are moving, but they’re moving relatively slowly, so they also have a degree of persistence.”

[Well, that at least is an answer, but it’s still not terribly explanatory. Read the whole article to get a sense of the perceived value of balloons over satellites, but most of those are really applicable to those in the upper stratosphere — 100,000 feet, not 60,000 feet, where they are more detectable and vulnerable. It still leaves the question: why did China choose balloons traveling in the detectable and targetable altitudes? — Ed]