When it comes to China’s global surveillance efforts over military sites around the world, spy balloons are just as capable of collecting images as a satellite, according to U.S. officials

But balloons can have certain advantages like flying closer to earth, lingering over a site for a longer period and collecting multiple forms of data.

Yoonsuk Choi, Cal State Fullerton associate professor of computer engineering, said taking and collecting images from a balloon at certain altitudes can be easier than using a satellite and better in terms of quality.

Choi said: “Collected images will be much better and the collected data can be processed on a real-time basis. It is also cheaper than using a satellite and way easier to cover certain regions and sites.

“Furthermore, if these were innocent civilian machines as China’s government claims, they would have done it by taking clear and proper steps. The balloons were lingering over some sensitive sites. That proves that they were meant for sneaky surveillance.

“It is possible that there were various sensors on the balloon. Since sensors are very small, they can implement not just a visual image sensor but other sensors like a spectral image sensor. A spectral image sensor along with a visual sensor can do precise target detection and identification. We can even see what's inside a target. For example, it's possible to see what's inside buildings, cargoes and trucks.”