A mysterious balloon from China, called a spy device, has been shot down. If it's really a spy balloon, what kind of ability?
We quoted from The Conversation, Tuesday (7/2/2023) the following explanation from Ian Boyd, an aerospace expert from the University of Colorado:
What is a spy balloon?
Spy balloons are gas-filled balloons that fly in the sky, at about the same height as commercial airplanes. It has several advanced camera and imaging technologies, and points its instruments at the ground. So, it collects information through photography and other imaging than what happens on land.
Why choose a spy balloon over a satellite?
There are two types of satellites based on their orbits. The first is a low-orbit satellite, where it is quite close to the ground, even though it is still hundreds of kilometers above. The surplus, he can snap clearer pictures.
But the drawback is that this satellite continues to circle the Earth, where one orbit takes only about 90 minutes. So the results of the photo can be less clear because of the fast movement.
The second type of satellite is a satellite with a geosynchronous orbit which is located even higher. Then the resulting image may be more or less clear. But in excess, the satellite can monitor the same area because it moves the same as the rotation of the Earth.
Well, spy balloons can be much closer to Earth so that the photos obtained can be clearer. Not only that, the movement is relatively slow. But the drawback, this balloon can be seen clearly so it's easy to target. Then, less can be fully controlled.
What photos can a spy balloon take?
It is not yet known what reconnaissance technology is in the balloon from China. It could be that he has some kind of camera. Satellites or spy planes sometimes take ordinary photos, with very good zoom capabilities to be able to enlarge the resulting photos.
But different types of information can also be collected in other parts of the electromagnetic spectrum, for example by infrared. If it's night, a camera operating in the visible part of the spectrum will show nothing but darkness. But infrared cameras can catch something from heat in the dark.
How is the spy balloon steered?
Most of these balloons move with the wind. There may be a bit of navigation, but you can be sure there's no one in it. They depend on weather conditions.
Sometimes there are guide devices that change the height of the balloon to catch the wind in a certain direction. According to reports, the Chinese reconnaissance balloon has a propeller to help steer it. If true, it means the operator will have more control over the balloon's path.
There is an internationally accepted boundary called the Karman Line at 62 miles (100 kilometers) elevation, where anyone can operate anything. But the balloon is well below that altitude, so it's actually in US airspace.
How many countries operate it?
It seems rare for a country to actively use spy balloons these days. The US flew many balloons over the Soviet Union in the 1940s and 1950s, and they were eventually replaced by the U-2 spy plane, then replaced by satellites.
The balloon poses no real threat to the US. Maybe China is just experimenting where the balloon isn't very advanced technology. Maybe China wants to send a certain message.