Was the Chinese balloon indeed a spy at work or was it just hot air?

Balloons are 18th century tech; Chinese satellites allow for surveillance with far higher levels of efficiency

The so-called China spy balloon matter has caused a diplomatic crisis with the US Secretary of State pulling out of a scheduled high-level visit to Beijing, while the Chinese government has vowed to give an “appropriate response” to the downing of the balloon off the Atlantic coast.

However, the incident itself has multiple puzzling factors. As far as one can figure, a Chinese balloon was spotted crossing the Pacific Ocean, and arriving in Alaska (on the North West coast of the US) and then crossing the entire breadth of the North American continent, including overflying Canada before it headed South after reaching the Atlantic coast. It was shot down and landed somewhere in the Atlantic Ocean where the US navy is now trying to retrieve it.

The Chinese insist that it was a “civilian airship which had limited self-steering capacity”, while the US shot it down after it overflew some sensitive areas. The Pentagon publicly assessed the balloon as a very minor threat and also claimed that three similar balloons had crossed into American airspace during the Trump era (2016-20) without any action being taken. Another similar balloon is said to be overflying Latin America at the moment.

The puzzle is as follows.

Balloons are literally 18th century technology though the 21st century versions may be more sophisticated. When it comes to surveillance, China has proven capability in terms of its grasp of highly sophisticated satellite technology, which is capable of conducting surveillance with far higher levels of efficiency. Why would it use balloons?

Many countries do use balloons for weather monitoring purposes and also for scientific research in the atmosphere.

Starting late 18th century, balloons were used as observation posts during military conflicts. During the First World War, artillery units were using manned balloons as observation posts, and motorised rigid airships such as the Zeppelins were also being used as bombers. Until late into World War II, balloons were also tethered around potential targets to make it more difficult for enemy aircraft to carry out aerial attacks.

The modern balloon as used in weather research or surveillance is a high-altitude vehicle, which climbs up to anywhere between 20,000 metres and 35,000 metres. The record height is over 50,000 metres. The average civil airliner flies at 12,000 metres and most military aircraft have “ceilings” of around 20,000 metres. So balloons are unlikely to cause accidents.

They can be very large or quite small, ranging in size from a 1,000-litre tank to the size of “three football fields” in this particular case. They are usually unmanned and carry a payload of scientific instruments for sampling air composition, ambient temperature, figuring out wind currents, ultraviolet radiation, etc.

Balloons are filled with either helium or hydrogen gas to give them lift. If they don’t have motors (the Chinese description of an airship suggests this specimen may have been motorised but that could be a mistranslation), they are more or less at the mercy of wind currents, though they can go up or down by changing the ratios of gas and ballast used for buoyancy.

The advantages are: balloons are relatively cheap (than satellites); they can stay up indefinitely without expending any energy for mobility, though of course, scientific payloads and communication systems require energy; and they can deploy solar panels to top up.

A balloon the size of this one could have a pretty large array of instruments. The path of this balloon does suggest it was launched into a “Westerly” air current, as the Chinese claim, and floated out over the North American continent due to that reason. This doesn’t rule out the fact that it may have been done deliberately, though the Chinese say it was “force majeure”.

Balloons can loiter indefinitely over specific areas, depending on the air currents. They are much closer to the Earth’s surface than satellites, which orbit hundreds of km above the Earth and move very quickly (unless they are geostationary). So, balloons can probably pick up more visual detail than satellites, though civilian satellites can easily resolve images down to 3-4 cm. Military satellites are classified and may do better, though the laws of physics suggest there are limitations.

However, anybody using a balloon for surveillance would have to balance these advantages off against the lack of control of steering and navigation. Also, balloons are slow-moving objects, which can easily be interdicted or shot down, and their paths are predictable.

India is reportedly switching to using drones rather than weather balloons because drones are easier to steer and move around.

An object this size can also easily be seen with the naked eye – indeed it was, and photographed by many people. So we’re left wondering if this was an accident, or a provocation carried out for inscrutable reasons.

Balloons for surveillance

Advantages

• Relatively cheap (as compared to satellites)
• Can stay up indefinitely without expending energy for mobility (though scientific payloads and communication systems require energy)
• Can deploy solar panels to top up
• Can loiter indefinitely over specific areas
• Much closer to Earth’s surface than satellites, so, can probably pick up more visual detail than satellites, though civilian satellites can easily resolve images down to 3-4 cm

Disadvantages

• Lack of control of steering and navigation
• Slow-moving; can easily be interdicted or shot down
• Their paths are predictable
• Can easily be seen with the naked eye