Balloon affair – search for clues: a weather balloon or espionage? – Knowledge

A stratospheric balloon causes a stir and diplomatic tensions between China and the USA. The balloon flew over several states in the northern United States before the US Air Force shot it down over the Atlantic.

The search for the wreckage of the balloon has begun. The US government reports that the first results would prove that it was clearly a spy balloon. China’s position is that the balloon only collected weather data. A search for clues by science journalist Cathrin Caprez.

Catherine Caprez

Science Editor SRF

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Cathrin Caprez studied chemistry and worked in chemical analysis for several years. She has been working as a science editor at SRF since 2016.

What could be seen in videos and photos of the controversial balloon?

In addition to all the unanswered questions, one thing is certain: the balloon was very big. Its diameter was between 25 and 30 meters. The entire vehicle could have been a good 60 meters high. Normally, such weather balloons have a diameter of only about 15 meters in height.

What can such normal weather balloons carry with them?

MeteoSuisse releases a weather balloon twice a day. For such a standard flight, the balloons are equipped with a small radio probe including GPS, which measures air pressure, temperature and humidity and continuously sends the data to the ground station. This probe is slightly larger than a pack of cigarettes.

In addition, the meteorologists can also send up special devices with the balloon, for example to measure ozone. Or cameras for recordings. Even for that, a balloon doesn’t have to be nearly as big as the Chinese example.

Does the flight altitude of the aircraft indicate which mission it was on?

The balloon was basically deeper and much longer than weather balloons usually are. These usually rise from one point through the layers of the earth’s atmosphere up to about 35 kilometers. There the balloon bursts and the measuring devices usually sink back towards the ground on a small parachute. The whole thing takes about three to four hours.

The Chinese balloon, on the other hand, traveled for days at a height of between 18 and 20 kilometers. Maybe he got stuck at this height, so to speak. This can also happen with an ordinary weather balloon. For example, if he has a leak in the envelope of the balloon. But for several days – that’s unusual.

Satellites provide us with high-resolution data from space around the clock – in comparison, a weather balloon like this has something almost archaic about it. Are they used often?

yes they will They have certain advantages over satellites: They provide high-resolution measurement data, are significantly cheaper – and because they have been in use for so long, they are also important for climate research today.

What is the conclusion: was it just a weather balloon or was it a spy balloon?

That cannot be said with certainty. For a weather balloon, it would definitely have been a very unusual, but perhaps also simply new type of balloon. He would certainly have gone astray, because the great advantage of weather balloons is precise altitude profiles and not measurements over such long distances.

Perhaps examining the wreckage will reveal more. But because the incident is so politically charged, there may never be complete clarity about the true purpose of the balloon.

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