“Balloons”: Underrated tech and scouts

　　In the public perception, previous understanding of balloons may be limited to hot air balloons with limited flying height and distance. Now people suddenly realize that a “wandering balloon” can fly tens of thousands of kilometers at an altitude of more than 30,000 meters, avoiding modern radar and other high-tech reconnaissance methods, and even making the world’s most advanced fighter jets helpless.
　　On the evening of February 3, 2023, a news about “Chinese balloon strayed into US airspace” became a trending search. No one expected that a balloon from China would cause an uproar in the United States thousands of miles away.
　　 In this regard, the spokesperson of the Chinese Ministry of Foreign Affairs responded: “The airship is from China and is of a civilian nature. I regret that I strayed into the United States. China will continue to maintain communication with the United States and properly handle this unexpected situation caused by force majeure.”
　　 In the public perception, the past understanding of balloons may be limited to hot air balloons with limited flight heights and distances . Now people suddenly realize that a “wandering balloon” can fly tens of thousands of kilometers at an altitude of more than 30,000 meters, avoiding modern radar and other high-tech reconnaissance methods, and even making the world’s most advanced fighter jets helpless.
　　 Generally speaking, the higher the altitude, the thinner the air. Under the pressure difference between inside and outside, some hot air balloons will inflate and explode after rising to a certain height. How can such a fragile balloon rise to thousands of miles and cross the ocean?
　　
　　”Science and Technology Journey” Across the Ocean
　　 In the 1960s, large non-inflatable film plastic balloons were widely used, and some developed countries in the world began to develop high-altitude balloon technology on a large scale. In atmospheric and space science research, balloons began to keep pace with rockets, artificial satellites and other aircraft.
　　 The data shows that the spheres of high-altitude balloons are mostly made of high-pressure polyethylene material through hot-press welding, and their low-temperature performance and tensile strength are very good. In order to improve the load-bearing capacity, the large balloon is also equipped with nylon reinforcement along its generatrix. The shape of the sphere is mostly natural, and the so-called zero-pressure type is adopted, that is, an exhaust pipe is left in the lower part of the sphere to connect the inside and the outside, and the pressure difference is zero, which is used to prevent the balloon from bursting due to the increase in internal pressure after the balloon is lifted into the air.
　　 On the evening of August 27, 1978, a huge silver balloon slowly landed near the small town of Muret in northwest France. A red and yellow gondola with bright colors hangs below the balloon. After 6 days and 6 nights of flying, the balloon named “Double Eagle II” flew all the way from the coast of Maine, the United States, across the Atlantic Ocean, and arrived in Normandy, which is close to the English Channel. crossing the Atlantic” dream.
　　 In the following 30 years, flying balloons developed rapidly. In January 2015, a helium balloon also named “Double Eagle” successfully flew across the Pacific Ocean again, and set two world records for the longest flight distance and longest duration of a balloon flight.
　　 “Go wandering” across the ocean is just a footnote in the history of hot air balloon development. During this journey, the balloons that were gradually used by civilian and even military purposes completed their transformation and became an indispensable member of atmospheric and space science research. Weather balloons are one of them.
　　
　　The sounding height reaches nearly 50,000 meters.
　　 The weather balloon is an observation platform made of rubber or plastic and filled with gases lighter than air such as hydrogen and helium. For example, a weather balloon is like a “CT scanner”, which sends data such as temperature, air pressure, air humidity, wind direction and speed at different altitudes and longitudes and latitudes back to the ground through signals to obtain key meteorological element values.
　　 In 1999, the Latex Industry Research Institute of the Ministry of Chemical Industry became one of the first batch of transformed technology companies in China, and changed its name to China Chemical Industry Zhuzhou Rubber Research and Design Institute Co., Ltd. (referred to as Zhuzhou Rubber Institute). Since then, it has started to build a production line for medical butyl rubber stoppers. Due to poor management in the early stage and drastic market changes, Zhuzhou Rubber Institute, which was on the verge of bankruptcy, stopped the project in 2003 and turned to research and development of sounding balloons.
　　 According to public information, at present, Zhuzhou Rubber Institute has mastered two balloon production processes: dipping method and rotational molding method. The product category ranges from 10 grams to 5,000 grams, and the sounding height has reached 48,000 meters.
　　 What is the concept of 48000 meters? According to data, the flight altitude of civil aircraft is generally 6,000 to 9,600 meters for short routes, and 8,000 to 12,600 meters for long routes.
　　The “scout” that cannot be ignored is
　　 not only used for scientific research and exploration, but also for military use in history because the flying altitude is high enough. In addition to playing a role in reconnaissance, surveillance, communication, relay, and transportation, military balloons are also used in research on rocket launches and UAV swarm delivery.
　　 Among the many research countries, the United States is very familiar with the research of military balloons. For a long time, Western countries have used balloons for battlefield reconnaissance. By the early days of the Cold War, balloons had become an essential part of the espionage game.
　　 According to records, the United States once produced a “spy balloon” for the Soviet Union. It is huge in size, with a diameter of nearly 40 meters. The hanging basket is equipped with advanced cameras and positioning systems, which can take pictures and reconnaissance of the Soviet Union at an altitude of 18,000 meters. But because the balloon will “follow the wind”, it is difficult to control, and in the end it has little effect.
　　 So far, high-altitude balloons are still the focus of American research. It has been reported that “the U.S. Pentagon has significantly increased the budget for high-altitude balloons, hoping that they can help track and intercept Russian and Chinese hypersonic missiles.” According to a report in Fortune magazine: “Compared with previous military airships, the United States High-altitude balloons have higher technological content.”
　　 In early May 1974, a high-altitude reconnaissance balloon entered China and floated towards Bohai Bay. This reconnaissance balloon is equipped with a high-definition camera, which can clearly capture ground images at an altitude of 10,000 meters to 20,000 meters, and transmit them back to the United States with wireless equipment. On May 15 of that year, two J-6 fighter jets shot down the balloon.
　　 The United States, which is used to using high-altitude balloons for reconnaissance, is not surprising that it is so nervous about the yaw Chinese civilian airship this time.