New Delhi As a tool for surveillance, the balloon might come across as dated in this age of satellites and drones. Events of the last fortnight, however, appear to have thrown this notion to the wind.
The US shot down what it described as a Chinese “spy balloon” in South Carolina on February 4 (it has now acknowledged that three more objects subsequently shot down could have had a benign purpose). China described the first object as a “civilian airship” used for research that drifted into US airspace.
The balloon’s use for research is well-known, especially in collecting weather-related information. The questions that recent events have raised, however, are about spying. When and where have balloons ever been used for espionage, and does it still make sense in this day and age?
The balloon’s use for spying has been documented as far back as the Napoleonic wars, and as recently as the Cold War. And while modern technology offers superior options, the balloon has certain advantages that a satellite does not.
Flight dynamics
A balloon can be assembled and sent up in a much shorter time than a sophisticated device, and costs much less. It can also capture potentially better images than most satellites can, experts say, besides being relatively easy to send up.
“To put anything into flight, you need to generate lift. Helicopters, drones and aeroplanes generate lift by moving. An aeroplane has to move forward in order to fly; the rotor of a helicopter has to rotate,” said M Ramakrishna, professor of aerospace engineering at IIT-Madras.
“Now, a balloon is like a boat: it floats. It flies simply because it is filled with a gas that’s lighter than air, so there’s no effort you need to put in to make it fly.”
A satellite in orbit typically has to choose between two contrasting aims: image quality and persistence, or the amount of time it spends over one spot. If it flies in low earth orbit, it will capture better images, but its continuous motion will affect persistence. On the other hand, if it flies in geosynchronous orbit replicating the Earth’s path, it will be over the same spot all the time, but the greater distance will affect image quality.
“A balloon in some ways gets the best of those,” Iain Boyd, professor of aerospace engineering at the University of Colorado Boulder, wrote in The Conversation. “These balloons are much, much closer to the ground than any of the satellites, so they can see even more clearly. And then, of course, balloons are moving, but they’re moving relatively slowly, so they also have a degree of persistence.”
The big disadvantage of a balloon is that it is easy to spot and difficult to navigate. “You need to figure out whether you can make it go where you want it to go. Typically, you can have a propeller (the Chinese balloon is said to have used propellers) to drive the object in a certain direction,” Ramakrishna said.
It may, however, not be possible to sustain that control over a long time, he noted. “So, if you can use the propeller to steer it into winds that are going in a favourable direction, the direction in which you want it to go, then you send it there.” After that, the balloon would still have to depend on favourable winds.
Napoleon’s spy balloon
In May 1794, the French engineer and scientist Jean-Marie-Joseph Coutelle, serving as a captain in Napoleon’s army, went up in a balloon to spy (in full view) on Austrian and Dutch troops during battle. An article from 1946 in The Atlantic archives describes how Coutelle stayed out of the range of Austrian gunners while relaying their positions to the French army.
Coutelle’s career as a balloonist ended when Admiral Nelson’s English fleet intercepted French ships in Egypt and burnt the balloon. While Coutelle escaped, Napoleon discontinued the balloon project after returning to France.
In subsequent centuries, ballooning would graduate to unmanned operations. By 1953, the US Air Force was testing balloons directed at the Soviet bloc, according to the Office of the Historian under the country’s State Department. By the middle of 1954, the Air Force had test-launched over 500 reconnaissance balloons in Project Moby Dick. The US later moved on to Project Genetrix, “the first US Air Force large-scale, unmanned, high altitude balloon intelligence operation”.
It was during the Cold War itself that the US moved on to U-2 reconnaissance aircraft.
Beyond espionage
Weather agencies across the world use balloons to gather information. In July last year, the Union earth sciences ministry told the Lok Sabha that the government was exploring the possibility of deploying drones in their place.
The US space agency, NASA, has been running a balloon programme to collect scientific information for several decades. And since 2017, NATO has been working on the “BALSAR project”, which aims to use a high-altitude balloon-borne radar to facilitate emergency responses and disaster relief.
In India, Dr Homi Bhabha pioneered scientific ballooning in 1950 under the aegis of the Tata Institute of Fundamental Research (TIFR), according to the earth sciences ministry. A TIFR facility in Hyderabad provides balloons to the Indian Space Research Organisation to measure wind profiles at its Sriharikota launch site.
