In the 1950s, early in the Cold War, the US enlisted balloons — because they had attributes that airplanes couldn’t match:
They could stay aloft for a long time (days or even weeks), they could reach altitudes where airplanes couldn’t fly (100,000 feet), and they could go places that were too dangerous for manned aircraft (flying over the Soviet Union).
America used to think big:
Project MOGUL was an Air Force balloon program to detect Soviet nuclear tests by listening to sound waves traveling through the upper atmosphere. During World War II, scientists had discovered the existence of an ocean layer that conducted underwater sound for thousands of miles. They thought that a similar sound channel might exist in the upper atmosphere. If they could put microphones in the upper atmosphere, the U.S. thought they might be able to hear Soviet nuclear tests and even detect ballistic missiles launches heading toward their targets. Designed to test this theory, Project Mogul balloons carried microphones up to the sound channel to “listen” and radio transmitters to send the sound to the ground. At first, project MOGUL flights involved trains of small weather balloons up to 600 feet in length. Later MOGUL flights used the large polyethylene balloons developed for the Navy’s SKYHOOK.SKYHOOK balloons, funded by the Office of Naval Research, were designed to stay at a fixed altitude (~100,000 feet) and carry a payload of thousands of pounds. They were huge, 400 feet high, made possible because the then new material called polyethylene. These “flying sandwich bags” were built by a company that had experience using this material in packaging – General Mills (the same company that makes Cheerios.)
In 1957 the Air Force started Project ASHCAN (using SKYHOOK class balloons at 100,0000 feet) to take high altitude air samples and search for nuclear particles and trace gases in fallout from tests in the Soviet Union. For the first time, U.S. intelligence could estimate the amount of plutonium being produced by Soviet weapons production reactors. These balloons were secretly launched from Brazil and the Panama Canal Zone, and from air force bases in the U.S. Over time, U.S. intelligence also used reconnaissance planes like the U-2, RB-57’s, and C-130 aircraft to collect air samples.
In 1950 the Air Force thought that high-altitude balloons might be used to perform photo and ELINT spyflights over the Soviet Union. They placed aerial reconnaissance cameras on the balloons and ran a series of test programs (code names of GOPHER, MOBY DICK, GRANDSON and GRAYBACK) launching 640 balloons from New Mexico, Montana, the West Coast, Missouri and Georgia. With the tests completed, the program name changed to GENETRIX and was given the designation of Weapons System 119L.In late 1955 President Eisenhower gave the ok to launch the GENETRIX balloons over the Soviet Union. Hundreds of these balloons took off from secret sites in Norway, Scotland, West Germany, and Turkey carrying a gondola with two reconnaissance cameras.
The United States launched 516 of the GENETRIX balloons but only 44 or so made it out of the Soviet Union. The rest landed on Soviet farms dumping 600-pound cameras in hayfields. We did get coverage of about 8 percent of the Soviet Union, but politically it created a lot of tension as cameras were popping up on Khrushchev’s desk. “Oh, another balloon Mr. Premier.” The Soviets put on a public exhibition of the equipment.
These high-tech balloons didn’t just spook the Soviets:
Before sunrise and after sunset, while the Earth below was dark, high altitude balloons were still lit by sunlight, and their plastic skin glowed and appeared to change color with the change in sun angle. Some of the Project Mogul balloon flights were launched from Alamogordo Air Base in New Mexico in 1947, and a few crashed nearby – one near a town called Roswell. The start of the Mogul balloon flights coincided with the first reports of UFO’s. To someone on the ground, these balloons may have looked like UFOs.