Space capabilities remained vital to the Soviet Union throughout the Cold War for maintaining its prestige as a peer superpower to the United States, and Moscow had ambitious plans to deploy the Buran space shuttle and Energia rocket in the 1980s.
But the factories responsible for producing the gigantic 7.75-meter diameter Energia rocket boosters necessary to sling spacecraft beyond the atmosphere were located Tushino and Kubyshev in Russia—while the Baikonur Cosmodrome launch facility was located hundreds of miles away in south-central Kazakhstan.
The boosters were too large for existing cargo aircraft, and yet too sensitive to be subject to the vibrations produced by a lengthy transit by truck or rail. And building the hundreds of miles of highway necessary for a few deliveries runs to Kazakhstan would have proven costly indeed.
So in 1976, the space flight program put out the requirement for an air transport solution for its giant rockets, even if it had to be specially built from scratch. A test attempting using two or three hulking Mi-26 heavy transport helicopters had to be ditched—literally—when the pilots were forced to drop the rocket booster as it began swinging in a pendulum-like fashion.
The Antonov design bureau, renowned for its transports, began work on the gigantic An-225 Mriya (“Dream”) to do the job. Today, the unique An-225 remains the heaviest aircraft ever built, and the one with the largest wingspan in service.