Wavery and high-pitched, the beep-beep signal picked up on Earth signalled the dawn of a new era.
Thursday marks the 50th anniversary of the Soviet Union's launch, on October 4, 1957, of Sputnik 1, the starting signal for the Space Race and a propaganda coup that Russia's present leaders can only envy.
The launch of the world's first man-made satellite, a silvery orb with four frond-like antennae and two radio transmitters, was at first obscure.
The official announcement was buried in leaden prose in the corner of a Pravda newspaper front page, the identity of Sputnik's creator kept a state secret.
But soon awed headlines in Western newspapers alerted Moscow to the true propaganda potential of Sputnik and as more space launches took place, carrying dogs and then the first spaceman, Yury Gagarin, the world was captivated by the achievement.
"The sense of pride was huge," recalled Olga Zenkova, leader of a children's group touring Russia's current cosmonaut training centre near Moscow, Star City, ready with carnations to lay at a statue of Gagarin.
"We felt we had to be first in everything."
The United States was caught badly off balance, flailing in its response as the Soviets launched a second satellite less than a month later, carrying Laika the dog, who was to die within hours.
The United States' hurried launch of the Vanguard satellite on December 6 that year was a flop, or "flopnik," as the London Daily Herald observed in a headline, barely getting off the ground before it burst into flames.
Some in the West immediately detected a threat: Britain's Manchester Guardian warned that Sputnik necessitated "a psychological adjustment" not only towards the Soviet Union but towards its military capabilities.
But in the early years, the space race, at least from Moscow's point of view, was less of a hostile affair than it was to become.
Sputnik's launch gave a psychological lift to Soviet society, marking a break from life under wartime dictator Joseph Stalin, who had died in 1953, and a sense of optimism in the new, easier era of Nikita Khrushchev.
"Society itself was very upbeat in the 1950s.... Space was associated with going beyond limits. In this case it was physics but it could be associated with going beyond tradition," said Boris Kagarlitsky, a writer on the period and director of the Moscow-based Institute of Globalisation.
"Although there was a military element in space projects... they were presented with a humanitarian aspect. The aspect of rivalry with the United States was not much evident in the beginning especially because the Soviets were leading."
As for Sputnik's creator, Sergei Korolyov -- dubbed "the chief designer" as his identity was kept from the public throughout his life -- he seems to have put behind him a painful past and thought only of work.
Science had literally saved Korolyov, securing his return from the Siberian Gulag prison system where he had been forced to work as a miner on trumped up subversion charges and where he lost most of his teeth and nearly 50 kilogrammes (110 pounds) in weight.
He was brought to work alongside other scientists and in a letter to his wife in 1953 mourned the death of Stalin, the man behind the Gulag, writing: "How this pains the heart, brings a lump to the throat. This really is a nationwide immense sorrow."
It was with iron determination that Korolyov went on to build Sputnik, jettisoning a more ambitious design when he heard of rival US plans and taking obsessive care to ensure its aluminium surface was spotlessly polished.
Contemporary accounts report that the day the carrier rocket was rolled from its hangar in Kazakhstan, Korolyov led the other designers in absolute silence for the whole 1.5 kilometre (one mile) walk to the launch pad.
Today Moscow appears to have lost the initiative, as the West ploughs unprecedented sums into space exploration and Washington deliberates on how long to maintain the International Space Station (ISS), a joint project with Russia.
At the Moscow house where Korolyov lived until his death aged 59, a tour guide, Valentina Golovkina, suggests he would have been "a bit sad" to see how Russia fell behind and failed to put a man on the Moon.
President Vladimir Putin has pressed into service the image of Korolyov as he exhorts Russia's scientists to up their game. There are plans afoot to send a probe to Mars and for a manned Moon mission by 2025.
In March he voiced pride that Russia had "paved the way for space exploration" but added: "We must... acknowledge that a whole decade, perhaps even more, of economic difficulties has had a negative impact on the development of our space sector."
In the last months of his life, as Korolyov laboured in the face of numerous health problems, he might have been surprised to learn that Russia would one day transport paying "tourists" to the ISS.
The next short-term visitor, Malaysian Sheikh Muszaphar Shukor, who is to blast off in October under an intergovernmental agreement, recently paid his respects to Russia's space achievements.
And Peggy Whitson, a US astronaut scheduled to blast off to the ISS next month, also paid tribute to "chief designer" and his Sputnik programme.
"It's why were going to space. I really recognize that the 50 year Sputnik anniversary is important to the whole world, not just to Russia."
That perhaps would have been enough for Korolyov as he pondered the future from the comfortable Moscow town house with which he was rewarded and where he tried to keep fit with morning gymnastics in his study.
"He did say people would one day go to space on trade union holidays," recalled the museum guide Golovkina.