Yuri Gagarin got a good power-washing Monday atop his high pedestal overlooking Leninsky Prospekt. The city wants him looking his best on his big day, Tuesday, April 12, the 50th anniversary of the first human space flight.

Even as the crew of scrubbers went to work on a raw, damp day, red carnations were already strewn reverently around the life-size model of the Vostok spacecraft that sits below him at street level. There will be many more flowers by Tuesday. Gagarin is a hero beyond compare in Russia — a Soviet pioneer who transcends ideology, a national keepsake who stands for the sunniest moment of the 20th century.

“I was 7,” said Valery Morozov, who works for Moscow’s monument-maintenance squad. “I heard on the radio that man was in space. I remember I was so happy. People were so happy. They all went outside with flowers and slogans.”

The spray from the power washer drifted down from the region of Gagarin’s titanium shoes, about 120 feet above street level, crystallizing into snow before it hit the ground. It was warmer that day a half-century ago, Morozov recalled; this spring’s unendingly cold weather, he’s sure, has something to do with what happened at the Fukushima nuclear plant, in Japan.

The Yuri Gagarin of the monument looks like a rocket himself, gleaming and streamlined and seemingly hurtling upward toward the future. His powerful arms, in thick gauntlets that reach the elbows, stream slightly behind him, like fins. While he was alive, Soviet Premier Nikita Khrushchev had worried about a cult of personality developing around the daring young major, but by 1980 he had been dead for 12 years — killed in a plane crash — and he was safe for Soviet canonization.

The monument went up, facing west, by what was once the Kaluga Gate, guarding the approach to Moscow from both south and west. Gagarin came by this spot on his triumphant entry into Moscow on April 14, 1961, from Vnukovo Airport. People stood along his route all the way from the airport to the Kremlin, said Morozov, who was among the throng, and that evening everyone massed on Red Square for an unforgettable display of fireworks.

The busy intersection in front of him, now called Gagarin Square, looks like a bland spot, but as always in Russia there’s a history here. Napoleon stood at the Kaluga Gate on his disastrous retreat from Moscow in 1812 and, looking back, ordered the Kremlin destroyed. It wasn’t. When protest marchers were brutally dispersed in Boris Pasternak’s novel “Dr. Zhivago,” they were on their way to the Kaluga Gate. And, when, at the end of World War II, Soviet authorities decided to tear down the neighborhood’s old wooden single-family dwellings and replace them with big crescent-shaped apartment houses for officials of the interior ministry, among the prisoners who worked on their construction was Alexander Solzhenitsyn. He said those were the worst nine months of his life. The apartment houses are still there.

When Gagarin the cosmonaut passed this way in 1961, President John F. Kennedy had congratulated the Soviet Union on achieving a great step forward. (Alan Shepard made a sub-orbital flight for the United States in May 1961.) A Republican congressman from Pennsylvania said New York should hold a ticker-tape parade for Gagarin. That same day, Moscow Radio reported that the United States. was about to sponsor an armed intervention in Cuba, which sounded like propaganda but turned out to be true when, on April 17, a CIA-trained group of Cuban rebels went ashore at the Bay of Pigs. They failed, and a few months later Gagarin was in Havana, being feted by Fidel Castro.

Just 51 years before Gagarin’s flight into space, the Russian air force — the czar’s air force — got its start with rickety biplanes boasting wooden propellers. From one to the other was a huge leap, and there hasn’t been so much progress in the five decades since. Gagarin talked about going to Mars one day, but neither the Russians nor the Americans, distracted by other concerns, have gotten close.

On Monday, Alexei Guretski and a few other members of the Young Guard, a Kremlin-backed youth group, showed up at the monument, all in matching scarves the colors of the Russian flag. “It’s our history, the pride of our Russian people,” he said. “We must educate the young generation — tell them what this day is about.”

The Young Guard is opposed to any Russian who appears to be a dissident or to be less than enthusiastic about Prime Minister Vladimir Putin. Guretski is 27, Gagarin’s age when he flew into space. Would he be willing to do as much? “If my motherland calls me,” he replied.

He persuaded the cleaning crew to hoist a Young Guard banner up to Gagarin’s level. It didn’t look like much from the street, though — a stray piece of cloth perhaps, beneath the notice of the hero in the sky.