Their statues lie scrapped or neglected. Their achievements rubbished. And their life stories are forgotten or mocked.
Only one poster boy of the USSR remains: Yuri Alekseyevich Gagarin. The mere mention of his name sees Russian chests swell with pride. His achievements are legendary and he is unique in transcending the country's harrowing transition from Communism to capitalism.
Any Russian school child can tell you that the Soviet cosmonaut was the first man in space. And his mission aboard the capsule Vostok 1 won the space race for the Soviets when it orbited the Earth on 12 April 1961.
Gagarin was just 27 years old when he grabbed the headlines around the world. The son of collective farm workers and a devoted family man with a wholesome sense of humour and movie star looks, he quickly captured the imagination of a generation.
His flight, which lasted just one hour and eight minutes, was a milestone in the space race that developed between the competing superpowers and one which demonstrated in no uncertain terms that the then USSR was a force to be reckoned with.
Gagarin epitomised "Homo Sovieticus", was the apogee of Soviet Socialism and the product of a system that Moscow then believed would establish global hegemony.
Who remembers Alan Shepard, the first American in space who reached orbit on 5 May of the same year?
A deeply sarcastic poster that festoons modern-day Moscow displays a famous Russian tourist knick-knack - a Matroshka doll - and warns passers-by that if they're not careful Russia will have nothing else to be proud of. That cynicism bounces off Gagarin. He lives on in the Russian imagination as a reminder of one of their greatest triumphs and someone about whom they can genuinely feel good.
Only one thing clouds the golden memory of Russia's feted cosmonaut and that is how he died. Mystery continues to shroud the fate of the first man in space: almost 40 years after his tragically premature death, nobody really knows how and why Gagarin died.
It is a riddle that continues to fascinate Russians in the same way that Americans still puzzle over who shot John F Kennedy and fans of Diana, Princess of Wales, continue to speculate about what caused the car crash that killed her.
Now a group of eminent military and space officials, test pilots, accident investigators and medical specialists have drawn up a petition asking for the Gagarin investigation to be reopened. The petition will soon be received by Russian President Vladimir Putin and the Russian parliament.
A new theory concerning Gagarin's demise has also been put forward by one of the surviving members of the government commission that originally investigated his death.
The bare facts of the tragedy, which occurred on 27 March 1968 just outside Moscow, have long been in the public domain.
Gagarin and his flight instructor, Vladimir Serugin, were flying a routine test mission in a MiG-15 in what were admittedly poor weather conditions.
The duo had successfully completed the day's manoeuvres and were heading for the airstrip when radio contact with the plane was lost.
Rescuers would later find what was left of the MiG-15 at the bottom of a deep crater in a forest. Both men were dead and their bodies badly mangled.
Gagarin was just 34 and, at the time of his untimely death, had been the favourite to lead the Soviet Moon-landing mission (the Americans beat the Soviets to it in 1969).
His plane appeared to have gone into a "black nosedive" from which it could not recover and the pilots seem to have lost all control. A government commission was formed to find out what had happened to a man who was a holder of the Order of Lenin and a hero of the Soviet Union.
People cried on the Moscow metro when they heard the news and thousands of Russians queued for days to catch a glimpse of the urn containing his ashes. About 200 experts took part in the investigation that followed but the then Soviet leader Leonid Brezhnev suppressed its findings and consigned the 30-volume report to the archives. Investigators were forbidden from publishing a summary of their conclusions on the grounds that it would "unsettle" the nation and the matter was quietly forgotten as Soviet tanks rolled into Czechoslovakia to crush the Prague Spring.
Even his immediate family was not told what had really happened, prompting his mother, Anna, to ask years later whether her famous son had been murdered by the Brezhnev regime, a theory which refuses to die. Gagarin, briefly the world's most famous person, was buried at the foot of the Kremlin Wall alongside Soviet luminaries such as Joseph Stalin.
Over the years conspiracy theories flourished like mushrooms in the rain and various official theories began to leak out too.
The unkindest theory was that the two men were drunk on vodka and had lost control. Gagarin had found fame hard to deal with in the years following his triumphant return to Earth, it was argued, and had become a heavy drinker.
However, official accident reports would show that no traces of alcohol had been found in either man's blood.
Other theories bordered on the lunatic: that he had been abducted by aliens, that he had survived the crash and died in a Soviet psychiatric ward in 1990, that Serugin had killed both of them because he was jealous of Gagarin, that Gagarin had staged his own death and had plastic surgery or that he had been shot down by the CIA.
Investigators also speculated that the plane had collided with a foreign object, a weather balloon or a flock of birds, but found no signs on the fuselage to back up such a theory. Nor could they find anything wrong with the plane's controls or engines. In short the accident remained shrouded in mystery.
No one could understand, for example, why the two skilled and experienced pilots had not ejected from the plane.
Russian media reports at the time had Gagarin heroically staying at the controls to ensure that the plane did not smash into a nearby school, but no real evidence was ever produced to support this. A 1986 inquest suggested that the MiG-15 had been knocked off course by turbulence from a supersonic aircraft in the area.
That and the theory that the plane had swerved violently to avoid hitting a weather balloon have become the received versions of events. Most surviving officials say that air traffic control at the local airfield was in a pitiful state on the day Gagarin died. However, Igor Kuznetsov, a member of the original government commission and a retired Soviet aircraft engineer, has put forward a new theory.
"I've finally managed to get to the bottom of this," he told the Russian media. "With the help of the latest computer programmes, I have managed to work out the trajectory and precise movements of the plane in its last moments.
"I have completely recreated the events of 37 years ago and believe that I have found the real cause of the catastrophe."
Mr Kuznetsov says someone had forgotten to close a ventilation panel in the cockpit, that the cabin lost pressure as a result and that the two men then passed out. He said: "So judging by everything, the reason for the tragedy was the human factor, the incompetence of one of the mechanics preparing the plane for flight."
Crucially Mr Kuznetsov did not rule out the possibility of foul play, a suggestion that is likely to spark fresh speculation about whether Gagarin was actually murdered by the Brezhnev regime. Although the cosmonaut enjoyed excellent relations with Nikita Khrushchev, the Soviet leader at the time of his historic flight, he was on much cooler terms with Brezhnev. The former Soviet leader was said to be irked by Gagarin's continued fame, and felt overshadowed by him at public events. Brezhnev saw him as a creature of the man he had deposed.
There are also suggestions that Communist officials were deeply embarrassed by Gagarin's purportedly increasingly alcohol-fuelled behaviour and alleged philandering. On one occasion, for example, when he was apparently in flagrante delicto with a nurse in the Crimea, he is said to have leapt off a balcony and badly smashed up his face when his wife knocked at the door.
His faithful legion of fans say such tales have been invented by domestic ill-wishers and foreign historians eager to discredit one of Russia's greatest historical figures. That may be true, but conspiracy theorists and the curious have other grounds to believe that he incurred Brezhnev's wrath.
It is believed that Gagarin tried in vain to prevent the launch of the faulty Soyuz spacecraft in which cosmonaut Vladimir Komarov died in 1967, an event that was a severe embarrassment to the USSR at the time.
Almost 40 years after his tragic death Russia is eager to know the truth. "The plane crash which killed our national hero, the planet's first cosmonaut Yuri Gagarin, and his instructor still remains unsolved and the reasons for their death unknown," reads the petition demanding a fresh investigation.
"The official conclusions have still not been published and as a result the investigation has legally not been completed."
Whether the truth about Gagarin, a man who was received by the Queen of England, toured the world and ventured quite literally where no man had ever been before, will ever be known remains uncertain.
With Russia looking harder than ever for heroes capable of carrying the weight of hope and expectation, the ghost of the man whose hour-long stellar voyage propelled him from farmer's son to Soviet icon will not be allowed to rest quietly.
The space race
* 31 JULY
Soviet Union announces intention to launch a satellite into space two days after the United States declared it would.
* 4 OCTOBER
Soviet Union launches the world's first satellite, Sputnik 1. The satellite, weighing 90kg, orbited the earth for three months. Industrial output in the Soviet Union rocketed during the decade, and the launch was a demonstration of the might of the Soviet system.
* 3 NOVEMBER
Sputnik 2 is launched. Its passenger, a dog called Laika, is the first living being in orbit.
The US government creates the National Aeronautics and Space Administration, Nasa.
* 12 APRIL
Soviet cosmonaut Yuri Alekseyevich Gagarin is the first man in space on Vostok 1.
* 5 MAY
Alan Shepard is the first American in space on a 15-minute sub-orbital flight. Nine months later, John Glenn is the first American to orbit the Earth.
* 16-19 JUNE
Soviet cosmonaut Valentina Tereshkova becomes the first woman in space, on Vostok 6.
* 18 MARCH
Aleksei Leonov, cosmonaut on Voskhod 2, makes first space walk. The mission nearly ends in disaster: Leonov has trouble returning to capsule, and ship lands 1,000 miles off target.
* 27 MARCH
Yuri Gagarin is killed with flying instructor during MiG-15 training flight near Moscow. Cause of the crash is uncertain.
* 20 JUNE
US wins round two of the space race when Apollo 11 lands on the moon and Neil Armstrong walks on the surface.
* 26 DECEMBER
Soviet Union launches Salyut 4, the first orbital space station.
* 15 JULY
The Soviet craft Soyuz 19 docks in space with America's Apollo 18. For the first time, astronauts from the rival nations pass into each other's ships and conduct experiments together.