On March 27, 1968, the MiG-15 UTI trainer flown by Gagarin and flight instructor Vladimir Seryogin crashed outside Moscow, killing both men. The official investigation provided all the details leading up to the crash, but could not definitively explain why the plane made the sharp maneuver which put it into a steep dive from which the cosmonaut proved unable to recover.
Investigators did not find any malfunctions in the MiG-15's equipment. Nor did toxicology reports find any evidence of foreign substances in the pilots' blood. Prior to the crash, Gagarin made no indication that anything had gone wrong and spoke in a calm, measured way.
In the fifty years since, the mystery behind the cosmonaut's last seconds has given rise to a variety of theories about what really happened that fateful morning in late March.
Another Plane: Cosmonaut Leonov's Theory
Alexei Leonov, the first human being to perform a spacewalk, believes that Gagarin's fateful dive maneuver was the result of the unauthorized flight of another plane in the area. "In the official investigation's conclusion, it was said that his plane made a sharp breakaway maneuver, entered a tailspin and collided with the ground…This is nonsense!" he said, speaking to RIA Novosti.
According to Leonov, "on March 27, 1968, during [Gagarin and Seryogin's flight], another, unauthorized aircraft ended up in the same area. This was a Su-15 flying out of Zhukovsky airfield. Its pilot violated regulations, descending to a height of 450 meters. I know after talking to witnesses that after turning on its afterburner, this plane passed 10-15 meters from Gagarin, flipping the latter's aircraft and sent it into a tailspin; or rather into a deep dive at a speed of 750 km per hour. The plane performed one and a half spins and, during its correction from the corkscrew, hit the ground," the cosmonaut said.
The documents confirm his version of events, Leonov said. "My reasoning has been confirmed by the opening of the declassified envelope containing the investigative commission's conclusions. There is no mystery here – only sloppiness and the violation of the flight regime. What disappoints me is that the people working in the commission, including [veteran cosmonaut trainer Nikolai] Kamanin knew the truth, but pretended not to. I would like for Gagarin's family to know the truth about his death."
Leonov says he knows the identity of the errant Su-15's pilot, who is now over 80 years old and in poor health, but has promised not to reveal it.
Poor Weather: Cosmonaut Vladimir Aksyonov's Theory
Veteran cosmonaut and two-time Hero of the Soviet Union Vladimir Aksyonov, who underwent a pre-flight medical inspection together with Gagarin on that fateful day in March 1968, says that a difficult meteorological situation and pilot error were to blame and not an unauthorized aircraft in the area.
According to the cosmonaut, the most likely outcome of the plane's entrance into the dense cloud cover at high speed without its special altitude systems (first and foremost its altitude reference indicator) is what pulled the plane into its steep downward spiral and resulted in the crash.
The official investigation concluded that Gagarin's plane exited the cloud cover in a nearly vertical position at a speed of almost 700 km per hour, flying a distance of 600 meters in just three seconds before hitting the ground.
"The lack of attempts to eject by either Gagarin or Seryogin, or attempts to communicate with base can be explained by the fact that entering the cloud cover was a surprise for them and after that they both tried to find a way out of the situation," Aksyonov noted. "If the emergency was associated with an external cause, the pilots would have immediately reported this by radio," he added.
Conspiracy Theories: From KGB Hit Job to Identity Change
About two decades later, at the height of perestroika, when many of the Soviet Union's heroes became the subject of critical reexamination, Gagarin's name was also subjected to conspiracies, each more absurd than the last. One version is that the cosmonaut got into a conflict with the USSR's leadership and that the KGB arranged for him to be murdered. Another variant of this version is the plane crash was faked and that Gagarin was actually arrested, he was forced to undergo plastic surgery and confined to a psychiatric hospital, where he died.
Other "investigators" have claimed that Gagarin faked his own death, after which he changed his name and moved to a village in Orenburg region, dying at a ripe old age as the result of a hunting accident. Another theory still is that Gagarin was killed during a test flight of a secret spacecraft for the Soviet moon mission and that the MiG-15 crash was faked afterwards.
"I could have gone on flying through space forever." – Yuri Gagarin
Ultimately, while the mystery of what exactly happened to Gagarin and Seryogin during their final moments of life will live on, so too will the space pioneer's legacy as the first human being to slip the surly bonds of Earth and dance the skies on laughter-silvered wings, paraphrasing John Gillespie Magee Jr.