The Russian Soyuz spacecraft is the longest-flying spacecraft in history. Developed in the early 1960s, it was designed to give cosmonauts more control in space leading up to possible missions to the Moon. The three man spacecraft was the Soviet equivalent to NASA's Gemini; it could do everything a spacecraft going to the Moon needed to do. What it couldn't do, at least in its first iteration, was land back on Earth.
The Soyuz descent module was designed to separate from the instrument module and fire small retrofire rockets to reenter the atmosphere. A large parachute would slow its descent then, just before touchdown, rockets would fire to cushion the landing for the cosmonauts inside. Contrary to the Soviet Union's presentation of early Vostok and Voshod flights like Yuri Gagarin's, this was the first spacecraft that would land with cosmonauts still inside.
On April 20, 1967, that the prime and backup pilots for Soyuz 1 were confirmed – Vladimir Komarov and Yuri Gagarin respectively. The mission was complicated and risky. Komarov would launch on April 23. The following morning, Valery Bykovsky, Aleksei Yeliseev, and Yevgeny Khrunov would launch in Soyuz 2. Komarov in the more sophisticated spacecraft would rendezvous and dockwith Soyuz 2. Two cosmonauts would don spacesuits and transfer from Soyuz 2 to Soyuz 1 by spacewalk and the restructured crews would return from orbit.
The only problem with this flight plan was that it was beyond the capability of Soyuz at the time. Many engineers and cosmonauts doubted its safety and weren't convinced it would be ready in time. Unmanned test flights revealed serious problems and experienced failures that would have killed a human pilot, and while many called for more unmanned tests to work out the kinks, no one wanted to delay the launch. Communist Party bigwig Leonid Brezhnev wanted a launch on May 1, 1967, the National Day of Worker Solidarity. Because of who he was, if that was the day he wanted, that was the day he'd get.
Prime pilot Komarov had reason to be wary of the flight. There were known flaws in the spacecraft (203 to be exact) and engineers on the spacecraft's development team knew it wasn't ready for a manned flight. As the launch date approached, conscientious cosmonauts and engineers filed a ten page report outlining each of the flaws and arguing for the mission's cancellation.
It's not entirely clear what happened to that report, but it is clear that its message wasn't heeded. The Soviet system had a tendency to blame and punish the messenger, so getting the report into the right hands was only part of the problem. Venyamin Russayev, Yuri Gagarin's KGB escort and close friend, passed the report to a superior. The only result was his ban from ever engaging a cosmonaut or anyone affiliated with the space program in conversation again.
Days before launch, Russayev had dinner with Komarov and his wife. As the cosmonaut walked the KGB officer to the door, he turned to his guest and said plainly "I'm not going to make it back from this flight." Komarov went on to explain that his hands were tied. If he refused the flight, the politburo would strip him of his military honors and send Gagarin in his place. He couldn't send a close friend and national hero to his death.
The inevitable feeling that there would be a fatal end of the mission loomed in the air on launch day. Gagarin was particularly agitated, acting out and making strange demands. He wasn't supposed to go to the launch pad with Komarov, but he did and demanded a pressure suit as well. Some see Gagarin's actions as his attempt to elbow his way in to the cockpit to save his friend's life while others suggest this was his way of getting a pressure suit for Komarov. It wasn't much, but it would give the cosmonaut an added defense against a defective spacecraft. Another reading of Gagarin's actions is that he was trying to disrupt launch procedures enough to cancel the mission.

Once in orbit, only one of the two solar panels deployed, leaving the lopsided spacecraft limping along at half power. Soyuz 2 was then cancelled when it became clear the best course of action was to get Komarov home as quickly as possible. But as soon as the cosmonaut reentered the atmosphere, things went from bad to worse. The lopsided spacecraft was unbalanced and started spinning. Komarov couldn't control his attitude, and thus couldn't get his spacecraft's rounded bottom to face the ground, which meant this landing rockets wouldn't be able to cushion his landing. He tumbled as he fell straight down completely out of control.
During Soyuz 1's descent, Chairman of the Council of Ministers Alexei Kosygin cried as he told the cosmonaut he was a hero. Komarov's wife came on the line and the couple spoke about his affairs and said goodbye. Finally, the cosmonaut's yells of frustration and rage were the last sounds recorded from the spacecraft.
Soyuz 1 hit the ground with the force of a 2.8 ton meteorite. The capsule was instantly flattened under the force. Triggered the landing rockets that lit the wreckage on fire. Komarov's charred remains were uncovered and displayed during his funeral. The largest recognizable part of his body was his heel bone.
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