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While fatalities in human space exploration have been rare, the loss of life in missions such as the Challenger and Columbia space shuttles remains unforgettable. However, the number of missions that were on the brink of disaster is far higher. The following 10 manned spaceflights were perilously close to ending in tragedy, yet each time, the astronauts narrowly avoided death.
10. Soyuz 33
On April 10, 1979, the Soyuz 33 spacecraft launched, carrying two astronauts to the Soviet Salyut 6 space station. The crew included Bulgaria's first astronaut, Georgiy Ivanov, and Russian cosmonaut Nikolay Rukavishnikov. However, as they approached the space station, the Soyuz's main engine malfunctioned, causing the spacecraft to shake as it fired erratically. A second attempt to ignite the engine also failed, and the crew was instructed to sleep while the issue was assessed.
Rukavishnikov, unable to rest, feared that the malfunctioning main engine might have damaged the backup engine. If that were the case, the spacecraft would be stranded in orbit, unable to return to Earth, leaving the cosmonauts trapped in space. Although the Soyuz capsule was designed to naturally deorbit in 10 days, only enough oxygen for five days was available, meaning the crew would suffocate long before then.
Ultimately, the backup engine did ignite, but it fired for 25 seconds longer than intended, resulting in a steep angle of descent and ballistic reentry, subjecting the cosmonauts to 10 g forces. Fortunately, both astronauts were safely retrieved, bringing an end to the perilous mission.
9. Soyuz T-10-1
On September 26, 1983, commander Vladimir Titov and flight engineer Gennady Strekalov were set to be launched into orbit aboard Soyuz T-10-1, aiming to dock with the Soviet Salyut 7 space station. But ninety seconds before liftoff, a malfunction in a rocket engine's valve caused fuel to leak onto the launchpad. The fumes ignited, engulfing the rocket in flames. Despite this, the cosmonauts were not immediately in danger—their capsule was equipped with an escape tower designed to carry them away from the fiery rocket.
The only issue: The escape tower failed to activate. The fire had damaged the wiring responsible for triggering the system, leaving Titov and Strekalov atop a burning rocket, vulnerable to an explosion. The only way to ignite the escape tower was for two technicians in separate rooms in mission control to press two buttons simultaneously. By the time they managed to do so, 10 precious seconds had passed.
The escape tower activated just in time. Seconds after the cosmonauts were safely launched away, the rocket crumpled and exploded on the launchpad. Titov and Strekalov were so shaken that they turned off the cockpit voice recorder as soon as they were clear. When the recovery team reached them 30 minutes later, they requested cigarettes and vodka to calm their nerves.
8. Apollo CSM-111
On July 17, 1975, an American Apollo spacecraft successfully docked with a Soviet Soyuz spacecraft in orbit, marking the historic first international manned spaceflight. After undocking on July 19, the Soyuz spacecraft made a safe landing in Russia. However, the Apollo spacecraft faced a different fate. Just moments before splashdown in the Pacific Ocean, the three Apollo crew members noticed a yellow gas in the capsule, which irritated their eyes and triggered coughing fits. This was highly toxic nitrogen tetroxide, a propellant that is deadly if inhaled in high concentrations. To make matters worse, the capsule flipped over upon landing, trapping the astronauts inside. The crew rushed to grab the oxygen masks, and one astronaut had already lost consciousness by the time Thomas Stafford was able to reach them.
Stafford managed to activate the systems to upright the capsule and vent the toxic gas from the cabin. The crew was hospitalized for two weeks, but despite the close call, all the astronauts fully recovered. An investigation later revealed that a failure to flip a switch during pre-entry checks had left a valve open, allowing the lethal gas to leak into the capsule.
7. Liberty Bell 7
On July 21, 1961, the second manned U.S. spaceflight, Mercury-Redstone 4, known as Liberty Bell 7, was launched. Gus Grissom, set to be the second American in space, had a smooth flight with no issues. However, the splashdown proved far more dramatic. The capsule's exit hatch blew off prematurely, flooding the spacecraft. Grissom nearly drowned but managed to escape from the capsule.
The recovery helicopter struggled for several minutes to lift the spacecraft but eventually abandoned the attempt, allowing the capsule to sink. Grissom fought to stay afloat but had accidentally left a valve open in his suit, causing it to fill with water and become heavier. By the time the helicopter reached him, Grissom was so fatigued that he couldn’t even recall being lifted out of the water.
Grissom faced even more trouble afterward. At the first post-mission press conference, journalists questioned whether he had panicked and caused the hatch to blow, leading to the spacecraft's loss and his near-drowning. Grissom denied the allegations until his tragic death in the Apollo 1 fire in 1967.
6. Voskhod 2
On March 18, 1965, cosmonaut Alexei Leonov became the first human to leave his spacecraft, Voskhod 2, and perform an extra-vehicular activity, or spacewalk. Although this achievement was celebrated as yet another Soviet space first, the true story of this historic spacewalk is far from simple. In fact, it almost ended in tragedy multiple times.
While the exit and spacewalk went smoothly, when Leonov attempted to reenter his capsule, he discovered that his spacesuit had expanded in the vacuum of space, preventing him from entering feet-first. He had to enter head-first and, in a tense moment, release some air from his suit to fit back inside. This was a critical situation: If he failed to reenter within 40 minutes, he would suffocate. To make matters worse, his body temperature was rising dangerously due to the exertion. Leonov barely squeezed into the airlock just as he was running out of air. But his ordeal was far from over.
Upon reentry, a rocket malfunction left Leonov and his fellow cosmonaut stranded thousands of kilometers from help in Siberia. To make things even more perilous, they had landed in a forest swarming with aggressive wolves and bears, particularly hostile due to it being mating season. In freezing temperatures, the cosmonauts had to strip down and pour the sweat that had accumulated in their spacesuits to avoid frostbite. After enduring a harrowing night, they were finally rescued the next day when help arrived with tents and supplies.
5. Soyuz 5
Soyuz 5 was launched on January 15, 1969, with three cosmonauts aboard. Two days later, it docked with Soyuz 4, setting the stage for the first spacewalk involving two astronauts. After undocking, Soyuz 4 reentered and landed without incident. Soyuz 5, however, experienced a near-fatal mishap during its reentry.
After the deorbit burn, the Soyuz 5 reentry capsule, which had endured the intense heat of reentry, failed to separate from the orbital module. This malfunction resulted in the spacecraft reentering in the wrong direction, with the hatch facing forward instead of the heat shield. As the seals on the forward hatch began to burn, the cosmonauts feared they were facing certain death. However, fortune favored them. As g-forces and temperature increased, the oscillations caused by the reentry caused the orbital module to detach, and the reentry module quickly corrected itself, sparing the cosmonauts from disaster.
To make matters worse, the parachutes tangled during landing, creating a potentially fatal situation for the cosmonauts. Once again, luck intervened: The parachutes untangled at the last moment, though the landing was so rough that one of the cosmonauts ended up with broken teeth.
4. Apollo 13
The Apollo 13 incident is widely recognized as a remarkable disaster turned success through clever problem-solving and innovation. What is less commonly known, however, is that the Saturn V rocket, which propelled the mission, almost failed during launch. The culprit was a phenomenon called a pogo oscillation, a repetitive, self-perpetuating vibration caused by liquid-fueled rocket engines under certain conditions.
The oscillations occurred during the second stage firing. Although pogo oscillations had been seen in prior Apollo missions, the ones during Apollo 13 were far more intense than anticipated. The vibrations became so strong that they exceeded the measuring instruments' range, triggering an automated command to shut down the central engine, which halted the oscillations. A post-flight investigation revealed that the rocket was a mere one oscillation cycle away from catastrophic structural failure, which would have resulted in an immediate end to the mission before Apollo 13 even reached orbit. A pogo suppressor was added to all subsequent Apollo flights to dampen these oscillations.
3. STS-1
While the loss of the Challenger and Columbia shuttles is widely recognized, what is less commonly known is that the very first space shuttle mission, STS-1, was incredibly perilous. On April 12, 1981, precisely 20 years after Yuri Gagarin's launch, the Columbia blasted off. However, upon reaching orbit and opening the payload bay, the astronauts were shocked to discover missing heat-resistant tiles at the shuttle's rear. This raised alarms about the potential loss of tiles underneath the shuttle, which could have led to Columbia breaking up during reentry, 22 years ahead of schedule. Fortunately, despite many tiles being missing, the shuttle managed a safe landing.
But that wasn’t the only issue that arose during the mission. An overpressure wave from the solid rocket boosters caused the orbiter’s control flap to extend beyond its design limits, an event that shuttle designers had predicted would render the spacecraft uncontrollable during reentry. Though the designers' prediction was incorrect, the crew remained unaware of this potential fatal flaw until after landing.
When NASA performed a safety study on the shuttle 25 years later, they found that the failure rate for each of the first nine shuttle flights was one in nine. A death rate greater than 10 percent is alarming, especially considering NASA had initially estimated the failure rate at just 1 in 100,000.
2. Vostok 1
The first-ever manned spaceflight, Vostok 1, launched on April 12, 1961. Carrying cosmonaut Yuri Gagarin, it completed one full orbit around Earth before the automated systems activated the retro-rockets to return to the surface. Although the orbit was uneventful, the reentry proved to be a different story. Gagarin’s reentry module failed to detach from the service module due to a single wire bundle that wouldn’t come loose. The entire spacecraft began gyrating as it descended, and Vostok’s delicate forward hatch endured the intense heat of reentry.
Luckily, the wires burned through after 10 minutes, allowing the two modules to separate. Despite enduring significant deceleration forces and continued gyrations, Gagarin remained conscious, eventually ejecting and landing safely. The mission was uncertain in more ways than one. Vostok had been placed in a higher orbit than initially planned, which posed a serious risk—if the retro-rockets had failed, Gagarin would have been stranded in space beyond the limits of his food and oxygen supplies, which were only enough for 10 days. Furthermore, since no one had ever been in space before, mission planners genuinely feared that a man could go crazy in space. As a result, they locked Gagarin out of the spacecraft’s controls but allowed him emergency access if needed.
1. Gemini 6A
On December 12, 1965, the Gemini 6A capsule was scheduled to launch and rendezvous with Gemini 7, making history by conducting the first docking in space. However, the launch was interrupted when their Titan II rocket shut down just 1.2 seconds after engine ignition. The astronauts had been instructed to eject from their spacecraft if the engines cut off, as even a slight rise from the launchpad could send the rocket crashing back down. But the ejection seats presented their own dangers. The high acceleration used to propel the astronauts away from the capsule could easily result in their deaths. In test simulations, dummies had been used in ejection seat tests, but in several of these trials, the hatches failed to release, and the dummies were slammed head-first into the closed hatch with 20 g of acceleration.
Under immense pressure, the astronauts had to maintain a steady hand to prevent firing the ejection capsule. Having felt no acceleration, they correctly deduced that the Titan had not lifted off the pad. The launch was called off, but Gemini 6A successfully launched three days later.
