| Incident | Date | Mission | Description |
| Separation failure | 12 April 1961 | Vostok 1 | After retrofire, the Vostok service module unexpectedly remained attached to the reentry module by a bundle of wires. The two halves of the craft were supposed to separate ten seconds after retrofire. But they did not separate until 10 minutes after retrofire, when the wire bundle finally burned through. The spacecraft went into wild gyrations at the beginning of reentry, before the wires burned through and the reentry module settled into the proper reentry attitude. |
| Landing capsule sank in water | 21 July 1961 | Mercury-Redstone 4 | After splashdown in the Atlantic Ocean, the hatch malfunctioned and blew prematurely, filling the capsule with water and almost drowning Gus Grissom, who managed to escape before it sank. Grissom then had to deal with a spacesuit that was rapidly filling with water, but managed to get into the helicopter's retrieval collar and was lifted to safety. The spacecraft was recovered in 1999, having settled at the bottom of the Atlantic Ocean about 300 nmi (560 km; 350 mi) southeast of Cape Canaveral at a depth of about 15,000 ft (4,600 m). An unexploded SOFAR bomb, designed for sound fixing and ranging in case the craft sank, had failed and had to be dealt with when it was recovered from the ocean floor in 1999. |
| Space suit or airlock design fault | 18 March 1965 | Voskhod 2 | The mission featured the world's first spacewalk, by Alexei Leonov. After his twelve minutes outside, Leonov's space suit inflated in the vacuum to the point where he could not reenter the airlock. He opened a valve to allow some of the suit's pressure to bleed off, and was barely able to get back inside the capsule after suffering side effects of the bends. Because the spacecraft was so cramped, the crew could not keep to their reentry schedule and landed 386 km (240 mi) off course in deep forest. They spent a night sheltering in the capsule from the cold, and a second night in a temporary hut built by rescuers before skiing with them to a clearing where a helicopter flew them to Perm. |
| Engine shutdown at launch | 12 December 1965 | Gemini 6A | The first on-pad shutdown in the U.S. human spaceflight program. Gemini 7 orbiting 185 miles (298 km) directly over Missile Row witnessed the event and reported they could clearly see the momentary exhaust plume before shutdown. |
| Equipment failure | 17 March 1966 | Gemini 8 | A maneuvering thruster refused to shut down and put their capsule into an uncontrolled spin. After the Gemini spun up to one revolution per second, Neil Armstrong regained control by switching from the main attitude control system to the reentry system. Mission rules required a landing as soon as possible once the reentry thrusters were used, causing an early end to the flight. |
| Separation failure | 18 January 1969 | Soyuz 5 | Harrowing reentry and landing when the capsule's service module initially refused to separate, causing the spacecraft to begin reentry faced the wrong way. The service module broke away before the capsule would have been destroyed, and so it made a rough but survivable landing far off course in the Ural Mountains. |
| Struck twice by lightning during launch | 14 November 1969 | Apollo 12 | Two lightning strikes during launch. The first strike, at 36 seconds after liftoff, knocked the three fuel cells offline and the craft switched to battery power automatically. The second strike, at 52 seconds after liftoff, knocked the onboard guidance platform offline. Four temperature sensors on the outside of the Lunar Module were burnt out and four measuring devices in the reaction control system failed temporarily. Fuel cell power was restored about four minutes later. The astronauts spent additional time in Earth orbit to make sure the spacecraft was functional before firing their S-IVB third stage engine and departing for the Moon. |
| Struck by camera during splashdown | 24 November 1969 | Apollo 12 | Astronaut Alan Bean was struck above the right eyebrow by a 16mm movie camera when the spacecraft splashed down in the ocean. The camera broke free from its storage place. Bean suffered a concussion, and a 1.25 cm cut above the eyebrow that required stitches. |
| Premature engine shutdown | 11 April 1970 | Apollo 13 | During launch, the Saturn V second stage experienced a potentially serious malfunction when the center of its five engines shut down two minutes early. The remaining engines on the second and third stages were burned a total of 34 seconds longer to compensate, and parking orbit and translunar injection were successfully achieved. It was later determined that the shutdown was caused by pogo oscillation of the engine. |
| Equipment failure | 13 April 1970 | Apollo 13 | The crew came home safely after a violent rupture of a liquid oxygen tank deprived the Service Module of its ability to produce electrical power, crippling their spacecraft en route to the Moon. They survived the loss of use of their command ship by relying on the Lunar Module as a "life boat" to provide life support and power for the trip home. |
| One of three main parachutes failed | 7 August 1971 | Apollo 15 | During descent, the three main parachutes opened successfully. However, when the remaining reaction control system fuel was jettisoned, one parachute was damaged by the discarded fuel causing it to collapse. Spacecraft and crew still splashed down safely, at a slightly higher than normal velocity, on the two remaining main parachutes. If a second parachute had failed, the spacecraft would probably have been crushed on impact with the ocean, according to a NASA official. |
| Separation failure | 5 April 1975 | Soyuz 18a | The mission nearly ended in disaster when the rocket suffered a second-stage separation failure during launch. This also interrupted the craft's attitude, causing the vehicle to accelerate towards the Earth and triggering an emergency reentry sequence. Due to the downward acceleration, the crew experienced an acceleration of 21.3 g rather than the nominal 15 g for an abort. Upon landing, the vehicle rolled down a hill and stopped just short of a high cliff. The crew survived, but Lazarev, the mission commander, suffered internal injuries due to the severe G-forces and was never able to fly again. |
| Chemical poisoning | 24 July 1975 | Apollo–Soyuz | During final descent and parachute deployment, the U.S. crew were exposed to 300 μL/L of toxic nitrogen tetroxide (Reaction Control System oxidizer) fumes venting from the spacecraft and reentering a cabin air intake, because a switch was left in the wrong position. 400 μL/L is fatal. Vance Brand lost consciousness for a short time. The crew members suffered from burning sensations of their eyes, faces, noses, throats and lungs. Thomas Stafford quickly broke out emergency oxygen masks and put one on Brand and gave one to Deke Slayton. The crew were exposed to the toxic fumes from 24,000 ft (7.3 km) down to landing. About an hour after landing the crew developed chemical-induced pneumonia and their lungs had edema. They experienced shortness of breath and were hospitalized in Hawaii. The crew spent five days in the hospital, followed by a week of observation in semi-isolation. By 30 July, their chest X-rays appeared to return to normal except for Slayton; he was diagnosed with a benign lesion, unrelated to the gas exposure, which was later removed. |
| Landing capsule sank in water | 16 October 1976 | Soyuz 23 | The capsule broke through the surface of a frozen lake and was dragged underwater by its parachute. The crew was saved after a very difficult rescue operation. |
| Engine malfunction | 12 April 1979 | Soyuz 33 | Engine failure forced the mission to be aborted. It was the first failure of a Soyuz engine during orbital operations. The crew, commander Nikolai Rukavishnikov and Bulgarian cosmonaut Georgi Ivanov, suffered a steep ballistic re-entry, but were safely recovered. |
| SRB ignition shock wave overpressure reached design limits of orbiter structure | 12 April 1981 | STS-1 | During launch, the Solid Rocket Booster ignition shock wave overpressure was four times greater than expected (2.0 psi or 14 kPa measured vs 0.5 psi or 3.4 kPa predicted). Some of the aft structures on Space Shuttle Columbia reached their design limits (2.0 psi) from the overpressure. The overpressure bent four struts that supported two RCS fuel tanks in the nose of Columbia and the orbiter's locked body flap was pushed up and down 6 in (15 cm) by the shock wave. John Young and Robert Crippen in the crew cabin received a 3-G jolt from the shock wave. An improved water spray shock wave damping system had to be installed on the launch pad prior to launch. |
| Fire in launch vehicle | 26 September 1983 | Soyuz T-10-1 | A fuel spillage before the planned liftoff caused the vehicle to be engulfed in flames. The crew was narrowly saved by the activation of their launch escape system, with the rocket exploding two seconds later. |
| Leaked hydrazine fuel fire and explosion | 8 December 1983 | STS-9 | In the last two minutes of the mission, during Space Shuttle Columbia's final approach to the Edwards AFB runway, hydrazine fuel leaked onto hot surfaces of two of the three onboard auxiliary power units (APU) in the aft compartment of the shuttle and caught fire. About 15 minutes after landing, hydrazine fuel trapped in the APU control valves exploded, destroying the valves in both APUs. The fire also damaged nearby wiring. The fire stopped when the supply of leaked fuel was exhausted. All of this was discovered the next day when technicians removed an access panel and discovered the area blackened and scorched. It is believed that hydrazine leaked in orbit and froze, stopping the leak. After returning, the leak restarted and ignited when combined with oxygen from the atmosphere. There were no injuries during the incident. |
| Space Shuttle in-flight engine failure | 29 July 1985 | STS-51-F | Five minutes and 45 seconds into ascent, one of three main engines aboard Challenger shut down prematurely due to a spurious high temperature reading. At about the same time, a second main engine almost shut down from a similar problem, but this was observed and inhibited by a fast acting flight controller. The failed SSME resulted in an Abort To Orbit (ATO) trajectory, whereby the shuttle achieves a lower than planned orbital altitude. Had the second engine failed within about 20 seconds of the first, a Transoceanic Abort Landing (TAL) abort might have been necessary. No bailout option existed until after mission STS-51-L, the Challenger disaster. But even with that option, a bailout (a "contingency abort") would never be considered when an "intact abort" option exists, and after five minutes of normal flight it would always exist unless a serious flight control failure or some other major problem beyond engine shutdown occurred. |
| Sensor failure | 6 September 1988 | Mir EP-3 | At the end of the mission, Soviet cosmonaut Vladimir Lyakhov and Afghan cosmonaut Abdul Ahad Mohmand undocked from Mir in the spacecraft Soyuz TM-5. During descent they suffered a computer software problem combined with a sensor problem. The deorbit engine on the TM-5 spacecraft that was to propel them into atmospheric reentry, did not behave as expected. During an attempted burn, the computer shut off the engines prematurely, believing the spacecraft was out of alignment. Lyakhov determined that they were not, in fact, out of alignment, and asserted that the problem was caused by conflicting signals picked up by the alignment sensors caused by solar glare. With the problem apparently solved, two orbits later he restarted to deorbit engines. But the engines shut off again. The flight director decided that they would have to remain in orbit an extra day (a full revolution of the Earth), so they could determine what the problem was. During this time it was realised that during the second attempted engine burn, the computer had tried to execute the program that was used to dock with Mir several months earlier during EP-2. After reprogramming the computer, the next attempt was successful, and the crew safely landed on 7 September. |
| Thermal tile damage | 6 December 1988 | STS-27 | Space Shuttle Atlantis' Thermal Protection System tiles sustained unusually severe damage during this flight. Ablative insulating material from the right-hand solid rocket booster nose cap had hit the orbiter about 85 seconds into the flight, as seen in footage of the ascent. The crew made an inspection of the Shuttle's impacted starboard side using the Shuttle's Canadarm robot arm, but the limited resolution and range of the cameras made it impossible to determine the full extent of the tile damage. Following reentry, more than 700 tiles were found to be damaged including one that was missing entirely. STS-27 was the most heavily damaged Shuttle to return to Earth safely. |
| Space suit puncture | 8 April 1991 | STS-37 | During an extravehicular activity, a small stainless steel bar (palm bar) in a glove of EV2 astronaut Jay Apt's extravehicular mobility unit punctured the suit. The suit's pressure bladder and thin comfort glove conformed to the puncture and sealed it, preventing any detectable depressurization. Apt was unaware of the failure during the EVA, learning of it only when the suit manager phoned him the evening after he returned to Houston. During post-flight debriefings, Apt said after the second EVA, when he removed the gloves, his right hand had an abrasion behind the knuckle of the index finger. A postflight inspection of the right hand glove found the palm bar of the glove penetrating a restraint and glove bladder into the index finger side of the glove. NASA found air leakage with the bar in place was 3.8 SCCM, well within the specification of 8.0 SCCM. They said if the bar had come out of the hole, the leak still would not have been great enough to activate the secondary oxygen pack. The suit would, however, have shown a high oxygen rate indication. |
| Explosive release device punctured cargo bay bulkhead | 12 September 1993 | STS-51 | While releasing the Advanced Communications Technology Satellite from the payload bay, both the primary and backup explosive release devices detonated. Only the primary device was supposed to have detonated. Large metal bands holding the satellite in place were ripped away, causing flying debris. The debris punctured the orbiter's payload bay bulkhead leading to the main engine compartment, damaging wiring trays and payload bay thermal insulation blankets. The puncture in the bulkhead was 3 mm by 13 mm in size. The crew was uninjured and the damage was not great enough to endanger the shuttle. The satellite was undamaged. |
| Collision in space | 27 August 1994 | Mir | At Mir, during the 2nd docking attempt the Progress M-24 cargo freighter, the Progress freighter collided with the space station causing minor damage to the space station that was crewed at that time. |
| Eye injury from Mir exercise equipment | 18 May 1995 | Mir | While exercising on the EO-18/NASA 1/Soyuz TM-21 mission, astronaut Norman E. Thagard suffered an eye injury. He was using an exercise device, doing deep knee bends, with elastic straps. One of the straps slipped off of his foot, flew up, and hit him in the eye. Later, even a small amount of light caused pain in his eye. He said using the eye was, "like looking at the world through gauze." An ophthalmologist at Mission Control-Moscow prescribed steroid drops and the eye healed. |
| Fire on board | 23 February 1997 | Mir | There was a fire on board the Mir space station when a lithium perchlorate canister used to generate oxygen leaked. The fire was extinguished after about 90 seconds, but smoke did not clear for several minutes. |
| Fuel cell failure | 8 April 1997 | STS-83 | Fuel cell aboard Space Shuttle Columbia unexpectedly failed on Day 4 in orbit, forcing an early end to the flight. The mission touched down safely, and the crew was reflown with the same mission plan on STS-94. |
| Collision in space | 25 June 1997 | Mir | At Mir, during a re-docking test with the Progress M-34 cargo freighter, the Progress freighter collided with the Spektr module and solar arrays of the Mir space station. This damaged the solar arrays and the collision punctured a hole in the Spektr module and the space station began depressurizing. The onboard crew of two Russians and one visiting NASA astronaut were able to close off the Spektr module from the rest of Mir after quickly cutting cables and hoses blocking the hatch closure. |
| Main engine electrical short and hydrogen leak | 23 July 1999 | STS-93 | Five seconds after liftoff, an electrical short knocked out controllers for two shuttle main engines. The engines automatically switched to their backup controllers. Had a further short shut down two engines, Columbia would have ditched in the ocean, although the crew could have possibly bailed out. Concurrently a pin came loose inside one engine and ruptured a cooling line, allowing a hydrogen fuel leak. This caused premature fuel exhaustion, but the vehicle safely achieved a slightly lower orbit. Had the failure propagated further, a risky transatlantic or RTLS abort would have been required. |
| Toxic ammonia leak during EVA | 10 February 2001 | ISS/STS-98 | During EVA 1 on the mission, NASA astronauts Robert L. Curbeam and Thomas D. Jones were connecting cooling lines on the International Space Station while working to install the Destiny laboratory module. A defective quick-disconnect valve allowed 5% of the ammonia cooling supply to escape into space. The escaping ammonia froze on the spacesuit of astronaut Curbeam as he struggled to close the valve. His helmet and suit were coated in ammonia crystals an inch thick. Mission Control instructed Curbeam to remain outside for an entire orbit to allow the Sun to evaporate the frozen ammonia from his spacesuit. When they returned to the airlock, the astronauts pressurized, vented and then repressurized the air lock to purge any remaining toxic ammonia. After they removed their spacesuits, the crew wore oxygen masks for another 20 minutes to allow life-support systems in the airlock to further filter the air. No injuries resulted from the incident. |
| Ballistic reentry, injured shoulder | 3 May 2003 | Soyuz TMA-1 | The capsule had a malfunction during its return to Earth from the ISS Expedition 6 mission and performed a ballistic reentry. The crew was subjected to about 8 to 9 Gs during reentry. The capsule landed 500 kilometres (310 mi; 270 nmi) from the intended landing target. In addition, after landing the capsule was dragged about 15 metres (49 ft) by its parachute and ended up on its side in a hard landing. Astronaut Don Pettit injured his shoulder and was placed on a stretcher in a rescue helicopter and did not take part in post-landing ceremonies. |
| Unplanned rolls during ascent | 29 September 2004 | SpaceShipOne-16P | On suborbital flight 16P, the first of two flights that won the X-Prize for exceeding 100 km (62 mi) in altitude, astronaut Mike Melvill experienced 29 unplanned rolls during and after powered ascent. The rolls began at 50 seconds into the engine burn. The burn was stopped 11 seconds early after burning a total of 76 seconds. After engine cutoff, the craft continued rolling while coasting to apogee. The roll was finally brought under control after apogee using the craft's reaction jets. SpaceShipOne landed safely and Mike Melvill was uninjured. |
| Separation failure | 19 April 2008 | Soyuz TMA-11 | Reentry mishap similar to that suffered by Soyuz 5 in 1969. The service module failed to completely separate from the reentry vehicle and caused it to face the wrong way during the early portion of aerobraking. As with Soyuz 5, the service module eventually separated and the reentry vehicle completed a rough but survivable landing. Following the Russian news agency Interfax's report, this was widely reported as life-threatening while NASA urged caution pending an investigation of the vehicle. South Korean astronaut Yi So-yeon was hospitalized after her return to South Korea due to injuries caused by the rough return voyage in the Soyuz TMA-11 spacecraft. The South Korean Science Ministry said that the astronaut had a minor injury to her neck muscles and had bruised her spinal column. |
| Aborted spacewalk after water leak in suit | 16 July 2013 | ISS Expedition 36 | During EVA-23, European Space Agency astronaut Luca Parmitano reported that water was steadily leaking into his helmet. Flight controllers elected to abort the EVA immediately, and Parmitano made his way back to the Quest airlock, followed by fellow astronaut Chris Cassidy. The airlock began repressurizing after a 1-hour and 32 minute spacewalk, and by this time Parmitano was having difficulty seeing, hearing, and speaking due to the amount of water in his suit. After repressurization, Expedition 36 commander Pavel Vinogradov and crewmembers Fyodor Yurchikhin and Karen Nyberg quickly removed Parmitano's helmet and soaked up the water with towels. Despite the incident, Parmitano was reported to be in good spirits and suffered no injury. By December 2013, NASA had determined the leak to have been caused by a design flaw in the Portable Life Support System liquid coolant. The designers failed to take into account the physics of water in zero-g, which unintentionally allowed coolant water to mix with the air supply. |
| Hole detected in spacecraft | 30 August 2018 | Soyuz MS-09 | Ground controllers detected a dip in cabin pressure, which astronauts traced to a 2-millimeter hole in Soyuz MS-09, which was quickly patched up by Soyuz commander Sergey Prokopyev with epoxy. |
| Launch booster failure, ballistic re-entry | 11 October 2018 | Soyuz MS-10 | The crew reported feeling weightless; mission control declared a rocket had failed. An emergency was declared and the spacecraft carrying the crew was separated from the rocket. It returned to Earth in a ballistic descent (sharper than normal angle), and the crew experienced 6.7 G during the landing. The crew did not need immediate medical care when recovered. Investigation determined the ball joint supporting one of the side boosters had been deformed during assembly; the damaged joint prevented proper separation despite proper activation of the separation motors; the booster re-contacted the core stage, inflicting further damage. |
| Air leak in space station | August 2020 | Expedition 63 | NASA reported an air leak from the International Space Station during Expedition 63. The source of the leak was traced to the Zvezda module, but its exact location was unknown. |
| Uncontrolled spin of Space Station | 29 July 2021 | Expedition 65 | NASA reported an uncontrolled spin event after docking of the Russian Nauka module that replaced Pirs. It appears that the module's onboard computers incorrectly determined that it was still in open space rather than docked and fired its thrusters. Controllers had to fire the thrusters on Progress to counteract the (270 degree) spin and bring the station back into its correct orientation complicated by the module being out of range of Russian ground control stations, eventually however its propellant depleted and the situation was resolved. |
| Coolant Leak | December 2022 – January 2023 | Expedition 68 Soyuz MS-22 | On December 14, 2022, Cosmonauts Dmitry Petelin and Sergey Prokopyev were preparing for a spacewalk when a leak was detected on the Soyuz MS-22 spacecraft. After inspection by Canadarm2 and the European Robotic Arm, NASA announced on December 19, 2022, "A small hole was observed, and the surface of the radiator around the hole showed discoloration". Roscosmos said that there was a hole about 0.8 millimetres in diameter that caused the temperatures in MS-22 to go above 30 degrees Celsius. The cause of the hole and leak is under investigation however Roscosmos suspects micrometeoroids to be a potential cause. In January 2023 it was decided by NASA and Roscosmos to replace MS-22 with Soyuz MS-23. As an interim measure in case of an emergency evacuation is required, the seat of NASA Astronaut Frank Rubio will be moved to Crew Dragon Endurance with SpaceX Crew-5 while Prokopyev and Petelin would return to earth on MS-22. Once MS-23 arrives, the seats of Prokopyev, Petelin and Rubio would be moved to MS-23. As well, Sergei Krikalev of Roscosmos stated that the crew of MS-22 would have their mission extended by "at least, several more months" to allow the preparation of Soyuz MS-24. |
