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Abort Guidance System
Auxiliary Power Unit
Abort to Orbit
Russian Micropurification Unit (Russian)
Carbon Dioxide Removal System
Colony Forming Unit
Control Moment Gyroscope
Cell Performance Monitor
Compound Specific Analyzer-Combustible Products
Extravehicular Mobility Unit
Electrical Power System
Fuel Cell Monitoring System
Functional Cargo Block (Russian)
Flight Safety Office
Galley Iodine Removal Assembly
Guidance, Navigation, and Control
General Purpose Computer
Global Positioning System
Inertial Measurement Unit
International Space Station
Internal Thermal Control System
Launch Control Officer
Low Iodine Residual System
Loss of Crew
Loss of Vehicle
Minimum Duration Flight
Master Events Controller
Main Landing Gear
Micro-Meteoroid Orbital Debris
Marshall Space Flight Center
NASA Standard Initiator
Office of Safety & Mission Assurance (NASA HQ)
Protuberance Air Load
Precision Approach Path Indicator
Primary Avionics Software System
Pyrotechnic Initiator Controller
Partial Pressure of CO2
Reaction Control System/Subsystem
Remote Manipulator System
Russia or Russian
Return to Launch Site
Safety & Mission Assurance
Solid Fuel Oxygen Generator
Solid Rocket Booster
Condensate Water Processor Unit (Russian)
Space Shuttle Main Engine
Space Shuttle Program
Thermal Protection System
Loss of Crew
Apollo 12 11/24/1969
Apollo 15 8/7/1971
Apollo ASTP 7/24/1975
Skylab 2 5/26/1973
Apollo 11 7/21/1969
Apollo 10 5/22/1969
Apollo 1 (AS-204) 1/27/1967
Apollo 12 11/14/1969
Apollo 13 4/11/1970
Apollo 12 | 11/24/1969 | Crew: 3
Harder than normal splashdown knocked loose a camera. The camera knocked lunar module pilot unconscious.
Due to a harder than normal splashdown on November 24, 1969, a camera broke free from the window bracket and struck the lunar module pilot on the forehead. The crew member was unconscious for five seconds after the injury and required sutures following retrieval.
Apollo 15 | 8/7/1971 | Crew: 3
Landed with only 2 of 3 parachutes.
On August 7, 1971 the Apollo capsule, Endeavour, dropped into the Pacific Ocean about 320 miles (515 kilometers) north of Hawaii. During the Earth landing phase, after the main parachutes were deployed and shortly after Reaction Control System (RCS) propellant dumping, one of the main parachutes was observed to be deflated when exiting the clouds (3 of 6 fabric risers failed and two-thirds of the suspension lines were missing). One of the main parachutes was recovered after landing, but the failed parachute was not recovered.
The investigation was divided into three areas which were likely causes of the parachute failure.
The forward heat shield was suspected because of the close proximity to the spacecraft flight path during the period when the failure occurred.
A broken riser/suspension-line connector link was found on the recovered parachute, indicating the possibility of broken links in the failed chute.
The Command Module RCS propellant depletion firing had just been completed, and fuel (monomethyl hydrazine) expulsion was in progress at the time of the failure, indicating the possibility of damage from propellants.
Analysis and testing ruled out possible causes one and two, but a test of raw fuel expulsion after RCS firing produced burning outside of the engine. The flame front extended up to eight feet from the engine exit and unburned fuel was sprayed up to 10 feet from the engine and ignited by burning droplets. This was considered the most likely cause of the parachute failure.
Apollo ASTP | 7/24/1975 | Crew: 3 | Crew Injury
N2O4 in crew cabin. Crew hospitalized for 2 weeks.
On July 24, 1975 as the spacecraft descended, the commander, who was reading the checklist, failed to tell the command module pilot to move the Earth Landing System auto/manual switch to auto. The crew saw that the spacecraft was well below the deployment altitude and proceeded to manually deploy the chutes. Drogue chutes were deployed manually at 18,550 feet instead of 23,500 feet as the automatic system would have done. At 10,000 feet the commander realized that ELS was not in AUTO and quickly switched ELS Logic and AUTO, deploying the main parachutes at 7,150 feet and disabling the RCS instead of 10,500 feet.. The Reaction Control System (RCS) was not disabled manually (RCS command switch turned to “off”) at this time. It was disabled manually at 16,000 feet instead of when the checklist indicated at 24,000 feet. The cabin pressure relief valve opened automatically at 24,500 feet.
During a 30-second period of high thruster activity after drogue parachute deployment, a mixture of air and propellant combustion products followed by a mixture of air and nitrogen tetroxide oxidizer (N2O4) vapors were sucked into the cabin. One of the positive roll thrusters is located only two feet away from the steam vent that pulls in outside air when the cabin relief valve is open. This exposed the crew to a high level of N2O4 since emergency oxygen masks were not available until landing. The pilot passed out, but the commander quickly put the oxygen mask on him and he was revived. The exposure resulted in a two-week hospital stay for the crew after landing.
Skylab 2 | 5/26/1973 | Crew: 3 | Related or Recurring event
Multiple failed automatic docking attempts resulted in manual docking to Skylab.
On May 26, 1973 numerous failed docking attempts resulted in the use of contingency in-flight procedures to bypass the automated docking system. Successful docking to the Skylab station ultimately relied on manual control and crew piloting skills.
The contingency procedure required the Skylab 2 crew members to don pressure suits, depressurize the command module cabin, open the tunnel hatch, cut wires in the probe, and connect the emergency probe-retract cable using a utility power outlet. The crew members were able to fire the probe-retract pyrotechnic and complete docking manually.
The failure to dock would have resulted in the loss of Skylab due to the inability to perform critical repairs.
Apollo 11 | 7/21/1969 | Crew: 2
Engine arm circuit breaker knob broke off. Circuit breaker successfully reset allowing ascent.
On July 21, 1969 while preparing for extravehicular activities, the engine arm circuit breaker broke, probably due to an impact from the oxygen purge system. A felt tipped pen was used to successfully depress the circuit breaker when needed. Circuit breaker guards were installed on Apollo 12 and subsequent vehicles to prevent the oxygen purge system from impacting the circuit breakers.
Apollo 10 | 5/22/1969 | Crew: 2
Switch misconfiguration resulted in lunar module control problems.
In May 22, 1969 a switch misconfiguration resulted in lunar lander control problems.
During the Lunar Module (LM) last pass, within eight miles of the moon and prior to the jettison of the LM Descent Stage, the Commander (while wearing a space suit) started to troubleshoot an electrical anomaly.
The Abort Guidance System (AGS) was inadvertently switched from HOLD ATTITUDE to AUTO, which caused the LM to look for the Command/Service Module (CSM) and flip end over end.
The attitude indicator was going to the red zone and in danger of tumbling the inertial platform. The Commander was able to grab the hand controller, switch to manual control, jettison the Descent Stage, control the LM Ascent Stage, and finally dock with the CSM.
Apollo 13 | 4/13/1970 | Crew: 3 | Loss of Mission
Explosion due to electrical short. Loss of O2 and EPS.
Apollo 13 launched on April 11, 1970. On April 13, 1970 during trans-lunar flight at approximately 56 hours, one of the two Service Module oxygen tanks over-pressurized and exploded. This caused the loss of oxygen in that tank and a leak of oxygen out of the remaining tank. This resulted in the loss of all three fuel cells, loss of the primary oxygen source, and the loss of electrical power to the Command Module (except for the entry batteries). The mission was able to continue with the use of the Lunar Module, and the crew safely returned.
Prior to launch, the following conditions resulted in the oxygen tank failing during the mission: By design the cryogenic oxygen tank required both electrical heaters to maintain pressure, and fans to prevent stratification. The tank was a complex assembly with blind installation of the quantity probe, heater/fan assembly, and fill tube. This design leaves wiring insulation vulnerable to damage during assembly with no way to inspect after installation. The Teflon insulated wiring, which is a combustible material in the oxygen tank, was in close proximity to the heater elements and fan.
The Apollo 13 tanks were originally installed on Apollo 11, but a change required the tanks to be removed. During removal of the oxygen shelf, one bolt was left in place causing the fixture to break and resulting in a two-inch drop of the shelf and tanks. Although a loosely fitting (due to loose specification tolerances) fill tube could have been displaced by this, all testing was passed. No cryogenic tests were performed which would have revealed the problem. During the Count Down Demonstration Test the oxygen tank could not be emptied by the normal means of pressurized oxygen gas due to a leak at the fill tube. Instead, the tank heaters were turned on to boil off the oxygen in the tank. The thermostatic switches were rated for 30 volts direct current, but several years earlier the heater ground power supply voltage was raised to 65 volts to reduce the pressurization time. As the temperature increased the thermostatic switch opened and the higher voltage caused the contacts to weld closed. With the heaters continuously on, the temperature approached 1000 degrees and damaged the wire insulation, setting up the conditions for a short and ignition inside the tank. Ground personnel did not notice the continuous heater operation. During the prelaunch problem solving neither the Apollo Spacecraft Program Manager nor the Kennedy Director of Launch Operations knew the tank had previously been dropped or that the heaters had been on for eight hours.
Apollo 14 | 1/31/1971 | Crew: 3
Multiple failed docking attempts. Contingency procedures developed to mitigate risk of recurring docking anomaly. Docking successful.
On January 31, 1971 six docking attempts were unsuccessful following translunar injection. On the seventh try the command module pilot was told to fire thrusters to hold the command module to the lunar module while the docking probe was retracted. The docking capture latches were triggered to fire the probe-retract pyrotechnic, and docking was successful. After docking, the drogue and probe were examined by the crew and appeared normal. No other issues arose with the docking mechanisms.
The most likely cause of the docking issue was a piece of debris or ice on the docking probe from rain water entering the boost shroud the day before launch. The mission would have been No-Go for lunar module separation and landing if a backup procedure for docking and retracting the docking probe in an emergency had not been developed.
Apollo I (AS-204) | 1/27/1967 | Crew: 3 | Loss of Crew
Crew cabin fire (electrical short + high pressure O2 atmosphere).
On January 27, 1967 the crew cabin of Apollo 1 caught fire during a test with three crew members inside. The cabin was filled with a pure oxygen atmosphere and pressurized greater than ambient pressure (16.7 psi). Over the course of several hours, the oxygen permeated all materials in the cabin, which had been tested to the normal flight pressure of pure oxygen (5 psi). When the fire began it spread rapidly. Due to the pressure in the cabin, the crew members could not open the hatch to escape. Technicians in the room outside the capsule attempted to open the hatch but were driven back by the heat and smoke. Some technicians donned the available gas masks, but the masks were designed to protect against hypergolic propellant fumes, not smoke. Consequently, these technicians lost consciousness after a short time in the smoke-filled room.
All three crew members were lost.
The fire was caused by an electrical short from an unprotected wire. A subsequent review of all wiring dioded to both Main Bus A and B identified a problem with an environmental control system instrumentation wire powered from Main Bus A and B. The wire was routed over plumbing lines on the crew compartment floor, located below the left-hand crew seat, going into the left-hand equipment bay, between the environmental control unit and the oxygen panel. This Teflon-insulated wire should have had a protective Teflon overwrap, but closeout photos showed that the overwrap had slipped down, no longer providing protection. The commander likely contacted this wire with his foot when he turned to change his communications cable. The most probable initiator of the fire is an electrical arc from this wire, which was unprotected from external damage.
Factors contributing to this accident include:
Apollo 12 | 11/14/1969 | Crew: 3
Lightning strike on ascent.
During the Apollo 12 launch on November 14, 1969 lightning struck the spacecraft.
Light rain was falling, but weather conditions did not indicate any thunderstorm activity. There were seven miles of visibility with cloud break estimated at 800 feet and overcast conditions at 10,000 feet.
At 11:22am, T+36 seconds, the crew saw a bright light.
At T+36.5 seconds many errors occurred: Fuel Cells 1, 2, and 3 disconnected; Main Buses A and B were under-voltage; Alternating Current (AC) Buses 1 and 2 overloaded. The warning lights and alarm came on in the cabin, indicating failure of the Inertial Stabilization System.
At T+52 seconds (13,000 feet) lightning struck the vehicle and the Inertial Measurement Unit platform tumbled.
The potential effect on the vehicle was induction into wiring, depending on the location and rate of change of potential and direct current flow in grounding. The high negative voltage spike (delta voltage/delta time) caused the Silicon Controlled Rectifiers to trip on the Fuel Cell and AC Inverter overload sensors. Failures occurred in four Service Module Reaction Control System helium tank quantity measurements, five thermocouples, and four pressure/temperature transducers.
Using power from the Battery Relay Bus, the crew reconnected the Fuel Cells to Main Bus A and B, and reconnected the inverters to AC Bus 1 and 2. The mission continued.
Apollo 13 | 4/11/1970 | Crew: 3
2nd stage center engine shutdown due to pogo oscillations.
During the April 11, 1970 launch of Apollo 13 severe pogo oscillations were experienced. Acceleration at the engine attachment reached an estimated 34 g (the accelerometer went out of recordable range) before the engine's combustion chamber low-level pressure sensor commanded an engine shutdown.
Crew Injury/Illness and/or Loss of Vehicle or Mission
Related or Recurring event
LANDING & POSTLANDING