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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
Crew Injury/Illness and/or Loss of Vehicle or Mission
Related or Recurring event
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.
LANDING & POSTLANDING