* The Apollo Service Module got power from reacting oxygen and hydrogen in a fuel cell, this is a separate supply from the fuel tanks and the life support oxygen.
* The liquid oxygen tank had a fan to stir the liquid and gas layers to get more accurate measurements.
* A melted/exposed wire for powering the fan caused a fire that exploded that LOX tank which also destroyed the pipework for the other LOX tanks.
* All three fuel cells in the Service Module were useless and the CSM had no electrical power.
* They were able to use the LEM as a lifeboat and the limited battery supply (intended for landing after jettisoning the Service Module) for the essential engine burns to get them home.
Now the chronological order:
* During construction of Apollo 10 they installed a module with the LOX tanks which then had a design change to add more shielding for EM interference.
* When removing the module someone overlooked a bolt and the panel wouldn’t slide out properly so someone used force and caused an impact of some of the components.
* Insufficient testing was done to confirm everything worked properly and the damaged module was eventually installed in Apollo 13.
* Pre-launch tests included filling all the cryogenic tanks, this worked fine. Next they had to empty all the tanks, this did not work fine. Evidently the drain line on this fuel cell LOX tank was damaged.
* Plan B to drain the tank was to turn on the electric heater and just boil off the excess LOX.
* The heater was specified to run on Apollo’s own low voltage power supply but a late change had it capable of running off the higher voltage power from the ground equipment.
* Technically the heater DID work on the higher voltage and it did heat the tank. But no one had tested if the thermostatic cutoff would work.
* The higher voltage welded the thermostats contacts together and meant the heater didn’t shut off from overheating and kept running on full power overnight
* The tank overheated massively, first boiling off the oxygen but then burning the insulation on the wires for the heater and for the fan
* No one knew the wires were damaged and launch went ahead as scheduled
* A few hours into flight, Kevin Bacon was told to “stir the tanks” i.e. activate the fans and mix the LOX and GOX.
* The damaged wires caused a fire which in the pure oxygen environment burned the insulation and blew up the tanks.
* Later changes to the Apollo Service Module design added redundancy in case of catastrophic electrical failure but the biggest change was not to bother with the fan to stir the tanks, turns out measuring unstirred tanks wasn’t as hard as they thought.
tl;dr It’s all Kevin Bacon’s fault.
Outrageous-Point-498 on
Amazing video. Very detailed and the 25char
wons-noj on
I loved this video. Def worth the background listen even if you know the story
5 Comments
Cool video. Put it in my watch later
Short version:
* The Apollo Service Module got power from reacting oxygen and hydrogen in a fuel cell, this is a separate supply from the fuel tanks and the life support oxygen.
* The liquid oxygen tank had a fan to stir the liquid and gas layers to get more accurate measurements.
* A melted/exposed wire for powering the fan caused a fire that exploded that LOX tank which also destroyed the pipework for the other LOX tanks.
* All three fuel cells in the Service Module were useless and the CSM had no electrical power.
* They were able to use the LEM as a lifeboat and the limited battery supply (intended for landing after jettisoning the Service Module) for the essential engine burns to get them home.
Now the chronological order:
* During construction of Apollo 10 they installed a module with the LOX tanks which then had a design change to add more shielding for EM interference.
* When removing the module someone overlooked a bolt and the panel wouldn’t slide out properly so someone used force and caused an impact of some of the components.
* Insufficient testing was done to confirm everything worked properly and the damaged module was eventually installed in Apollo 13.
* Pre-launch tests included filling all the cryogenic tanks, this worked fine. Next they had to empty all the tanks, this did not work fine. Evidently the drain line on this fuel cell LOX tank was damaged.
* Plan B to drain the tank was to turn on the electric heater and just boil off the excess LOX.
* The heater was specified to run on Apollo’s own low voltage power supply but a late change had it capable of running off the higher voltage power from the ground equipment.
* Technically the heater DID work on the higher voltage and it did heat the tank. But no one had tested if the thermostatic cutoff would work.
* The higher voltage welded the thermostats contacts together and meant the heater didn’t shut off from overheating and kept running on full power overnight
* The tank overheated massively, first boiling off the oxygen but then burning the insulation on the wires for the heater and for the fan
* No one knew the wires were damaged and launch went ahead as scheduled
* A few hours into flight, Kevin Bacon was told to “stir the tanks” i.e. activate the fans and mix the LOX and GOX.
* The damaged wires caused a fire which in the pure oxygen environment burned the insulation and blew up the tanks.
* Later changes to the Apollo Service Module design added redundancy in case of catastrophic electrical failure but the biggest change was not to bother with the fan to stir the tanks, turns out measuring unstirred tanks wasn’t as hard as they thought.
tl;dr It’s all Kevin Bacon’s fault.
Amazing video. Very detailed and the 25char
I loved this video. Def worth the background listen even if you know the story
This was such a great watch!