Skylab II power failures

A series of power failures have occurred within the first four years of the launch of the Skylab Workshop Station. The first failure occurred on January 24th 1977 (108 days after the launch), and followed by two more failures on July 9th 1978 and November 12 1981. The blackouts have caused serious disruption to the operation of the station, and cost the space agency $32 million of science time and space resources. All three failures to date were identified to be caused by one common problem: fuel cell issues.

## Background and Events

Before the fuel cell and solar array upgrade missions in December 1981, Skylab II relied on two relatively small solar arrays and one medium-large fuel cell for electrical power, which later proved to be insufficient and too stressful for the station's electrical demand. Both the fuel cells and station flight batteries' systems are linked together. The power failures all occurred when the station orbited into the Earth's shadow (where the electrical supply via solar panels is not active). The duration of the blackouts lasted from 47 minutes to six days.

### Power failure on Jan 24 1977

At 7:43 pm EST, while the crews of Expedition 2 and 3 were finishing up dinner and watching a movie, fuel cell number 1 overheated (due to the electricity demand of all the computers, lights and station equipment) and subsequently failed. This triggered a surge of battery power discharge, which activated a safety switch which shut down all the power on the station to prevent a deadly electrical fire. Everything inside the station went black and silent, startling the crew. With the exception of isolated power systems for mission control contact, the crew radioed for help of the problem.

Mission control in Houston identified the problem to be a blown fuse caused by overload, and instructed Thomlo Kerman, commander of Skylab on Expedition 1/2 to go on EVA to repair it. The repair lasted 4 hours and 12 minutes. In that time the ambient internal temperature inside the station (without the heating system working) dropped down dramatically to -3oC, causing cold discomfort, especially among the Brazilian and Spanish astronauts aboard. The crew spent hours mopping up condensation and ice on the station walls and windows, and some put on their spacesuits and flight suits to stay warm.

Eventually the faulty fuel cell was fixed at 11:55 pm, restoring power once again. Gene Kranz obviously wasn't happy with the manufacturer of the fuel cell at Nebula Engineering systems, who failed to notify him and SSPX about the inevitable power demand problems beforehand.

### Power failure on July 9 1978

1 year, 5 months and 15 days after the first failure, the replacement fuel cell fuse eventually blew due to overheating, causing yet again another blackout on the station. This time it occurred at 4:37 am EST while the crew of Expeditions 4 and 5 were sleeping. This blackout was fortunately the shortest of the three failures so far, lasting no more than 41 minutes. In fact the rest of the 114 sleeping crew didn't feel the surge as it happened relatively quietly, except Raphael J. Chryslar (who was on his first long term mission in space). An alarm in his sleeping quarter in the Habitation segment sounded, where he woke out of bed and floated towards the airlock to put on a spacesuit. He ventured outside of the station alone (with a spare fuse that was brought up via Cygnus 2) and replaced it once again within 30 minutes.

After the repair, he radioed Houston about the resolved situation and asked the team to come up with a long term solution to prevent further failures. While in his spacesuit, Chryslar paused while holding to a handle on the workshop, and overheard Gene Kranz snapping at two employees via the CAP-COM microphone in the background, when they suggested estimates about the time it will take to develop and launch the new power supply systems for Skylab. He then overheard that Gene wanted the procedures right now, and that he will have the man (who was responsible for the manufacturing of the fuel cell at Nebula Engineering) dishonorably fired if the new part fails.

Chryslar then fitted a temperature sensor to the fuse (to warn of any future failures), returned to the station via the airlock, doffed his suit and returned to bed. He later woke up at 8 am a bit late, only to find the newly woken crew puzzled at why all the computers and printers on the station have rebooted. Chryslar and Chris Hadfield announced on the intercom telling the crew about the second power failure hours earlier.

### Power failure on November 12, 1981

The next 852 days of Skylab station operations passed flawlessly and without major interruptions (except a minor microwave fuse pop). After the first 7 days of repairing the fuel cell on July 9 1981 passed without problems, the crew decided to lower their guard on watching out for fuel cell overheating, as the temperature sensor gave a smooth reading. Nearly two and a half years passed without incident, and it was seemingly conclusive that the problem was fully solved at last.

But at 5:57 pm on November 12 1981, the 146 kerbals of Expeditions 6, 7 and 8 were in the midst of preparing meals for dinner, as well as making preparations for a Thanksgiving party in two weeks time. Some were busy cooking, heating and dishing up delicious meals, while others were finishing up science experiments, games and general Earth observations and personal conversations; when suddenly a small explosion, followed by a violent power surge and failure happened! This scared all the kerbals and caught them off guard. The first thing Raphael Chryslar said "*Damn, this flipping problem was finally fixed, HOW COULD THIS HAPPEN AGAIN!!!*".

The blackout was so severe it knocked out radio communications with ground control, leaving Houston panicking and unaware of what's going on in orbit. The explosion from the fuel cell's catastrophic failure has sent the station into a slow spin, which moved the solar arrays out of alignment with the sun. The 130 kerbals aboard was in shock, especially being caught off guard during a routine dinner aboard Skylab. Without communications with the ground, Terry Virts (commander of Expedition 6) initiated emergency procedures to not only restore power once more, but also stop the slow spinning of the station.