The space agency never before staged such a fast, impromptu spacewalk for a station crew. Even during the shuttle program, unplanned spacewalks were uncommon.
The ammonia pump was the chief suspect going into Saturday’s spacewalk. So it was disheartening for NASA, at first, as Cassidy and Marshburn reported nothing amiss on or around the old pump.
“All the pipes look shiny clean, no crud,” Cassidy said as he used a long, dentist-like mirror to peer into tight, deep openings.
“I can’t give you any good data other than nominal, unfortunately. No smoking guns.”
Engineers determined there was nothing to lose by installing a new pump, despite the lack of visible damage to the old one. The entire team — weary and stressed by the frantic pace of the past two days — gained more and more confidence as the 5 1/2-hour spacewalk drew to a close with no flecks of ammonia popping up.
“Gloved fingers crossed,” space station commander Chris Hadfield said in a tweet from inside. “No leaks!” he wrote a half-hour later.
Flight controllers in Houston worked furiously to get ready for Saturday’s operation, completing all the required preparation in under 48 hours. The astronauts trained for just such an emergency scenario before they rocketed into orbit.
This area on the space station is prone to leaks.
The ammonia coursing through the plumbing is used to cool the space station’s electronic equipment. There are eight of these power channels, and all seven others are operating normally.
Life for the six space station residents has been pretty much unaffected since Thursday’s ammonia shower. The loss of an additional power channel, however, could threaten science experiments and backup equipment.
“We may not have found exactly the smoking gun,” Cassidy said, “but to pull off what this team did yesterday and today, working practically 48 straight hours, it was a remarkable effort on everybody’s behalf.”