During a fourth spacewalk Saturday to wrap up repairs of the coolant system in a $2 billion cosmic ray detector, Italian astronaut Luca Parmitano and Drew Morgan discovered a leak in one of eight coolant lines that were spliced into a new pump module during three earlier excursions.
NASA astronaut Drew Morgan and European Space Agency astronaut Luca Parmitano spent 6 hours, 16 minutes working outside station to finish repairs on the ailing Alpha Magnetic Spectrometer, a 9-year-old cosmic ray detector designed to seek out dark matter and antimatter. The instrument, launched in 2011, had lost two of four critical coolant pumps, which the spacewalkers restored. NASA aims to run a series of tests in upcoming days to make sure the repair worked.
It wasn’t an easy job to perform. Parmitano and Morgan were on the fourth of four spacewalks to fix AMS, completing work that began on the instrument in November. The astronauts were using tools to fix an instrument that was initially, never even designed for spacewalking repairs. On this spacewalk, which was broadcast live on NASA Television, leak drama dominated the early hours of the work.
The first leak happened even before astronauts left the space station airlock.
Shortly after NASA astronauts Christina Koch and Jessica Meir buttoned down the interior hatch, the crew discovered extraneous airflow during depressurization to let the spacewalking astronauts go “outside” into space. “It seems we may have a leak in the upper right corner. We can hear the airflow,” Meir reported to the ground as she hovered at the hatch.
Squeezed inside the airlock on the other side of the hatch, Parmitano spotted the problem in seconds: a strap from one of the tool bags was caught between the crew lock section (where the spacewalking astronauts were waiting to exit) and the equipment lock, where Meir and Koch were working on the inside of the station in the Unity module. The crew carefully repressurized the airlock, opened the hatch, checked the seal, and then closed the hatch again to restart depressurization. With no leaks happening this time around, Meir finished venting the airlock’s oxygen into space.