Spacewalking astronauts encountered leaking problems while trying to service the cooling system of the International Space Station (ISS) on Nov. 6. The out-of-this-world plumbing job that lasted for more than seven hours was done by American astronauts Scott Kelly and Kjell Lindgren.

Kelly and Lindgren spent exactly seven hours and 48 minutes working outside the ISS to repair its cooling system. During Friday's work, they encountered an ammonia leak and a minor glove damage while trying to locate the cooling problem.

Their main focus was to undo repairs made on the ISS's ammonia leak three years ago. Since the leak was fixed by replacing the defective pump, they were tasked to bring the radiator system back to its original setup.

Two hours into their work, Lindgren reported noticing small flakes of escaping toxic ammonia when he was isolating the primary cooling system from the backup one. They assured Mission Control that it appeared to be just a small leak and they were unharmed.

Ammonia can be very toxic to humans and any residue on the astronauts' space suits must be dissolved before going back inside the ISS. The compound would usually be removed in an ammonia reservoir, which vents out excess ammonia. This will reduce the risk of bringing the toxic substance inside the station. Kelly and Lindgren were outside long enough that the ammonia was no longer a threat. 

After checking their suits for any residue, Kelly noticed that the forefinger of his right glove had been damaged. Flight controllers ascertained that the damage was superficial.

The spacewalk, which was originally planned to last for six and a half hours, was slowed down by the problems the astronauts encountered. Because of the delay, Mission Control advised the space walkers to undo their radiator work, wasting their earlier effort.

Leaving the backup radiator extended should pose little risk for damage, NASA assured.

The spacewalk is the sixth one this year and the 190th in 17 years. The whole mission was broadcasted via live streaming. The ISS's Twitter account also gave enthusiasts live updates of the spacewalk.

"Going off grid for #spacewalk ... I'll be back w you again soon!" Kelly tweeted before his walk in space.

"Good work, Kjell and Scott. It's been my privilege working with you guys today," astronaut Megan Behnken said when she called from the mission control center. "You make us proud."

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