Two Russian astronauts floated outside the International Space Station on Wednesday and isolated the leaking coolant as planned, apparently causing the remaining coolant trapped inside to make its way to the leak site and blast off into space.
Cosmonaut Oleg Kononenko planned to soak up the coolant with a cloth towel, but was asked to leave the area immediately when he reported that some of the liquid had reached the safety rope. He said no one reached his claim.
The tether was secured in a bag and procedures were already in place to ensure that the astronauts’ suits were free of any such contamination before they re-entered the space station at the end of the spacewalk.
Meanwhile, Kononenko and his colleague Nikolai Chub continued to work on attaching a small synthetic aperture radar antenna to the Nauka module’s chassis. One of its four panels failed to fully deploy and lock into place, and officials said modifications will be made on future spacewalks.
Finally, Kononenko and Chubb launched a small, student-built “nanosatellite,” but the solar sail propulsion system they were designed to test failed to deploy. After making a final attempt to hold the faltering radar panel in place, the astronauts gave up.
Kononenko, who made his sixth spacewalk, and Chubb, who made his first, began the journey at 1:49 p.m. EDT when they opened the side door of the Poisk airlock to the vacuum of space.
The coolant in question was launched with Russia’s Rasvet module aboard the space shuttle Atlantis in May 2010. The cooler and the experiment’s small airlock remained stored at Rasvet until earlier this year when astronauts on a spacewalk attached them to the Naoka Laboratory Multipurpose Module.
The radiator was installed normally and the valves were opened to direct Nauka coolant to its exposed panels. But on October 9, flight controllers noticed flakes streaming from the radiator area. The flakes turned out to be frozen coolant that had been dumped into the sea.
Kononenko and CHUB inspected and reset the cooling loop valves, adjusted them to isolate the radiator from the supply lines and photographed the location of the leak to help engineers figure out what was causing it.
“The radiator is clean. I don’t see anything…I don’t see any traces of coolant,” Kononenko initially reported.
But he reported several “black spots” on one of the radiator panels and after adjusting the valves used to isolate the radiator from its cooling lines, drops of coolant could be seen leaking from the line connecting the two radiator panels.
The drops combine to form a fairly large bubble around the leaking coolant line. Kononenko said the bubble was too large to be absorbed by the towel he intended to use. Instead, the astronauts simply left it as it was while engineers on Earth began to consider possible courses of action.
What might have caused the cooling line to rupture in the first place was not immediately known.
It was the third coolant leak for the Russians in less than a year, starting with the massive rupture that disabled a Soyuz-crewed ferry ship last December. A similar leak occurred on an unmanned Progress bulk carrier earlier this year.
The presumed cause of the Soyuz leak was micrometeoroid impact. The Russians have not addressed the possible cause of the advance leak or the cause affecting the Nauka radiator. But it seems unlikely that micrometeorites could have caused three such incidents in similar systems.
However, shortly after the latest leak, Russian space agency Roscosmos said in a post on Telegram that the lab’s core cooling loop was unaffected and that “the crew and station are not in any danger.”
Kononenko and Chub were not planning any kind of reform. Their primary goal was to find where the leak originated, document it, and isolate the coolant from the coolant supply lines to prevent any future problems.
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