The International Space Station
(USA TODAY) -- Laboratories in the U.S. portion of the International Space Station
are running at full power again, officials said Thursday, after a pair
of spacewalks to repair a partially failed cooling system.
in Houston worked through Christmas Day to activate a new coolant pump
installed during the second spacewalk on Tuesday, and to integrate it
with equipment that transfers heat generated inside the outpost to giant
That allowed normal operations to resume in
the U.S. Destiny and Japanese Kibo labs and two connecting modules. Only
the European Space Agency's Columbus lab hasn't yet been fully powered
"Everything is working perfectly now," NASA TV
commentator Kelly Humphries reported during a regularly scheduled
update. "Cooling Loop A is looking great."
Loop "A" is one of two
running outside the station. The Dec. 11 failure of a valve in an
ammonia pump module that regulated the loop's temperature caused it to
get too cold.
That created a risk that water from the internal
cooling system could freeze and expand, potentially cracking heat
exchangers and allowing highly toxic ammonia inside the six-person
crew's living area.
Non-essential systems inside were shut down
for about two weeks, while the station operated with one of its cooling
loops. That left it more vulnerable to a second failure, a situation
NASA didn't want to see continue for long.
NASA astronauts Rick
Mastracchio and Mike Hopkins performed spacewalks on Saturday and
Tuesday to remove the faulty pump and install one of three available
They rested on Christmas Day while the ground teams restored the second cooling loop without incident.
Russian cosmonauts Oleg Kotov and Sergey Ryazanskiy will head outside
for the year's 11th and final ISS spacewalk, a planned seven-hour
excursion to update experiments and install cameras.
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