Astronauts make third space foray to fix ISS cooling pump

Astronauts from the International Space Station today conducted a third spacewalk to replace a busted cooling unit on the orbiting outpost, NASA said.

Last Updated: Aug 17, 2010, 00:10 AM IST

Washington: Astronauts from the
International Space Station today conducted a third spacewalk
to replace a busted cooling unit on the orbiting outpost, NASA
said.

Spacewalkers Doug Wheelock and Tracy Caldwell Dyson began
their work on installing a spare ammonia pump module on the
ISS at 6:20 am (local time) according to the US space agency,
which said the spacewalk would last a total of about six and a
half hours.

Flight Engineer Shannon Walker assisted the effort from
inside the ISS by operating the station`s robotic arm.

Space officials said Wheelock carefully positioned the
spare pump so that it could be securely bolted into place by
Caldwell Dyson and that four and a half hours into the
spacewalk, all fluid lines on the new unit were successfully
connected, with no detectable ammonia leaks.

The cooling unit`s nearly 800-pound (360 kilo) ammonia
pump failed unexpectedly on July 31 and was removed from the
USD 100-billion orbiting station during a spacewalk last
Wednesday.

The pump is critical to keep the station from
overheating. The six-member crew has relied on a single backup
since the malfunctioning pump failed during a power surge.

The incident set off alarms onboard the station, although
officials have said that crew of three Russians and three
Americans were never seriously in danger.

A first spacewalk to begin repairs on the malfunctioning
cooling system took place on August 7 and lasted a record
eight hours, three minutes, with a follow-up second spacewalk
on August 11.

PTI