ISS Astronauts Take 2nd Spacewalk to Make Repairs
Space.com | Space Flight | 11 Aug 2010
A pair of astronauts floated outside the International Space Station Wednesday to once again try to remove a faulty – but crucial – coolant pump during the second in a series of complicated spacewalks to replace the device.
NASA astronauts Douglas Wheelock and Tracy Caldwell Dyson ventured outside the space station at 8:27 a.m. EDT (1227 GMT) on what they expect to be a six-hour job to remove the disabled pump, which is about the size of a kitchen oven.
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During this spacewalk, Wheelock and Caldwell Dyson will close two valves in hoses upstream of the pump in an attempt to stop the leak. They'll also vent any remaining ammonia coolant overboard before removing the last of four ammonia hoses from the faulty pump.
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Wheelock and Caldwell Tyson don't plan on completing their space station repairs during Wednesday's spacewalk. That comes on Sunday, when the astronauts plan to perform a third spacewalk to retrieve a spare pump from a storage platform and install it in the old pump's place, station officials have said.
Mission Update
Astronauts Gear Up for Second Repair Spacewalk
11 Aug 2010 07:06 EDT
Expedition 24 Flight Engineers Doug Wheelock and Tracy Caldwell Dyson are preparing to take a second spacewalk aimed at repairing the space station's broken ammonia coolant pump. The astronauts are donning their white EMU spacewalking suits and will soon begin depressurizing the airlock.
The spacewalk has been delayed about an hour and a half past its intended start time. They will likely begin at about 8:30 a.m. EDT today.
Astronauts Begin Depressurizing Airlock for Spacewalk
11 Aug 2010 07:58 EDT
The astronauts inside the space station's Quest airlock have begun to depressurize the room in preparation for opening the hatches and stepping out into space. The process should take about half an hour.
HATCHES OPEN! Spacewalk Begins
11 Aug 2010 08:29 EDT
Astronauts Doug Wheelock and Tracy Caldwell Dyson have switched their spacesuits to battery power and officially begun their spacewalk – the second aimed at replacing a broken ammonia coolant pump on the space station. The spacewalk officially begun at 8:27 a.m. EDT (1227 GMT).
"Sunlight – sunlight coming out," Wheelock said as he looked out of the station's open hatch.
"Wow, that's nice and bright," Dyson responded.
Spacewalkers Set Up at Work Sites
11 Aug 2010 09:25 EDT
The spacewalkers are gathering their tools and moving toward their work sites to take up the job of disconnecting a failed ammonia coolant pump on the outside of the International Space Station.
First, they will work to isolate an ammonia line leading to pump module to configure the pump to be demated from its perch on the station's truss. Tracy Caldwell Dyson is moving a tool cart from the S1 to S3 truss segments, while Doug Wheelock is collecting a tool bag he will need before riding aboard the station's robotic arm to his work site at the pump
Spacewalker Works to Disconnect Cable
11 Aug 2010 10:06 EDT
Spacewalker Doug Wheelock has successfully closed the quick-disconnect valve on a cable attached to the broken ammonia coolant pump, in preparation to remove the cable and then the failed pump. He will now work to disconnect the cable.
Spacewalkers Finally Disconnect Stubborn Cable
11 Aug 2010 10:30 EDT
Spacewalker Doug Wheelock managed to successfully de-mate the stubborn M3 cable on the station's broken ammonia coolant pump. The cable had refused to come loose during a previous attempt to disconnect the pump during last Saturday's spacewalk. A combination of brute force and measures taken to relieve the pressure in the line enabled Wheelock to finally release the connection.
"This will allow us to get our station back," Wheelock said. "Back in action."
Spacewalkers Check Spacesuits
11 Aug 2010 11:02 EDT
Spacewalkers Doug Wheelock and Tracy Caldwell Dyson inspected their spacesuits for any sign that ammonia coolant had leaked onto them, and luckily found them in good condition to press forward with the spacewalk.
The spacewalkers are now working to remove the bolts holding down a broken ammonia pump that they plan to remove from the space station.
Spacewalkers Progressing Ahead of Schedule
11 Aug 2010 11:21 EDT
Spacewalker Doug Wheelock has removed four bolts attached to the broken ammonia pump. Wheelock will now work to attach a high-tech adjustable handle to the pump module that will allow the spacewalkers to transfer it from the station's truss to a temporary stowage bracket.
Tracy Caldwell Dyson successfully removed five electrical and data connections from the broken ammonia pump.
"My dad would be proud," Caldwell Dyson said.
The crew is working efficiently and the spacewalkers are progressing ahead of schedule.
Spacewalkers Trying to Remove Pump Module
11 Aug 2010 12:28 EDT
Spacewalker Doug Wheelock has retrieved the adjustable grapple bar that will be used to maneuver the failed pump module from its slot on the station's truss.
Despite being ahead of the spacewalk timeline, there does not appear to be enough time during this outing to retrieve the replacement pump module from its location near the Quest airlock, said NASA commentator Rob Navias. The spacewalkers are, however, expected to accomplish a significant amount of the preparation work ahead of the third spacewalk.
Spacewalkers Struggling to Attach Handle to Pump Module
11 Aug 2010 13:12 EDT
The spacewalkers are struggling to attach an adjustable handle to the failed pump module that will allow them to extract the component from its position on the truss. Wheelock and Caldwell Dyson have been working longer than predicted in securing pins into receptacles on either side of the pump.
Failed Pump Module Removed from Station's Truss
11 Aug 2010 13:27 EDT
The spacewalkers have finally removed the failed pump module from its slot on the space station's truss.
Once the broken pump module is mounted and latched into place on a stowage bracket on the truss, Wheelock and Caldwell Dyson will move to where the replacement pump module is located to begin preparations for its eventual removal during a third spacewalk, currently targeted for Sunday.
Broken Pump Module Stowed
11 Aug 2010 14:13 EDT
Spacewalker Wheelock maneuvered the failed ammonia pump module onto a stowage platform on the space station's truss. Wheelock was assisted by crewmember Shannon Walker, who operated the robotic arm with from inside the station.
The removal and stowage of the pump module marks the completion of the main objective for today's spacewalk, NASA officials said.
Wheelock and Caldwell Dyson will now begin preparations for the third spacewalk, which is scheduled to occur no earlier than Sunday. The spacewalkers are expected to release three electrical connections and remove a series of bolts on the replacement module to prepare for its eventual removal and installation during the third spacewalk.
Spacewalkers Prepare New Pump Module for Installation
11 Aug 2010 14:50 EDT
The two spacewalkers are working to prepare the replacement pump module to be installed in a future spacewalk. They are undoing a few bolts and configuring the spare part to be moved into place and attached to the space station. After a few more preparatory jobs, they plan to wrap up and head back to the hatch.
Spacewalkers Inspect Spacesuits
11 Aug 2010 15:25 EDT
Caldwell Dyson and Wheelock are inspecting their spacesuits briefly to make sure they did not get any toxic ammonia on them that could be brought back inside the space station.
Astronauts End 2nd Repair Spacewalk
11 Aug 2010 15:53 EDT
The two spacewalkers are back inside the space station's airlock with the hatch closed, officially ending the spacewalk at 3:53 p.m. EDT. It was the second of three aimed at replacing a broken ammonia coolant pump on the station.