Space: ISS Cooling System Malfunction (Update)

[bystander]

Space Station Suffers Cooling System Malfunction
Space.com | Space Flight | 01 Aug 2010

The International Space Station suffered a cooling system malfunction late Saturday that forced its astronaut crew to power down some vital systems while engineers on Earth study the problem.

A power spike led to the shutdown of a pump module in one of two liquid ammonia cooling loops on the space station, setting off alarms that awoke the six astronauts living aboard the orbiting lab, NASA officials said in a statement. The malfunction occurred Saturday at about 8 p.m. EDT (0000 Sunday GMT) while the crew was sleeping.

Once awake, space station astronauts powered down some attitude control systems, as well as redundant communications and global position system gear to balance the heat loads on the outpost's backup cooling system, which is working well.

"The crew is in no danger, but will need to work additional troubleshooting on Sunday to keep the station in a stable configuration, including the installation of a jumper cable to maintain proper cooling to the Zarya module in the Russian segment," NASA officials said.

NASA Plans Emergency Spacewalks to Fix Space Station
Space.com | Space Flight | 02 Aug 2010

NASA is planning a pair of emergency spacewalks to repair the International Space Station after half of its cooling system shut down unexpectedly Saturday, forcing astronauts to power down several systems.

The two repair spacewalks will be performed by American astronauts Doug Wheelock and Tracy Caldwell Dyson and could begin Thursday to replace a pump module in one of the space station's two cooling system loops. Engineers are assessing the spacewalk plans before making a final decision.

"The crew is being informed that replanning for alternate spacewalk activity is underway," NASA officials said in a statement. A spacewalk had already been planned for Thursday for the Wheelock and Caldwell Dyson to upgrade some station systems.

NASA has stressed that Wheelock, Caldwell Dyson and the rest of the six astronauts living aboard the International Space Station are in no danger from the cooling system problem. But it is something Mission Control would like to address quickly since initial troubleshooting efforts have failed.

"An attempt overnight Sunday to close the circuit breaker and restart the Pump Module was not successful," NASA officials said. The space agency will give an update on the space station's status and spacewalk planning at 4 p.m. EDT (2000 GMT).

[owlice]

The International Space Station suffered a cooling system malfunction late Saturday that forced its astronaut crew to power down some vital systems while engineers on Earth study the problem.

Once awake, space station astronauts powered down some attitude control systems

Do these ensure the astronauts get along?

And are these systems available for household use, please?

[bystander]

Do these ensure the astronauts get along?

And are these systems available for household use, please?

I think they are meant to keep the space station stable, not the astronauts.

[owlice]

I think they are meant to keep the space station stable, not the astronauts.

The space station has attitude -- I like it, I like it!!

[neufer]

I think they are meant to keep the space station stable, not the astronauts.

The space station has attitude -- I like it, I like it!!

Attitude, n. [It. attitudine, LL. aptitudo, fr. L. aptus suited, fitted.]

1. (Paint. & Sculp.) The posture, action, or disposition of a figure or a statue.

2. The posture or position of a person or an animal, or
__ the manner in which the parts of his body are disposed;
position assumed or studied to serve a purpose; as, a threatening attitude; an attitude of entreaty.

3. (Figuratively) Position as indicating action, feeling, or mood.
-----------------------------------

<<The attitude (orientation) of the [International Space Station] is independently determined by a set of sun, star and horizon sensors on Zvezda and the US GPS with antennas on the S0 truss and a receiver processor in the US lab. The attitude knowledge is propagated between updates by rate sensors. Attitude control is maintained by either of two mechanisms; normally, a system of four control moment gyroscopes (CMGs) keeps the station oriented, with

• 1) Destiny forward of Unity,
  2) the P truss on the port side, and
  3) Pirs on the Earth-facing (nadir) side.

When the CMG system becomes 'saturated'—when the set of CMGs exceed their operational range or cannot track a series of rapid movements—they can lose their ability to control station attitude. In this event, the Russian attitude control system is designed to provide desaturating thruster firings, taking over automatically whilst the CMG system is reset. This automatic attitude control safing has only occurred once, during Expedition 10. When a space shuttle is docked to the station, it can also be used to maintain station attitude. This occurs during portions of every mated shuttle ISS mission. Shuttle control was used exclusively during STS-117 as the S3/S4 truss was installed.>>

Zvezda (Russian: Звезда, meaning "star"), DOS-8, is a component of the International Space Station (ISS). It was the third module launched to the station, and provides some of the station's life support systems, as well as living quarters for two crew members. It is the structural and functional center of the Russian portion of the station - the Russian Orbital Segment. Zvezda was launched on a Proton rocket on July 12, 2000 and docked with the Zarya module on July 26. The rocket used for the launch was one of the first to carry advertising; it was emblazoned with the logo of the fast food chain Pizza Hut, for which the company is reported to have paid more than US$1 million.>>

Click to play embedded YouTube video.

[owlice]

the manner in which the parts of his body are disposed

I thought there were laws governing the disposal of bodies, as I was under the impression that I broke one or more... well, never mind that; we're getting off-topic here. Back to the topic at hand, the text of the linked article has been changed; there's no mention of attitude now:

Station astronauts shut down two control moment gyroscopes (used to maintain the station's orientation in space without thrusters), some station power converters and command-routing equipment, and backup systems for the station's S-band communications antenna and Global Positioning System. So some station systems were running without backups in place if they fail.

[neufer]

Back to the topic at hand, the text of the linked article has been changed; there's no mention of attitude now:

Station astronauts shut down two control moment gyroscopes (used to maintain the station's orientation in space without thrusters), some station power converters and command-routing equipment, and backup systems for the station's S-band communications antenna and Global Positioning System. So some station systems were running without backups in place if they fail.

So they lost their attitude

[bystander]

... the text of the linked article has been changed; there's no mention of attitude now:

My bad, I put the same link for both articles. It's fixed now.

So they lost their attitude

No, they still have their attitude. Can't have the ISS losing attitude.

[bystander]

Graphic: ISS Cooling System Malfunction Explained
Space.com | Space Flight | 03 Aug 2010

Click to view full size image

A short circuit in a vital cooling system pump on the International Space Station has set the stage for two emergency spacewalks to replace the faulty component.

Each pump module weighs 780 pounds (353 kg) and is 5 1/2 feet long (69 inches) by 4 feet wide (50 inches). They are also about 3 feet tall (36 inches), making them very bulky and difficult to move.

Two pumps are used at any given time to run the space station's two U.S. cooling system loops: Loop A and Loop B. The failed pump is part of the Loop A system. The space station also has an independent Russian cooling system that can support the station on its own for a brief time, if required, station managers have said.

There are four spare pumps on the space station.

NOTE: This graphic does not portray all parts of the space station but rather focuses on those aspects related to the cooling system malfunction.

FAQ: ISS Cooling System Pump Failure
Space.com | Space Flight | 06 Aug 2010

Exactly what went wrong on the space station?
How does the space station's cooling system work?
How bad is the problem for the space station?
Did the failure endanger the space station crew?
How can astronauts replace the station's ammonia pump?
Doesn't it take weeks to plan a spacewalk? How was this response so fast?
How big are the station's ammonia pumps and how much do they cost?
What space station systems were affected by the pump's failure?
What happens if both U.S. cooling loops on the space station fail?
How large is the International Space Station?

Graphic: Inside and Out: The International Space Station

Spacewalking Astronauts Tackle Major Space Station Repair
Space.com | Space Flight | 07 Aug 2010

Two spacewalking astronauts ventured outside the International Space Station Saturday to begin a major repair job on the outpost's main cooling system.

Clad in their NASA spacesuits, American astronauts Douglas Wheelock and Tracy Caldwell Dyson floated outside the station at 7:19 a.m. EDT (1119 GMT) to replace a large oven-size pump that moves liquid ammonia through the right side of the orbiting laboratory's cooling system.

It is the first of two unplanned spacewalks the astronauts will take to complete the complicated space station repair. A second spacewalk is set for Wednesday.

Mission Update:

Astronauts Prepare for Spacewalk
07 Aug 2010 06:13 EDT

Space station crew members Douglas Wheelock and Tracy Caldwell Dyson have donned their spacewalking suits and are preparing to exit the station to replace an ammonia pump in the space station’s cooling system. The spacewalk is scheduled to begin at 06:55 EDT.

Preparations are running approximately 25 minutes behind schedule due to issues with a communications cap on Caldwell Dyson’s suit.

Astronauts Begin Spacewalk
07 Aug 2010 07:22 EDT

Two astronauts have opened a hatch on the space station and switched their spacesuits to battery power to begin the spacewalk to remove a failed pump module from the station’s cooling system. Astronauts Douglas Wheelock and Tracy Caldwell Dyson began about 25 minutes late, officially starting on Saturday at 07:19 EDT.

Spacewalkers Release Clamps
07 Aug 2010 08:21 EDT

Spacewalker Wheelock successfully released three clamps on the interior of the space station’s truss structure that hold the lines of ammonia fluid in place. Caldwell Dyson, who was preparing tool bags by the Quest airlock module, has also joined Wheelock on the truss structure.

Spacewalkers Keeping Good Time
07 Aug 2010 08:54 EDT

According to mission control in Houston, spacewalkers Wheelock and Caldwell Dyson are maintaining a good timeline on their tasks. Wheelock is about 10 to 15 minutes ahead, and Caldwell Dyson is about five minutes behind.

Wheelock is preparing to disconnect the ammonia lines and Caldwell Dyson is configuring a foot platform that she will later use to assist in the removal of the pump module.

Spacewalkers Set Up at Work Site
07 Aug 2010 09:51 EDT

The two spacewalkers have arrived at their work site on the space station's truss, near where they will remove the faulty ammonia coolant pump and replace it with a new model.

Doug Wheelock has attached a portable foot restraint platform on the end of the station's robotic arm, and is preparing to wedge his feet into it so the arm can carry him around like a crane.

Tracy Caldwell Dyson has likewise attached foot restraints on the truss so she can begin her work.

Astronauts Work to Disconnect Cables from Faulty Pump
07 Aug 2010 10:57 EDT

Spacewalkers Doug Wheelock and Tracy Caldwell Dyson are working to disconnect the umbilical lines from an ammonia coolant pump on the outside of the International Space Station. The pump broke last week, and the astronauts must disconnect all the cables attached to it before they can remove it and install a replacement.

As each cable is undone, the astronauts must restrain the lines with tethers to the station so they can reattach them to the new pump when it is installed.

Spacewalkers Work to Undo Stuck Cables
07 Aug 2010 11:48 EDT

Spacewalkers Doug Wheelock and Tracy Caldwell Dyson are still trying to undo the ammonia lines connecting the failed pump module to the space station. Wheelock is taking a short break after struggling to undo a stuck umbilical cable that is attached tightly. He will resume trying to release the line soon.

Spacewalker Disconnects Ammonia Line
07 Aug 2010 12:26 EDT

Spacewalkers Doug Wheelock has finally succeeded in disconnecting one of several liquid ammonia lines to be removed from the faulty space station pump. It came after lengthy delays trying to unhook the ammonia lines in order to remove the pump for today's spacewalk replacement work.

Today's spacewalk has passed the 5-hour mark and is slated to run about 7 hours.

Mission Control Discusses Options for Pump Repair
07 Aug 2010 13:36 EDT

NASA engineers are weighing their options for today's spacewalk after Wheelock reported a substantial amount of ammonia coming out of the last hose he tried to disconnect.

Today's spacewalk began at 7:19 a.m. EDT and was expected to last seven hours. The astronauts will need to spend some time cleaning their spacesuits now to make sure there is no ammonia contamination.

Spacewalkers Leave Ammonia Hose in Place
07 Aug 2010 14:18 EDT

Mission Control has ordered spacewalkers Doug Wheelock and Tracy Caldwell Dyson to leave the leaky ammonia hose in place on the faulty coolant pump they were working on. They will wrap up today's spacewalk and decontaminate their spacesuits to make sure no ammonia is carried inside the space station.

"It's clear that they won't be able to remove the failed pump from its place on the truss structure," a NASA commentator said.

Today's spacewalk began at 7:19 a.m. EDT (1119 GMT) and was expected to last about seven hours.

Spacewalkers Return to ISS Airlock
07 Aug 2010 14:56 EDT

Spacewalkers Doug Wheelock and Tracy Caldwell Dyson have returned to the Quest airlock at the International Space Station, where they are currently working through decontamination procedures to make sure they don't bring any ammonia coolant inside the space station from today's spacewalk.

[Beyond]

So apparently it is not fiesible to pipe the cold of space through the ISS to cool it down?

[Chris Peterson]

So apparently it is not fiesible to pipe the cold of space through the ISS to cool it down?

The temperature of the thin atmosphere around the ISS is a few thousand degrees. Space has no temperature, except to the extent that the particles traveling through it generally do. In order to cool the ISS using "space", you'd need radiator panels outside, shielded from the Sun, so that the heat would flow towards the cosmic background (in theory, around 3K, but in practice probably higher because of the geometry of the radiator).

[bystander]

Next Spacewalk No Earlier Than Wednesday
NASA | ISS Mission News | 07 Aug 2010

The next spacewalk to complete the removal of a failed ammonia pump module and installation and activation of a new pump module on the International Space Station’s S1 Truss will take place no earlier than Wednesday.

Expedition 24 Flight Engineers Doug Wheelock and Tracy Caldwell Dyson completed the first spacewalk to remove and replace the pump module at 3:22 p.m. EDT Saturday. As the result of an ammonia leak in the final line that needed to be disconnected from the failed pump module, the day’s tasks were only partially completed. The decision was made to reconnect the line on the pump module and install a spool positioning device to maintain proper pressure internal to the ammonia line.

Teams on the ground are evaluating the impact of the leak on plans to replace the failed pump, as well as possible fixes for the leak. The completion of the process will most likely require at least two additional spacewalks.

Saturday’s excursion lasted 8 hours, 3 minutes, making it the longest expedition crew spacewalk in history and the sixth longest in human spaceflight history.

Wheelock conducted the fourth spacewalk of his career. Caldwell Dyson made her first spacewalk. Flight Engineer Shannon Walker operated Canadarm2, the station’s robotic arm, and assisted the spacewalkers from inside the station.

After the loss of one of two cooling loops July 31, ground controllers powered down and readjusted numerous systems to provide maximum redundancy aboard the orbiting laboratory. The International Space Station is in a stable configuration, the crew is safe and engineers continue reviewing data from the failed pump.

Spacewalk Briefing Graphics

[bystander]

NASA Targets Wednesday For Next Space Station Repair Attempt
Space.com | Space Flight | 09 Aug 2010

NASA engineers are once again scrambling to find a way to restore the International Space Station's ailing cooling system back to full strength after weekend spacewalk repair efforts were stalled.
...
NASA engineers and mission managers spent all of last week planning Saturday's attempted spacewalk repair. The job was already so complicated that two spacewalks would be necessary, station managers said at the time.

Now, a third repair spacewalk will be required before Wheelock and Caldwell Dyson can completely replace the pump with a spare one and restore the space station's ammonia cooling system.

On Wednesday, the astronauts will have to disconnect two additional ammonia plumbing hoses elsewhere on the space station in order to staunch the leak that occurred when Wheelock initially tried to remove the faulty pump, Navias said. Once that work is complete, the spacewalkers will vent any remaining ammonia from the final ammonia hose, then disconnect it along with five support cables and bolts in order to remove the pump.
...
The disabled pump will be stored on the station's railcar-like Mobile Transporter system, Navias said.

"That's probably as far as we're going to get on Wednesday and that then would set us up for a Sunday spacewalk," Navias said.

It would be on Sunday that, if all goes according to plan, Wheelock and Caldwell Dyson would be able to retrieve the spare ammonia pump and install it, Navias added.

[bystander]

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.
...
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.
...
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.

[bystander]

NASA: 4 Spacewalks Needed to Complete Space Station Repairs
Space.com | Space Flight | 11 Aug 2010

NASA officials said Wednesday that astronauts will now have to perform four spacewalks in all – twice the number originally planned – to repair the International Space Station's ailing cooling system.

The announcement came just after American astronauts Douglas Wheelock and Tracy Caldwell Dyson successfully removed a broken ammonia pump from the space station Wednesday during their second spacewalk in five days to make the critical repairs.

Wheelock and Caldwell Dyson spent nearly 7 1/2 hours working to remove the oven-sized pump from the space station's right side. A third repair spacewalk, which was slated for Sunday, has been delayed to Monday morning, space station managers said.
...
There is no firm date yet for the fourth spacewalk, but it could occur late next week if space station astronauts do not complete the installation of a new pump on Monday.

If the new pump is successfully installed Monday, the fourth spacewalk would be dedicated to moving the broken pump to its final storage position. During Wednesday's spacewalk, spacewalkers parked the disabled pump in a temporary location.

[neufer]

Ἄμμων Ammon

<<Ammonia is better for the ISS than freon as it has a very high specific heat capacity = 4.7 J/(g·K). [Water = 4.18 J/(g·K).] It's usage is more analogous to a car radiator than to a refrigeration unit though, as there is no phase change (ie., vapor/liquid).>>

<<When it comes to fluids as coolant or heat transfer fluids, water and ammonia far and away are superior to any other fluids, and we use both of them on the Station. We use water inside the pressurized modules but it does have some drawbacks and one of them would be that it freezes at 32º Fahrenheit. Whereas ammonia doesn't freeze until we get to -108º Fahrenheit and we do see those extremes external to the pressurized modules and that is why we use ammonia.>>

<<The Romans called the ammonium chloride deposits they collected from near the Temple of Jupiter Amun (Greek Ἄμμων Ammon) in ancient Libya 'sal ammoniacus' (salt of Amun) because of proximity to the nearby temple. In the form of sal-ammoniac, ammonia was important to the Muslim alchemists as early as the 8th century, first mentioned by the Islamic chemist Jābir ibn Hayyān, and to the European alchemists since the 13th century, being mentioned by Albertus Magnus. It was also used by dyers in the Middle Ages in the form of fermented urine to alter the colour of vegetable dyes. In the 15th century, Basilius Valentinus showed that ammonia could be obtained by the action of alkalis on sal-ammoniac. At a later period, when sal-ammoniac was obtained by distilling the hooves and horns of oxen and neutralizing the resulting carbonate with hydrochloric acid, the name "spirit of hartshorn" was applied to ammonia. Gaseous ammonia was first isolated by Joseph Priestley in 1774 and was termed by him alkaline air. The Haber-Bosch process to produce ammonia from the nitrogen in the air was first used on an industrial scale by the Germans during World War I, following the allied blockade that cut off the supply of nitrates from Chile. The ammonia was used to produce explosives to sustain their war effort.>>

[bystander]

ISS Astronauts Tackle Third Spacewalk to Fix Cooling System
Space.com | Space Flight | 16 Aug 2010

Two spacewalking astronauts ventured outside the International Space Station Monday on another big repair job to install a vital new pump and restore their ailing cooling system back to full strength for the first time in two weeks.

It is the third of four repair spacewalks for NASA astronauts Douglas Wheelock and Tracy Caldwell Dyson, who plan to spend at least 6 1/2 hours installing the new ammonia coolant pump. The astronauts removed a faulty pump during an earlier spacewalk on Aug. 11.
...
Monday's spacewalk began at 6:20 a.m. EDT (1020 GMT), about 35 minutes ahead of time, NASA spokesperson Rob Navias said during televised commentary. The astronauts swiftly tackled their first chore: removing the new pump from a spare parts platform on the station's exterior.
...
Space station managers hope Wheelock and Caldwell Dyson will be able to completely hook up the new pump during Monday's spacewalk. The astronauts removed the faulty ammonia pump over two previous spacewalks (on Aug. 7 and Aug. 11) and are expected to install to perform a fourth spacewalk to move the disabled pump to its final storage location.

Mike Suffredini, NASA's space station program manager, said Monday's spacewalk – or extravehicular activity in NASA parlance – would go as long as possible to complete as much work as possible.

Mission Update | Courtesy: NASA TV

Astronauts Begin 3rd Repair Spacewalk
16 August 2010 06:31 EDT

Spacewalkers Douglas Wheelock and Tracy Caldwell Dyson have officially begun the third spacewalk dedicated to the repair of the International Space Station's cooling system.

The spacewalk began at 6:20 a.m. EDT (1020 GMT), about 35 minutes ahead of scheduled. Today's big chore: the installation of a new oven-sized ammonia coolant pump to replace a faulty pump that was removed on Aug. 11 by the spacewalkers.

Spacewalkers Retrieve Spare Ammonia Pump
16 August 2010 07:19 EDT

Spacewalker Douglas Wheelock and Tracy Caldwell Dyson are working to retrieve the spare ammonia pump they'll be installing today on the International Space Station.

The pump has been stored on an equipment platform since 2006. Caldwell Dyson is floating free, while Wheelock is riding the space station's robotic arm. NASA astronaut Shannon Walker is controlling the arm from inside the space station.

Astronaut Moves New Station Pump Into Place
16 August 2010 08:21 EDT

Spacewalker Douglas Wheelock, perched at the tip of the International Space Station's robotic arm, is hauling the spare 780-pound ammonia pump into position on the right side of the outpost. Crewmate Tracy Caldwell Dyson is helping with orientation calls while astronaut Shannon Walker controls the arm from inside the space station.

"You know, when you're on the [spare parts platform] looking down at the Earth like this, it's like extreme hang gliding," Caldwell Dyson said.

One of four bolts securing the pump in place gave Wheelock some trouble when it refused to budge, but some extra elbow grease and tools did the trick.

"Come on now, bolt," Wheelock said as he freed the stuck bolt. "Turning! Sweet!"

Spacewalkers Move Station's New Coolant Pump Into Place
16 August 2010 08:53 EDT

Spacewalkers Douglas Wheelock and Tracy Caldwell Dyson have successfully moved the International Space Station's spare 780-pound ammonia pump into position on the right side of the outpost. You can watch the action LIVE on NASA TV.

"Okay, I think we're in there," Wheelock said.

"Outstanding," one of the other astronauts replied.

The pump will be bolted in place with four bolts, then four ammonia hoses and five electrical connections will be made to plug into the space station's systems.

Spacewalkers Wire Up New Space Station Pump
16 August 2010 09:35 EDT

Spacewalkers Douglas Wheelock and Tracy Caldwell Dyson attached five power and data cables to the space station's new coolant pump. Mission Control has verified the pump is working.

Spacewalkers Attach Ammonia Hoses to New Pump
16 August 2010 10:20 EDT

Spacewalkers Douglas Wheelock and Tracy Caldwell Dyson are tackling work to attach four liquid ammonia hoses to the space station's new cooling system pump.

"We hope to have a pump back for you commander," Wheelock told space station commander Alexander Skvortsov. Today's spacewalk is approaching the 4-hour mark. It began at 6:20 a.m. ET.

Space Station Ammonia Pump Hoses Hooked Up
16 August 2010 10:20 EDT

Spacewalkers Douglas Wheelock and Tracy Caldwell Dyson have successfully hooked up all four ammonia hoses to the new pump module they installed on the right side of the International Space Station. You can watch the action LIVE on NASA TV.

The milestone occurred about 4 hours and 20 minutes into today's spacewalk, which began at 6:20 a.m. ET and is expected to last about 6 1/2 hours.

Spacewalkers Complete Ammonia Pump Replacement
16 August 2010 11:20 EDT

Spacewalkers Douglas Wheelock and Tracy Caldwell Dyson have completed their main goal for today's spacewalk: Replacing a vital coolant pump on the starboard side of the International Space Station.

It took three spacewalks to complete. The new pump replaces one that failed July 31. The astronauts performed spacewalks on Aug. 7 and Aug. 11 to remove the faulty pump. Today, installed the new oven-sized pump, attached 5 power and data cables and hooked up 4 ammonia hoses to complete the repair. The pump is now being filled with liquid ammonia coolant. Tests are scheduled to begin on Tuesday.

Spacewalkers Collect Tools From Repair Work
16 August 2010 12:50 EDT

With their main goal complete, astronauts Douglas Wheelock and Tracy Caldwell Dyson are going through the meticulous process of collecting all of the tools they used during today's spacewalk repair.

Today's spacewalk is nearing the 6 1/2-hour mark, with engineers on Earth working to see if they have time for an extra chore to wire up a power extension cord – a chore needed to prepare the station for an upcoming NASA shuttle mission. Today's spacewalk began at 6:20 a.m. ET.

No Extra Chores for Spacewalking Astronauts
16 August 2010 13:20 EDT

Mission Control has decided that astronauts Douglas Wheelock and Tracy Caldwell Dyson will not tackle any extra chores during their spacewalk today outside the International Space Station.

The decision comes after a close look at the astronauts' oxygen supplies, which were just on the edge of acceptability for an extra task. It will be added to future spacewalk.

Astronauts Complete 3rd Repair Spacewalk
16 August 2010 13:50 EDT

NASA astronauts Douglas Wheelock and Tracy Caldwell Dyson have completed their third repair spacewalk at the International Space Station.

The astronauts installed a new cooling system pump in what NASA officials have called one of the most challenging space station fixes in its 12-year history.

Total spacewalking time: 7 hours, 20 minutes. Today's spacewalk began at 6:20 a.m. EDT and was the third in nine days to replace a faulty ammonia cooling system pump that failed July 31. A fourth spacewalk is expected to be scheduled later to move the broken pump to its final location on the space station. It is currently in a temporary spot and took two spacewalks to remove.

Success In Orbit: Astronauts Replace Vital Space Station Cooling Pump
Space.com | Space Flight | 16 Aug 2010

Two space station astronauts hit pay dirt in orbit Monday after successfully replacing a vital pump to restore their spacecraft's cooling system, which has been limping along at half-power for more than two weeks.

Astronauts Douglas Wheelock and Tracy Caldwell Dyson wired up a bulky ammonia pump the size of a kitchen oven into the right side of the space station during the hours-long spacewalk. It was the third spacewalk for the astronauts to make the tricky repair 220 miles (354 km) above Earth. A fourth spacewalk is planned for later to clean up some final work.

"Game over!" Wheelock said as they wrapped up the pump replacement work. Mission Control used remote commands to start filling the pump with liquid ammonia and plans to start testing it on Tuesday.

[bystander]

NASA Revives Space Station Systems After Tricky Repairs
Space.com | Space Flight | 17 Aug 2010

NASA is steadily reviving systems on the International Space Station following a series of complicated spacewalks to repair its vital cooling system.

Flight controllers on Earth are reactivating some systems for the first time since July 31, when an ammonia coolant pump failure knocked out half of the space station's cooling system. The station's astronaut crew replaced the faulty pump in three spacewalks, with the most recent one on Monday.
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With the repairs complete, station flight controllers are methodically restarting many of the systems that were placed offline. These include the electrically-driven gyroscopes that help maintain the station's attitude, and the second string of electronics for the space station's robotic arm.
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Scientific research was stalled as well, though mission planners are taking a close look at what experiments may be salvaged in the weeks ahead.
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At the moment, station managers predict that the space station should be fully operational – as it was before the incident occurred – by Thursday.