News Space Station suffers Coolant loop issue

[Orbinaut Pete]

NASASpaceFlight: "ETCS Pump Module changeout success following epic ISS EVA".

Florida Today's "The Flame Trench" Blog: "Station coolant system back in business after third spacewalk".

Tracy & Doug will probably do one more EVA to install a PDGF on of FGB, and install a cable on Node 1 for the PMM.
This means that Tracy will have some nice EVA experience for an assignment to STS-135! :thumbup:

---------- Post added at 08:18 PM ---------- Previous post was at 07:36 PM ----------

Spaceflight Now: "Spacewalkers complete space station cooling repairs".

BBC News: "Space station crew replace pump on third spacewalk".

Downloadable video of the EVA.

Downloadable video of the post-EVA briefing.

 

[astrosammy]

[...]for an assignment to STS-135![...]

:woohoo:

 

[Orbinaut Pete]

From ISS On-Orbit Status Report for 16/08/2010:

Stage EVA-17 by FE-2 Tracy Caldwell-Dyson & FE-4 Doug Wheelock was completed successfully in 7 hours 20 minutes, fully accomplishing its objective of installing the spare ETCS (External Thermal Control System) Loop A PM (Pump Module) plus additional tasks. The PM has been checked out and is functioning nominally. Loop A will be fully in service later this week. This was the third contingency spacewalk to replace the Loop A ammonia pump.

During the excursion, Doug (EV-1) & Tracy (EV-2), supported by FE-5 Fyodor Yurchikhin as IV (Intravehicular crewmember) plus FE-6 Shannon Walker & CDR Alexander Skvortsov on the SSRMS (Space Station Remote Manipulator System):
• Installed the spare PM mechanically.
• Mated & opened associated fluid QDs (Quick Disconnects).
• Successfully performed electrical & data continuity checks plus bump-start test (by MCC-H, verifying pump functionality).
• Re-coupled the Starboard & Port CETA carts.
• Cleaned up spare PM/S1/CETA (Crew Equipment Translation Aid) cart.
• Cleaned up the SSRMS by removing the APFR (Articulating Portable Foot Restraint) to enable SSRMS walkoff.
• Cleaned up tethers at S1 Truss.
• Configured the CETA cart to allow for WS-8 (Worksite-8) ops.
• Cleaned up/Ingressed the A/L (Airlock).

[EV-1 & EV-2 began their "campout" last night in the US A/L with hatch closure and depressurization of the CL (Crew Lock) from 14.7 to 10.2 psi at ~7:55 PM GMT for 70 minutes of mask prebreathe with O2 (oxygen). Following the usual hygiene break/with mask prebreathe for Tracy & Doug this morning at ~6:35 AM to 7:45 AM GMT, the A/L hatch was closed again by Shannon & Fyodor for EVA preps in 10.2 psi, followed by EMU purge and prebreathe in the EMUs. Afterwards, with CL depressurization and EV-1/EV-2 switching to suit power, EVA-17 began at 10:20 AM GMT, ~35 minutes ahead of timeline. It ended at 5:40 PM GMT, lasting 7 hours 20 minutes. It was the 150th spacewalk for ISS assembly & maintenance, the 14th this year, and the 242nd for US astronauts, with a total time of 944 hours 24 minutes.]

Before the EVA, Shannon:
• Verified closure of protective window shutters in Lab, JPM and Cupola.
• Completed the IV (Intravehicular) portion of the EVA "inhibit pad", i.e., the list of temporary external deactivations in support of the EVA.
• Set up the Lab RWS (Robotic Workstation) and DOUG (Dynamic Onboard Ubiquitous Graphics) peripherals with the SSC-8 (Station Support Computer-8) T61p laptop, to support SSRMS ops.
• Operated the SSRMS, "flying" Doug during the EVA.

During the spacewalk, Alexander assisted Shannon on the SSRMS, and Fyodor worked with her in supporting the Campout, prebreathe, EVA prep, EVA inhibit pad ops. & post-EVA activities.

Fyodor also configured the internal RS (Russian Segment) STTS communications connections for the EVA.

After ingress from the EVA, Tracy, Doug, Fyodor & Shannon completed initial post-EVA activities in the A/L, including:
• Doffing backpacks, harnesses, tethers and EMUs.
• Inspecting & taking photography of the EMU gloves.
• Taking some photos of broken threads on the MLI (Multi-Layer Insulation) of the SCU (Service & Cooling Umbilical) connector of Tracy's EMU.
• Deconfiguring the A/L after the EVA.
• Reconfiguring STTS communications in the RS.
• Downlinking spacewalk camera imagery.
• Downlinking the glove photographs for analysis.
• Restowing the NH3 (ammonia) masks & NH3 decontamination kit in the FGB.

 

[Orbinaut Pete]

Here's 3 of the best PM R&R EVA-2 images from Doug Wheelock via Twitter.

This image is just fantastic! :thumbup:

Exiting the airlock on EVA-2 in the daylight. The colors of the Earth just explode at you as you exit toward the planet. Notice what looks like scorch marks on the hatch thermal cover, the effect of vacuum and atomic oxygen on the threads and thread sealant used on the thermal cover. The 'smell' of space follows suit, I've heard it described like burnt cake or cookies, or like the smell of an extinguished match.

We used the robotic arm extensively on EVA-2, with Shannon at the controls. I am so grateful for her precision flying the arm. This photo demonstrates the delirious darkness of deep space and the sterile colorless structure of the Space Station, white and black and metallic…but when you turn toward our Earth, it is an absolute explosion of color, motion and life, a very sharp contrast that takes your breath away.

Space 'walking'?...Maybe not, but riding on the end of the robotic arm is a real perk of the job. A very unique opportunity and when you get a chance to move away from the structure of the Space Station, the view is profound and life-changing.

More images can be found at Doug Wheelock's TwitPic page.

 

[Orbinaut Pete]

NASA TV Video: "Third Time's the Charm for Spacewalkers".​

 

[docabn]

I have a technical question?

but first Woo Hooo :woohoo: and congradulations to the successful EVA!!!

Why is this pump on the outside of the station?
I'm sure there is a good reason for this, but if it were inside the EVA would have been unnessisary. And our heroes would not have gained valuble EVA experience, however, I know that they try to maximize occupany space for the crew and but leave the most critical system where the crew can get at them. I assume that this was eigther considered to be not so critical or not so likely to fail?
If anyone knows the technical answer to this pls let me know. TY

 

[Orbinaut Pete]

I have a technical question?

but first Woo Hooo :woohoo: and congradulations to the successful EVA!!!

Why is this pump on the outside of the station?
I'm sure there is a good reason for this, but if it were inside the EVA would have been unnessisary. And our heroes would not have gained valuble EVA experience, however, I know that they try to maximize occupany space for the crew and but leave the most critical system where the crew can get at them. I assume that this was eigther considered to be not so critical or not so likely to fail?
If anyone knows the technical answer to this pls let me know. TY

1. The Pump Module is too big to fit inside the station.
2. All ammonia components are located on the exterior of the station, so that if an ammonia leak occurs, the station's interior won't fill with toxic coolant (a lesson learned the hard way from Mir).

 

[DaveS]

I have a technical question?

but first Woo Hooo :woohoo: and congradulations to the successful EVA!!!

Why is this pump on the outside of the station?
I'm sure there is a good reason for this, but if it were inside the EVA would have been unnessisary. And our heroes would not have gained valuble EVA experience, however, I know that they try to maximize occupany space for the crew and but leave the most critical system where the crew can get at them. I assume that this was eigther considered to be not so critical or not so likely to fail?
If anyone knows the technical answer to this pls let me know. TY

The External Active Thermal Control System(EATCS) on the ISS use 99% pure ammonia(NH3) which is very toxic. In fact it's so toxic that the NH3 never comes in contact with the pressurized modules. Instead the heat rejection from the modules is done by a Moderate Temperature Loop(MTL) and Low Temperature Loop(LTL) which uses water.

The water passes on its heat to the NH3 at a Interface Heat Exchanger(IFHX) where the water returns to the modules and the heated NH3 goes to the S1/P1 trusses and their three large Heat Rejection Subsystem(HRS) radiators.

 

[orb]

Why is this pump on the outside of the station?

Because it's [ame=http://en.wikipedia.org/wiki/Ammonia]ammonia[/ame] coolant pump.

The U. S. Occupational Safety and Health Administration (OSHA) has set a 15-minute exposure limit for gaseous ammonia of 35 ppm by volume in the environmental air and an 8-hour exposure limit of 25 ppm by volume.

They would need to leave the station, or cut the module off, if ammonia leaked inside.

 

[docabn]

TY,
I had not thought of the consequences of an amonia coolant leak.

 

[orb]

NASASpaceFlight.com: ISS cooling configuration returning to normal confirming ETCS PM success:

After three epic EVAs, International Space Station (ISS) managers are celebrating their orbital outpost’s staged return to a nominal condition, as the replacement Pump Module on the External Thermal Control System (ETCS) Loop A provides the required cooling to the numerous systems that were forced to shut down after the July 31 failure.
...

---------- Post added 20th Aug 2010 at 00:34 ---------- Previous post was 19th Aug 2010 at 10:34 ----------

Spaceflight Now: Station crew recaps repairs as coolant system restarts.