This is the second of 2 EVAs needed to outfit the PMA-3 to be ready for its conversion to a commercial crew docking port. See my previous post for US EVA-40 and PMA-3 Relocation.

Crew member Shane Kimbrough is EV1 (red stripes) and Peggy Whitson is EV2 (no stripes).
Main Tasks:

  • MDM removal and replacement (EXT-1 Zenith)
  • PMA-3 connections
  • PMA-3 cover removal
  • Node 3 port axial shields installation

On Thursday March 30, 2017, the 2 crew members exited the Quest Airlock to initiate US EVA-41. Shane Kimbrough headed to the S0 truss and Peggy Whitson translated towards the newly installed PMA-3.

Peggy Whitson (EV2 no stripes) is at the base of PMA-3 working with the connections of cables to PMA-3.

Another angle showing Whitson connecting cables on PMA-3.

Whitson then climbed to the top to release some straps to free up the cover. Peggy had difficulty releasing the cover because it has gotten stiff after all these years since the end of the Shuttle Program.

MLI cover almost removed.

The MLI cover has been removed from PMA-3.

Shane Kimbrough (EV1 red stripes) started the EVA like his previous spacewalk heading to the S0 truss to replace a second of two External Control Zone Multiplexers/Demultiplexers with a new, upgraded unit. After the EXT-2 MDM was changed out on EVA-40, the focus on Thursday was on the EXT-1 unit mounted to the zenith side of the central truss segment.

Kimbrough is at the S0 truss to work on the second MDM.

Zenith MDM

Kimbrough is in position to work on the zenith side of S0 to access the old MDM.

After Kimbrough was able to replace the old MDM unit, he then headed to assist Whitson to stow away the MLI cover from PMA-3.

Both astronauts folding the cover into its bag (not seen in this demonstration).

Then both astronauts headed back to the Airlock to retrieve the axial shields for Node 3 port side.

Both astronauts seen at the port side of Node 3 to install the axial shields.

During the setup, the astronauts ran into a snag with one of the 4 shields that became untethered and floated away from Shane kimbrough. The shield was lost.

Despite the setback of losing a piece of hardware, the spacewalkers continued in methodical fashion while efforts at Mission Control became slightly more frantic as controllers began thinking on their feet to come up with a provisional plan to fully cover the berthing port. Engineers convened in a back room at Mission Control and worked with a replica of the PMA-3 cover to see whether it could be turned into a shield for Node 3.

By the time the crew completed the axial shield installation, teams on the ground had come up with a workaround to get the exposed quad protected by using the PMA-3 cover that had been removed earlier in the EVA. Teams modeled possible attachment points of the cover on the Node 3 endcone and concluded it would be possible to secure the cover in place to provide adequate thermal and MMOD protection to the CBM.

Axial Shields part to be attached to Node 3 Port Side. DO NOT GLUE IN PLACE.

The astronauts headed back to airlock to remove the stowed MLI cover and use it to protect the exposed quad. Ground controllers guided the astronauts how to tie the cover to the shields, thus preserving it for future use by the NanoRacks Commercial Airlock headed to ISS toward the end of the current decade.

Actual configuration of Node 3 Port Side with the axial shields and MLI cover.

The US EVA-41 ended at 7 hours and 4 minutes accomplishing all of the EVA’s objective tasks.

Download File:
AXMEVA41 Node 3 Port Side Axial Shields (1:100 scale)



2 responses to “US EVA-41

  1. Wow, that was quick. Thanks for whipping up the alternative cover and photo essay so quickly. I can’t imagine how much ribbing the EVA team must be getting for letting the cover slip away. How about that SpaceX news, eh?

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