Saturday Spacewalk Kicks Off Addition of Commercial Crew Docking Ports to ISS


Spacewalking NASA astronauts Barry "Butch" Wilmore and Terry Virts initiated the installation of the first of two planned International Space Station docking ports for future U.S. commercial crew transportation vehicles on Saturday by extending external power, data and thermal control cabling along the orbiting science lab's Harmony and Destiny laboratory modules.

The near seven hour excursion unfolded without difficulties from either of the fan pump separators in the two space suits, a safety concern that emerged in December and January and persisted up to the start of Saturday's spacewalk. Virts experienced a slight buildup of carbon dioxide in his suit from all of the exertion.

NASA's Barry "Butch" Wilmore, left, and Terry Virts install power, data and heater cables near future ISS docking port for commercial crew vehicles. NASA photo

The two men started 30 minutes late but surged ahead of schedule, accomplishing some of the work assigned to the second in a series of three excursions over the next nine days.

The fan pump separators are part of the space suit life support system that circulates air and cooling water. The devices originally assigned to Saturday’s excursion failed to spin up during late 2014/early 2015 checkouts inside the station's airlock.

The steady performance of the fan pump separators on Saturday was a welcome development.

NASA plans a second and third spacewalk by the two men on Wednesday and Mar. 1 to complete the power, data and thermal control cable task. They also intend two antenna installations and communications cable extensions before Wilmore's scheduled return to Earth. He departs late Mar. 11 with two Russian cosmonauts to conclude 167 days aboard the orbiting science lab.

The primary work site for Saturday's outing was the 16-year-old Pressurized Mating Adapter-2 on the forward end of Harmony, which served as the docking port for NASA's space shuttle fleet until the winged orbiters were retired in mid-2011. Wilmore, the station's current commander, and Virts made five power, data and thermal control connections under two orbital debris shields on either side of PMA-2 and three additional cable connections, including two linkups that were originally scheduled for the second spacewalk.

"I worked up a lather on that one," quipped Wilmore as he marched through the first set of PMA-2 cable connections.

"You guys have done just a superb job,” Mission Control told the two men as they entered the home stretch of Saturday’s activities.

In all, Wilmore and Virts are to install 10 cables totaling 364 feet over the first two spacewalks to prepare PMA-2 for outfitting with the first of new NASA and Boeing developed International Docking Adapters. The IDAs will serve as the actual mechanical links between the station and future commercial crew vehicles operated by Boeing and SpaceX under NASA contracts.

As Saturday’s spacewalk drew to a close at 2:26 p.m., EST.

NASA's goal is to achieve the first commercial crew vehicle docking with astronauts by the end of 2017.

SpaceX is to deliver the first of the IDAs aboard the company's seventh commercial re-supply mission in June. The initial IDA would be installed on PMA-2 during a NASA spacewalk currently planned for July.

This year, NASA also plans to move the identical PMA-3 from the station's Tranquility module to the space facing circumference of Harmony. A second IDA is manifested for delivery aboard another SpaceX resupply mission planned for late this year.

During Wednesday's spacewalk, Wilmore and Virts are to complete the PMA-2 cabling and lubricate the grappling mechanism on the station's Canadian-furnished robot arm. The 58-foot-long mechanical limb will be used to relocate PMA-3 as well as move the station's Leonardo Permanent Multipurpose Module from the Earth facing side of the station's Unity module to the forward end of Tranquility. That move will ensure sufficient clearances for a pair of commercial cargo berthing ports as well as the two commercial crew parking spots.

During the March 1 spacewalk, Wilmore and Virts are to install two communications antennas and string another 400 feet of cabling along the station's port and starboard solar power trusses to support the transmission of navigational data for automated commercial crew rendezvous and dockings.

The source of the balky space suit fan pump separator issue that surfaced in December and January  was traced to a corrosion buildup on internal bearings. The corrosion was blamed on water intrusion. Those initial suspicions were confirmed after the two fan pump separators that failed to activate were removed from the space suits and returned to Earth earlier this month aboard the fifth SpaceX Dragon resupply mission. The devices were turned over to United Technologies Corp., the space suit contractor, for evaluation.

The fan pump separators have been activated between spacewalks at an accelerated pace during check outs of cooling system water quality, which has increased the opportunity for exposure of the bearings to water, according to NASA.

The unwanted presence of silica particles in the cooling water was blamed for a July 2013 incident in which water flowed into the space suit helmet worn by European Space Agency astronaut Luca Parmitano. Parmitano retreated to the airlock as water invaded an airflow vent, massing around his eyes, nose and ears. Engineers found small water ports in the pump blocked by silica particles that migrated from water filters. The blockage diverted cooling water into the helmet air flow vent.

The U. S. chaired ISS mission management team cleared Saturday's spacewalk on Thursday after determining any corrosion in the fan pump separators in suits worn by Wilmore and Virts was minimal.

However, NASA's Mission Control refined the governing rules for the excursion by stipulating that work would be halted without further troubleshooting if there were signs of problems with the air and water circulation devices.

In the meantime, NASA has also changed its space suit cooling water quality checkouts to include additional air flow over the bearings as a dry out measure.

Discuss this Blog Entry 6

on Feb 22, 2015

We have certainly come a long way from the Gemini mission in which the astronaut had to return to the cabin because he was overheated, exhausted, disoriented, and had fogged his visor to the extent that he almost could not see. Many of us were concerned at this time we could only float around passively in space, but any work or exertion might prove to be very difficult. It was just a bad data point probably due to insufficient hand holds and so on, but was a very bad sign for productive EVAs needed for Apollo or for ever constructing anything like a space station. We were worried about nothing. We just needed to reherse in neutral buoyancy tanks and practice, practice, practice.
Space suits had to be improved too.

on Feb 22, 2015

I should have mentioned that this bad experience during an EVA happened during Gemini 9 to Gene Cernan after only a two hour long EVA. Now the ISS astronauts & Cosmonauts make it look almost too easy.

Actually, NASA has a historic web site where I will search for more details on why Gene got so overheated he had to return to the cabin of Gemini. This occurred in June of 1966, when Gemini was being launched very frequently into LEO, like every few monhs. Wiki is also a good source if you are interested.

on Feb 23, 2015

We have indeed come a distance from the dreams of the 1950's and early 60's. While we do not have a 'Cosmic Construction Corps' we have astronauts making hours long working space walks look routine.

The visioned space stations, built like wheels and powered by tame nuclear energy, have yet to arrive. Rather our ISS is built like a growing branch, sprouting buds (docking ports and new modules) and leaves (solar panels). In our reaching for the moon and planets we are borrowing from God's engineers.

One company is gathering volunteers for a permeant colony on Mars. Very optimistic. I would have gone for the moon. It will be our industrial base for the exploration of the solar system. It will also be where we look at power systems and all the baggage we need to expand. The moon will see children before Mars. Better include a doctor and a cleric in that colony, along with some teachers. Dream big.

on Feb 25, 2015

Slow incremental progress in spite of the current administration's misdirection and neglect. We should already be on the moon permanently by now. I agree with Peter, Moon first, Mars second.

on Mar 10, 2015

nice information

on Mar 18, 2015

I saw part of an interview on NASA TV with Alexei Leonov this week (it's the 50th anniversary of the first EVA). He gave some additional new info. Apparently he was supposed to re-enter the airlock by reeling himself in by the tether, which had hooks every meter or so that were supposed to be hooked to his suit as he approached the airlock (a generous term for what served as such on Voshkhod 2). His suit had been tested in a vacuum chamber to 40km but no facility on earth could test it to 400km, so he knew there was going to be some unknown and he was trained to depressurize the suit. As he began the re-entry procedure his gloves were apparently becoming unusable and he couldn't hook the tether but was somehow able to reel himself in, depressurizing his suit from 1 atmosphere to .27 atmospheres (ouch).

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