Expedition 36 Flight Engineers Fyodor Yurchikhin and Alexander Misurkin have completed their second spacewalk in the space of a week, as preparations continue for the arrival of the next Russian module. Meanwhile, Luca Parmitano has recalled the drama of his aborted spacewalk when liquid started to fill his helmet during EVA-23 last month.
Thursday’s spacewalk was a follow-on to the record-breaking EVA-34/RS-34, which was supposed to only last six and a half hours.
As last week’s EVA extended past the seven hour 16 minute mark, it beat the previous record duration EVA for the Russians, namely the 1990 EVA on the Mir space station that repaired insulation blankets that were flapping loose on the Soyuz TM-9 reentry vehicle.
EVA-34 closed out on the seven hour, 29 minute mark, to set the new Russian record. However, it was still shy of the world record, which was registered during STS-102 in March of 2001, when Jim Voss and Susan Helms conducted an eight hour 56 minute spacewalk, as much as two and a half hours of that EVA was conducted from inside Discovery’s airlock.
“All EVA objectives were completed including routing of MLM power and ethernet cables, installation of the Vinoslivost experiment panel, and installation of two gap spanners,” noted ISS status information. “The crew also completed a get ahead task to retract the Strela.”
Thursday’s EVA didn’t come close to challenging the record, with the focus on replacing a laser communications experiment with a new optical camera system, the move of a foot restraint, and also inspection a number of sites for what caused an antenna cover to come loose.
EVA controllers in Moscow initially decided to remove a task related to the installation of an EVA work station, and the associated foot restraint relocation, after the spacewalkers noted the configuration was out of family.
However, much to the surprise of everyone, including NASA, the spacewalkers then decided to install it, even with its misalignment, given the problem is only observed when the hardware is in the yaw position, which can be mechanically corrected.
The cover that came loose was spotted out of the ISS’ windows by Expedition crew members, was videoed the cover floating outside of the Station.
“Service Module (SM) Antenna Cover: The crew reported that they saw an item floating aft of the International Space Station (ISS). The object was later identified to be a SM antenna cover,” noted ISS status information.
“There are several similar covers on the SM and the team is working to identify which one was lost. Based upon the crew’s relative motion estimate, the antenna cover is not considered to be a recontact threat.”
The spacewalkers tightened the screws on the other WAL antennas during the EVA.
Thursday’s spacewalk began at 11:34 UTC, as the duo departed from the Pirs airlock. It concluded – after a lot of Russian flag waving on what is Flag Day in Russia – at 17:32 UTC, concluding a five hours, 58 minute EVA.
The spacewalk was the 173rd in support of space station assembly and maintenance, the eighth of Yurchikhin’s career and the third for Misurkin.
Yurchikhin was set to wear a Russian Orlan suit bearing red stripes, while Misurkin donned suit (#6) with blue stripes. However, both cosmonauts were wearing suits with blue stripes after Yurchikhin swapped the suit (#5) he used during EVA-34, for suit #4.
Both of the suits were equipped with a US helmet camera to provide close up views of the work they are performing outside the station.
While the Russian EVA is utilizing the Orlan suits, the US EMUs remain “grounded”, following the aborted EVA-23 last month.
Investigations into the failure of Luca’s suit are continuing, with the latest theory revolving around a vent loop water leak, caused by either a blocked or clogged Water Separator Pilot Tube, a blocked condensate water relief valve, or a blocked condensate water line – causing the water separator loop to allow excessive amounts of water to enter the ventilation loop.
NASA’s Anomaly Resolution Team (ART) are at the center of the investigation, working closely with the ISS team who are making preparations to send up various elements of hardware on upcoming Russian and commercial vehicles.
However, it was Luca’s own words, via a blog post, that provided the personal observations of what it was like during the termination of the EVA, as water started to enter the Italian’s helmet.
“I ‘feel’ that something is wrong,” noted the ESA astronaut, as he was just about one hour into his EVA tasks. “The unexpected sensation of water at the back of my neck surprises me – and I’m in a place where I’d rather not be surprised.
“I move my head from side to side, confirming my first impression, and with superhuman effort I force myself to inform Houston of what I can feel, knowing that it could signal the end of this EVA.”
After informing the ground (Mission Control Center Houston, ISS Flight Control Room), Luca was joined by his EVA partner, Chris Cassidy, who helps to make visual observations of the water collecting in Luca’s helmet.
“At first, we’re both convinced that it must be drinking water from my flask that has leaked out through the straw, or else it’s sweat. But I think the liquid is too cold to be sweat, and more importantly, I can feel it increasing,” Parmitano wrote.
“I can’t see any liquid coming out of the drinking water valve either. When I inform Chris and Shane (Kimbrough – in MCC-H) of this, we immediately receive the order to ‘terminate’ the sortie. The other possibility, to ‘abort’, is used for more serious problems. I’m instructed to go back to the airlock.”
With the MCC-H controllers switched into their contingency plans, planning they continually train for, Luca began to head back to the Quest Airlock – a task made far more difficult as water started to increase inside his helmet.
“As I move back along my route towards the airlock, I become more and more certain that the water is increasing. I feel it covering the sponge on my earphones and I wonder whether I’ll lose audio contact,” he continued to write.
“The water has also almost completely covered the front of my visor, sticking to it and obscuring my vision. I turn ‘upside-down’, two things happen: the Sun sets, and my ability to see – already compromised by the water – completely vanishes, making my eyes useless; but worse than that, the water covers my nose – a really awful sensation that I make worse by my vain attempts to move the water by shaking my head.
“By now, the upper part of the helmet is full of water and I can’t even be sure that the next time I breathe I will fill my lungs with air and not liquid. To make matters worse, I realise that I can’t even understand which direction I should head in to get back to the airlock. I can’t see more than a few centimetres in front of me, not even enough to make out the handles we use to move around the Station.”
Remembering his safety cable, Luca utilizes its small recoil to allow him to ease back towards Quest. However, the Italian started to fear time was running out, and that he needed a last resort plan – to begin a controlled depress of his suit to freeze the collecting water.
“I start to move, all the while thinking about how to eliminate the water if it were to reach my mouth. The only idea I can think of is to open the safety valve by my left ear: if I create controlled depressurisation, I should manage to let out some of the water, at least until it freezes through sublimation, which would stop the flow. But making a ‘hole’ in my spacesuit really would be a last resort.”
Luca – now joined by Cassidy – finally make it back to Quest, although by this point Parmitano is all-but blind from the water that had collected around his face.
“I move for what seems like an eternity (but I know it’s just a few minutes). Finally, with a huge sense of relief, I peer through the curtain of water before my eyes and make out the thermal cover of the airlock,” he added. “Just a little further, and I’ll be safe.
“Moving with my eyes closed, I manage to get inside and position myself to wait for Chris’ return. I sense movement behind me; Chris enters the airlock and judging from the vibrations, I know that he’s closing the hatch.”
Although now inside the relative safety of Quest, Luca knew he still required a back-up plan if the water situation became unbearable, even if it would have resulted in a very undesirable scenario for himself.
“I try to move as little as possible to avoid moving the water inside my helmet. I keep giving information on my health, saying that I’m ok and that repressurization can continue.
“Now that we are repressurizing, I know that if the water does overwhelm me I can always open the helmet. I’ll probably lose consciousness, but in any case that would be better than drowning inside the helmet.
“At one point, Chris squeezes my glove with his and I give him the universal ‘ok’ sign with mine. The last time he heard me speak was before entering the airlock!”
Finally, the Quest Airlock is repressurized and Luca is pulled into the ISS where his helmet was carefully removed.
“The minutes of repressurization crawl by and finally, with an unexpected wave of relief, I see the internal door open and the whole team assembled there ready to help. They pull me out and as quickly as possible, Karen unfastens my helmet and carefully lifts it over my head.”
Thanks to the professionalism of the ISS crew and the teams on the ground in Houston, Luca’s safe return provided yet another example of the world-class training the teams are put through day-in, day out.
“Space is a harsh, inhospitable frontier and we are explorers, not colonisers,” added Luca in summary to his experience. “The skills of our engineers and the technology surrounding us make things appear simple when they are not, and perhaps we forget this sometimes. Better not to forget.”
(Images: L2’s ISS Section and NASA)
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