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National Aeronautics and Space Administration


EVA23Water Intrusion

EVA 23 Translation to the Airlock Event

EV2 first called the ground to report water accumulating in his helmet PET 44 minutes into EVA 23. In the following 10 minutes, the ground team tried to get additional information from EV1 and EV2 in order to try to ascertain the source of the water leak. On the Space to Ground loop, EV1 reported seeing too much water in EV2’s helmet, and EV2 reported that the water was increasing. After 5 to 10 minutes of discussion, the ground team decided to terminate, making the call 23 minutes after EV1 first reported the water. They instructed EV2 to return to the Airlock and for EV1 to secure the hardware outside and return to the Airlock. It took about 5 minutes for EV2 to translate back to the Airlock. During that time, EV2 expressed disappointment with having to end the EVA too soon. From the interviews, it is clear that EV2 tried to communicate during his translation to the Airlock; the ground team inquired about EV2’s status while translating, but received no response until EV2 reached the Airlock. During post-mission interviews, it was discovered that EV2 had experienced loss of comm issues during this timeframe. EV1 arrived at the airlock 2 minutes later, closed the hatch, and began repress. As repress commenced, it became clear that EV2 was unable to hear or speak well, so at one point the crewmembers communicated by squeezing each other’s hands. The ground team reviewed the repress procedures and opted to expedite the process, based on their concerns for EV2’s safety with the increasing water. After the repress was completed, IV helped EV2 and then EV1 doff their suits. When they removed EV2’s helmet, they noticed that his head and face were lined with a thin film of water: the water was over his eyes and near his nose and mouth. His comm cap was completely saturated with water, and it had filled his ears. There was also a large of amount of water pooling near the back of his helmet, around the T2 vent port. During the post EVA 23 debrief a few hours later, EV2 reported losing visibility as soon as he started translating to the Airlock following the call to terminate. He recalled using the safety tether as a guide to get back to the Airlock. EV2 also confirmed that he had comm issues that began early on during his translation to the Airlock; initially he had been able to hear the ground and EV1, but wasn’t receiving responses. Once he was inside the Airlock, he wasn’t able to hear even those communications. This information surprised the ground team. During interviews, team members expressed surprise about the amount of water in EV2’s helmet and how it impacted his ability to see, communicate, and breathe. EV1 indicated in a post-flight interview with the MIB that he had a strong sense that EV2 was having difficulty navigating to the Airlock and he wished he had been there to help him. While the team was concerned about crew safety, specific concerns regarding EV2’s ability to get back to the Airlock on his own were not discussed, most likely because neither EV1 nor the ground team was aware of the severity of the situation. This information was not communicated real-time, possibly because EV2’s comm cap was not working properly. The following human factors issues were considered during EV2’s translation to the Airlock, and will be discussed in detail in the following section: conditions that limited EV2’s visibility; communication equipment issues that prevented effective communication between EV2, the ground team, and EV1; personality styles that may have impeded communications; inadequate risk assessment; and training issues that may have contributed to the lack of knowledge that made it difficult for both teams to share and request information that would have helped them understand the severity of the situation or evaluate the risks that EV2 could become incapacitated because of the situation. It’s important to emphasize the fact that the ground team ultimately made the right decision to terminate the EVA when they did. EV2 was able to return to the Airlock with enough time to complete the expedited repress. If the ground team had taken additional time during EVA 23 to diagnose the source of EV2’s water, the outcome might have been catastrophic. While the decision to not spend more time diagnosing the source of the water leak during EVA 23 prevented a catastrophic situation, in retrospect it becomes apparent (as explained in Appendix A.1) if a more thorough diagnosis of the leak that occurred during EVA 22 might have prevented this life-threatening situation. The following human factors analysis


ISS EVA Suit Water Intrusion Mishap Investigation Report  

Report of the NASA Mishap Investigation Board examining the high visibility close call event of July 16, 2013 when ESA astronaut Luca Parmit...