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National Aeronautics and Space Administration

EVA23Water Intrusion

3.0 Data and Analysis 3.1 Approach The MIB investigation approach was challenged by the circumstances of the close call event. The EVA took place onboard ISS which is an operational facility on orbit. The ISS has multiple failure scenarios that can lead to it becoming zero-fault tolerant to the loss of the ISS vehicle. If any of these failures occur, the ISS is at great risk for a total loss of vehicle event until the failed component is replaced. Most of these failures require an EVA to remedy. Therefore, it is possible that an EVA could be required to save the ISS at any time, even prior to the determination of the root cause of the EMU water close call. [Note: at the time of submission of this report, prior to root cause determination, a series of EVAs required to safe the ISS was underway]. This possibility required the ISS Program to quickly establish the ISS Investigation Team which was tasked with determining the root cause of the failure as well as determining what safety measures would need to be in place in the event an emergency EVA was required. Because this team was in place at the time the MIB was convened, the MIB was directed to work very closely with the ISS Investigation Team. To facilitate this, the MIB established a positive working relationship with the ISS Investigation Team and attended team meetings as well as participated in testing. In addition, the MIB obtained the services of a consultant with many years of experience as a former subsystem manager for the EMU to consult both for the MIB as well as the ISS Team. His participation allowed for easy knowledge transfer among all of the teams. The MIB was responsible for ensuring that further EVA close calls were avoided, therefore, the MIB was involved in all decisions related to preparations for a potential emergency EVA. An additional challenge for the MIB was the fact that the failed hardware was on orbit so access to it was difficult. Hence, much of the data gathered and used by the MIB to develop findings was gathered during privileged interviews conducted with individuals from a broad spectrum of organizations that were involved with EVA operations. This included individuals who were directly involved in the events of EVA 23 as well as managers, engineering specialists, and contractors who support the Agency’s efforts to perform EVAs. There were also many less formal discussions that took place with both individuals and groups that helped the MIB better understand organizations and their inter-relationships to look for areas that worked well and areas that had weaknesses. The MIB also collected and reviewed many historical documents to determine the information available to the EVA teams prior to and during the events being investigated. The MIB also participated in many meetings held by the ISS Program related to investigating the hardware failure and developing methods to protect future EVA crew members. In addition, the MIB evaluated telemetry data from the EMUs themselves to better understand the nominal performance of the suits as well as off nominal behavior due to water intrusion.

3.2 Type of Data Gathered: List of Documents Data gathered during the Mishap Investigation includes video and audio feeds, transcripts of communications between MCC and ISS (during EVA 23, EVA 22 debrief), audio voice loop communications within MCC, witness statements, console logs, previous reports and investigations, drawings, photographs, technical materials, and meeting minutes — from a multitude of sources. For the complete list of documents and data gathered, refer to Appendix B: List of Documents.


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...