Description of Driving Event:
Extravehicular Mobility Unit (EMU) and Orlan Suit Criterion
Lesson(s) Learned:
EVA ground rule 4.3.2.12, "No Simultaneous EMU/Orlan ISS Extravehicular Activity," is constraining and reduces flexibility.
Recommendation(s):
NASA should reexamine this ground rule and consider a criterion for selecting either an EMU or the Orlan suit for a particular EVA based on the specific requirements of the EVA or the specific crewmembers performing the EVA.
Evidence of Recurrence Control Effectiveness:
NASA concurs with the intent of ASAP recommendation. Current mission planning requires one-fault tolerance for both EVA hardware and personnel. Additionally, all EVA crewmembers (a minimum of three will be onboard the vehicle) will be trained to operate in both the U.S. EMU and Russian Orlan. Therefore, for example, a crewmember planning to perform an EVA in the EMU would have the following fault tolerance capability: 1) primary EMU; 2) backup EMU; then 3) Orlan. Fault tolerance alone precludes the need to plan for a simultaneous EMU/Orlan EVA; however, the primary rationale for not planning for this is the safety risks associated with two different suit procedures/parameters during a single EVA. Primary spacesuit monitoring responsibility will reside with the country responsible for the development of the hardware (i.e., Russians will have primary responsibility for the Orlan and Americans for the EMU).Therefore, if both the Orlan and EMU were in use during a single EVA, a shared responsibility for monitoring spacesuit performance exists. If an emergency occurs, there are increased safety risks that result from the shared responsibilities. Based on the increased safety risks and given the fault tolerance capability defined above, NASA does not believe it is prudent to plan for the option to use both the EMU and Orlan simultaneously.
Documents Related to Lesson:
N/A
Mission Directorate(s):
- Space Operations
- Exploration Systems
Additional Key Phrase(s):
- Aerospace Safety Advisory Panel
- Extra-Vehicular Activity
- Flight Equipment
- Policy & Planning
- Safety & Mission Assurance
Additional Info:
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