Skip to content

RT-5: Maintainability and Reuse

Summary. "When practical, design systems for maintainability, reuse, and/or recycling to support the long-term sustainability of operations and increase Earth independence" (ADD Rev C, p. 83). ADD Rev C says "almost every element" already has some reuse, and that mass delivery and crew time drive the need. It calls robotic or automated maintenance "an architecture gap that needs additional development". Its forward look lists study topics, from common equipment to disposal of decommissioned hardware, and design features such as common batteries, filters and contact points. One of the nine recurring tenets.

All page numbers below are ADD Rev C, Section 3.5.5 (pp. 93–95).

The assessment

  • "The Moon to Mars Architecture must incorporate system maintainability, reuse, and/or recycling using common equipment in support of long-term operations and Earth independence. Almost every element in the architecture incorporates some level of reuse, but understanding the risks associated with maintainability and reuse and their impact on safety, science, and long-term sustainability goals will be vital as the architecture matures" (p. 93).
  • Safety, too. Maintenance can "further enhance crew safety by enabling the repair of systems that would otherwise put the crew in a survival situation or lead to a catastrophic hazard", more so with "the ability to reuse components from one element to meet the needs in another element" (p. 93).
  • Definition. "According to NASA-STD-8729.1, maintainability is a measure of the ease with which a system or equipment can be restored to operational status … It is important to note that maintainability does not equate to maintenance. Maintainability is a design attribute, and maintenance is a set or type of operational work" (p. 93).
  • Two drivers and three concepts. "Two main areas drive maintainability and reuse: mass delivery and available crew time." Crew time "drives three maintenance concepts: 1) reducing/limiting maintenance activities, 2) ensuring that maintenance activities are easy to perform, and 3) automating or having robotics perform maintenance tasks where possible. The last item represents an architecture gap that needs additional development" (p. 93; bold added).
  • Common equipment. The architecture "will promote the use of common equipment for components that require regular replacement (e.g., air filters)", which reduces logistics and increases contingency options. "An EVA compatibility standard ensures common components and worksites are compatible with spacesuits and do not present hazards to crew members" (pp. 93–94).
  • Gaps between missions. Because major systems "are designed to operate for multiple years and missions, extended gaps between missions drive systems to react (e.g., providing a status notification, reconfiguring systems, and shutting down specific systems) and may drive self-maintenance operations. Increasing the number of critical maintenance activities that can be automatically or remotely performed increases crew time for utilization" (p. 94).

Future considerations

  • "Maintainability remains a major concern, especially with the desire to maximize crew time for utilization activities" (p. 94).
  • Reuse matures over time. "Initial vehicles and components may have design issues learned during actual missions that need to be corrected. Systems development should plan for realistic evolution of reusability in implementation; early flights might not be assessed as qualified for reuse" (p. 94).
  • Design for repair. Designers "should consider reliability early in the design process to reduce future maintenance needs and target practical repair times", with "human factors, easy accessibility, standardized replacement methods, and limited specialized tool requirements". The lunar environment and crew-time pressure "all drive need to reduce mean time to repair" (p. 94).
  • End of life. "Architects and designers must also consider uses for decommissioned hardware and develop a strategy for the reuse or repurposing or, where reuse or repurposing are not viable, proper disposal of components" (p. 94).

Topics "that require further study" (p. 94):

  • "Incorporation of robotic systems and autonomous capabilities to perform maintenance on lunar surface systems"
  • "Incorporation of common equipment between elements"
  • "An integrated system to track the location and availability of maintenance items/common components across the Moon to Mars Architecture"
  • "A process to dispose of or reuse systems or selected system components upon completion of their primary mission"
  • "Whether and how to apply a modular open systems approach to enable a long-term autonomous repair capability supporting the Sustained Lunar Evolution segment"
  • "Evaluation of in-flight maintenance strategies and associated risks as a part of the hazard and crew survival analyses"

Design aspects to consider (pp. 94–95):

  • "Employ system designs for the lunar surface assets that consider extensibility to Mars"
  • items that notify "the broader system" of degraded capability or failure
  • "Design of systems/components to be both crew and robotically manipulated so that tasks can be performed with or without crew present"
  • "Reduction of the logistics through the use of common limited-life items (e.g., filters, lights)"
  • "Use of common equipment, including battery sizes, enclosures, and contact points"
  • "Refurbishment in support of element reuse (these activities are not well defined in the current architecture)"
  • "Recycling of material from components and use of the recovered material to create new replacement items"
  • "Overall system lifetime limitations and their effects on reuse and maintenance"

Technology gaps on the same subjects. The ADD doesn't name a gap here; the pairing is the wiki's:

Recurring tenets · RT-4 Crew Time · RT-7 Interoperability (common equipment) · Sustained Lunar Evolution · Infrastructure Support

Sources

ADD Rev C, pp. 83, 93–95