Additive Manufacturing (“AM”), or 3-D printing, has been primed to disrupt the manufacturing design, prototyping, production and supply chain processes for over 3 decades, but only recently have years of advances begun to find consistent economical applications . For NASA, an organization on the forefront of exploration, the opportunities that AM presents from a design and prototyping standpoint are both ripe and widespread.
First, AM enables structural innovation and the creation of manufactured pieces that simply cannot be produced through traditional subtractive methods (complex geometries and captivity-based geometries) . Second, AM enables the facilitation of wide-ranging, rapid and economical experimentation. It empowers researchers to be nimble in the creation and subsequent testing of prototypes with a range of materials, composites, infills, shapes / sizes, and weight efficiencies  . AM enables experimentation to be cost-efficient and time-efficient without the need for third parties and helps tackle the need for innovative, flexible, unconstrained, custom solutions to meet NASA-specific needs and quality requirements   . In short, AM has created the opportunity to enhance the product development and product improvement processes at NASA.
The advancement of AM’s application, quality, costs and speed is ever-changing, and, to date, NASA has been on the forefront of applying AM  . Successful test announcements from NASA include the successful testing of a rocket engine injector in 2013, the creation of a full-scale copper rocket engine part in 2015, and the production of a copper combustion chamber liner in 2018. In each of these developments, NASA reduced costs materially (up to 70%) and often cut timelines from weeks to days, with additional cost and time-efficiencies on the horizon   . Each of these successive prototyping projects built on each other and created unique solutions to challenging problems. These announcements also point to further AM applications at NASA, with the organization noting, it’s now “ready to move on to demonstrate the feasibility of developing full-size, additively manufactured parts” .
Given the innovative promises associated with AM, NASA should lean into the use of AM for prototyping purposes; however, it should be extremely cautious when exploring AM capabilities beyond experimentation applications. The cause for caution is amplified when thinking about the “failure is not an option” mantra at NASA and the “unknown unknowns” associated with any nascent technology (no long-term track record) .
NASA needs to be keenly aware of the AM’s many challenges. First, quality control and testability are particularly challenging and there are no well-defined standards . AM is a new technology: there is limited knowledge of potential weaknesses, it is unclear whether conventional tests are appropriate for integrity verification, and there are many unknown unknowns about AM in the extreme environments of space  . Second, there is significant endurance ambiguity, with the absence of data to understand performance. Third, variability between CAD designs and AM outputs (as well as between different build iterations), needs to be carefully monitored, measured and tested   . Lastly, to date, most AM components have been designated for nonstructural and noncritical use cases, which limits the incremental data available for integrated components into mission critical structures and should give NASA pause about the developmental stage of the technology .
Looking ahead, NASA should continue to explore the use of AM, particularly in no-stakes, small-scale prototyping phases; however, like its highly incremental approach to exploring the use of AM in space, it should remain cautious and take an incremental approach to considering AM components for mission-related applications . In this pursuit, NASA should be focused on i) working with the International Standards Organization (ISO) to continue to develop standards for AM ; ii) sharing industry best practices with corporations to advance AM methodologies; iii) not becoming overly reliant on AM for the production of mission-critical components due to NASA’s own acknowledgement that “gaps exist in the basic understanding of AM Materials and Processes, creating potential for risk to certification of critical AM Hardware” .
As seen in 1986 Space Shuttle Challenger disaster and the failure of O-ring seals, one, seemingly insignificant, component can create systemic weaknesses and result in catastrophe . Initial AM research on-earth suggests that critical defects are rare from selected AM samples, but there is little to no data to support measurement, integrity and endurance of AM in space . From all of this, two questions standout for NASA looking forward: 1) what thresholds must be met before NASA uses AM for critical, load-bearing, structural components? 2) should NASA focus resources on the development of “in-space” AM on the International Space Station for non-critical components or are such efforts simply distracting?
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