## 4 Discussion
### Mass
[44] discusses NASA plans to automate the process of refueling a satellite in space using advanced robotics. Similar robotic technologies may be used on an AM build created in space to automatically perform both polishing and indentation tests for materials' characterization. This process will require far less complexity than a UTT setup which would require a complex WEDM cut and a large testing fixture to perform the test. The unidirectional single axis of loading required to both prepare and test a MSS sample provides increased potential for automation and this study further represents the maturity and use case for MSS in situations where UTT is difficult or impossible. The small volumes probed by MSS also have the potential to produce property estimates that are substantially different from standard bulk tests (e.g., Sample number 4 in the present work). This is especially the case when the sample exhibits significant heterogeneity at the tested length scales. However, [PERSON] et al. [18] presented the capability of indentation techniques to perform a multiresolution characterization of a hierarchical material system by collecting indentation measurements with a wide range of indenter tip radii for examining the length scales of heterogeneity, and by obtaining a sufficiently large set of statistically meaningful measurements. This work further represents that heterogeneity in MSS test results is unavoidable but that the rapid rate and low cost of testing allows for increased data collection and a better understanding of this heterogeneity and how it affects the bulk properties of SLM Inconel 718. Currently, UTT-based protocols are often used to qualify AM builds using witness samples which are built alongside the part(s). However, the property measurements extracted from these samples are not likely to accurately reflect the properties of the AMproduced final part. [PERSON] [45] detailed the testing standards which are used to qualify metal AM parameters and materials and stated that there are unavoidable variations in thermal history between witness samples and the part being built. These variations in thermal history lead to property variations between the witness samples and the final AM product. MSS may be used to map the modulus and yield strength values across the cross-section of an AM-produced component and thereby produce a greater understanding of property variations throughout the part. The small testing volume and abundance of data collected from the MSS samples used in this study demonstrated that accurate property mapping is possible in SLM Inconel 718. Because of its simplicity, there is also the potential that MSS can be used to test an AM build in situ, which may then be used to provide valuable insights to improving the quality of a build during the AM process. MSFC-SPEC-3717 [46] is an example of current practices for qualifying an AM process, and it requires an array of tests including 15 tensile tests and metallographic evaluations. Since MSS can be performed directly on metallography samples as confirmed by this study, with the continued development and validation of MSS protocols, it is possible to dramatically reduce the number of required tensile tests.