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The Development Of An ISRU Activity Site Selection Tool Dale S. Boucher*, Leanne Sigurdson

Northern Centre for Advanced Technology Inc (NORCAT), Sudbury, Ontario, CANADA, P3A 4R7

I. Abstract In Situ resource Utilization (ISRU), by definition, involves developing an understanding of resources available

for use by mission planners in support of human or robotic activities. ISRU that proposes to use surface or sub surface materials and resources MUST utilize a delineation program to ensure viability of the processing of these resources into useable materials. The delineation of subsurface resources can ONLY be achieved with a credible drilling and sampling program.

Any mission utilizing subsurface resources must use such a process to delineate the resource and profile its quality as a pre-cursor to development of a credible processing capability. One of the critical points to consider when attempting to establish a mining activity, is that nature is non-homogeneous. That is, resources are rarely distributed homogeneously in a substrate. It is therefore necessary to delineate the resources in terms of location in 3D space; quantity in terms of resource availability vs. waste, and quality, in terms of resource availability and energy of release or refining.

Drill Site Selection is a unique Canadian capability based upon drilling which is proving to be portable to other ISRU type activities. Site Selection was developed by NORCAT to attempt to improve the likelihood of drilling a successful drill hole for the RESOLVE project. The technology is predicated upon the time and power availability for the drilling portion of the RESOLVE experiment. It is expected that no more than 20 drill holes will be drilled during the life of the RESOLVE mission. As such, the effort is to ensure the drill can penetrate to its full 1 metre depth in regolith and NOT drill through significant size rocks or into bedrock, as the time and energy requirements for this would detract from mission life. A hole drilled into bedrock is considered a blind or wasted hole, from which RESOLVE specific data could not be extracted.

This technology relies upon the detection and interpretation of surface features near a prospective drill site to predict viability of the site to produce positive drilling results. The surface features are identified from a Neptec Triangulation LIDAR (TriDAR) scan data set and reduced via a Xiphos Hybrid Processor Card (HPC) to compress the data stream. The data stream is transmitted from site to CSA HQ, via a satellite C&C link, for final approval and interpretation by a geo scientist. The objective is to allow operators sufficient insight into the quality of the surrounding terrain to make informed decisions regarding the viability of a potential activity site.

A geo-technical evaluation filter was developed and tested as an autonomous feature that will assist in the pre-selection of potential drill sites. The tool is called the EXploration Positioning, Localization and Orebody REcognition (EXPLORE) tool. The system includes a Neptec TriDAR, a Xiphos 3Di Hybrid Processing Component (HPC) and geotechnical filter constraint regulations. The output of the tool and interpretation is a bearing and distance, which would be sent to the rover Navigation team for inclusion as a destination point in the overall rover path planning activity.

II. Introduction The EXploration, Positioning, Localization and Orebody REcognition (EXPLORE) system evaluates the

physical characteristics of a potential In Situ Resource Utilization (ISRU) activity site using, as a minimum, vision system data and geotechnical criteria. Initially, the geotechnical criteria were developed to assess the “dry hole” (a drill hole that is failed or of no interest) potential of a drill site location. This was used as a mission cost mitigation strategy. However, it has become apparent that this system can be ported to numerous ISRU related activities, such as typical ISRU site selections for regolith extraction and landing pad construction. The recent work on using other data sets in addition to the vision system data and the expansion of the criteria matrices allows ISRU system planners to utilize EXPLORE for ISRU extraction type activities and begin to examine the potential for use in the definition of ISRU ore bodies, or geo-physical areas of interest.

EXPLORE’s geotechnical criteria apply geomorphologic surveying principles in a method that will be useful for designing, engineering and constructing a landing pad at a lunar outpost. A scientific understanding of landforms and their formation in an area of interest is useful in resource detection and hazard assessment. The identification of terrain formed by geological (tectonics and volcanism), erosional (wind and water) and extraplanetary (meteorite impact) processes allows inference of the general subsurface conditions within the logical boundaries of a specific

* Director, Innovation and Development, NORCAT Inc, 1545 Maley Dr, Sudbury, Ontario, CANADA, P3 A 4R7.

AIAA SPACE 2009 Conference & Exposition14 - 17 September 2009, Pasadena, California

AIAA 2009-6429

Copyright © 2009 by NORCAT Inc. Sudbury, Ontario, Canada. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.

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terrain. All these processes may be present in a planetary environment. For example, Mars is subject to the formation and erosion of rocks by Aeolian processes (wind), and both the moon and Mars have been subject to volcanic activity. EXPLORE’s geotechnical criteria have been designed as a rule base in order to infer and understand subsurface features in an area, and support speculation of specific conditions that may be encountered during an ISRU activity. Complex geology at a site could affect exploration and construction within that area and the physical characteristics of the site may provide clues to the subsurface lithology.

Originally the geotechnical criteria made use of geomorphologic principals to detect resources for ISRU drilling (Figure 1). It has been determined that the geotechnical criteria can be applied to numerous ISRU activities including landing pad construction, reactor burial, open pit mining, and access way construction. The geotechnical criteria provide an indication of the geologic processes that may have affected the site and would in turn affect the construction of an excavation site.

Many physical characteristics in a region can be identified using the TriDAR and these may provide clues to subsurface conditions. NORCAT has developed specific geotechnical criteria to methodically evaluate the physical characteristics of a scanned area. Five categories are assessed in the process: free area, structure, surface, slope and topography. The physical characteristics of the area are given a rating from 0 to 5 for each category, 0 being least suited to a drill site, 5 being most suited.

Figure 1: Drill Site Selection Geotechnical Criteria, version 1

A landing pad is a large area specifically designed to support numerous landings and launches. Minimal resources, such as fuel and air, on the moon necessitate landing pad placement within close proximity to the outpost. As such, the landing pad requires a protective barrier to shield other facilities from the effects of ascent and descent plumes. The engineering of a landing pad must take a number of factors into consideration prior to construction. These include the area the landing pad will encompass and its use and re-use as numerous landings and launches would be required over the life of an outpost. The evolution of EXPLORE’s geotechnical criteria required contemplating and evaluating the applicability of existing criteria (Fig 1) for a variety of ISRU activities. Figure 2 shows version 1 of the excavation site selection criteria.

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Figure 2: Excavation Site Selection Geotechnical Criteria, Version 1

Figure 3: Drill Site Selection Geotechnical Criteria, Version 2

Access ways are required regardless of the purpose of the excavation activity. Access way placement requires a geotechnical investigation to obtain the greatest amount of information as early as possible in the development of an access way. This would identify critical issues that could impact the specifications, design and construction of the access way from the main road to the excavation site.

The access way placement geotechnical criteria have been designed as a separate tool from the excavation site selection geotechnical criteria. There are certain factors in the design of an access way that are not necessarily applicable to the selection of an excavation site. For example, if the access way is placed over a topographical feature such as a hill or a crater, at an angle ranging from above 0° to 10° it is more likely to require extensive backfill or excavation during construction than if placed over the feature at an angle that is closer to perpendicular (45° to 90°). However, the volume of material available for backfill will factor heavily into this decision. Placement of the access way must be taken into consideration when selecting an excavation site. Therefore, it is necessary to use the access way placement criteria in conjunction with the excavation site selection criteria

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Figure 4: Access Way Placement Criteria

III. Drill Site Selection Testing Drill Site Selection is a unique Canadian capability based upon drilling which is proving to be portable to other

ISRU type activities. Site Selection was developed by NORCAT to attempt to improve the likelihood of drilling a successful drill hole for the RESOLVE project. The technology is predicated upon the time and power availability for the drilling portion of the RESOLVE experiment. It is expected that no more than 20 drill holes will be drilled during the life of the RESOLVE mission. As such, the effort is to ensure the drill can penetrate to its full 1 metre depth in regolith and NOT drill through significant size rocks or into bedrock, as the time and energy requirements for this would detract from mission life. A hole drilled into bedrock is considered a blind or wasted hole, from which RESOLVE specific data could not be extracted.

This technology relies upon the detection and interpretation of surface features near a prospective drill site to predict viability of the site to produce positive drilling results. The surface features are identified from a Neptec Triangulation LIDAR (TriDAR) scan data set and reduced via a Xiphos Hybrid Processor Card (HPC) to compress the data stream. The data stream is transmitted from site to CSA HQ, via a satellite C&C link, for final approval and interpretation by a geo scientist. The objective is to allow operators sufficient insight into the quality of the surrounding terrain to make informed decisions regarding the viability of a potential activity site.

BeTSI is the TriDAR’s Windows human machine interface (HMI) designed to acquire, access and visualize raw scan data. BeTSI communicates with the TridarRelay on the 3Di hybrid processor card (HPC) to issue control level commands to the vision system to configure the TriDAR and initiate scans. Figure 5 depicts a time of flight (TOF) scan viewed in BeTSI.

The TriDAR is a hybrid sensor capable of acquiring long range and short range data. The long range data detects objects sized 1 to 2 cm at ranges of approximately 80 m by TOF analysis. The short range data detects objects in the submillimeter size range, up to approximately 10 m in distance by a triangulation calculation. TOF and triangulation data are viewed and manipulated using BeTSI. It is possible to rotate, zoom, select an area and obtain its co-ordinates, and take physical measurements using BeTSI.

Two algorithms have been created to incorporate the geotechnical filter into an autonomous site selection decision. These algorithms are run on Xiphos Technologies hybrid processor card (HPC) software on data obtained by the TriDAR. The algorithms produce two distinct colour images from the scan data. The colour scale that is used represents the suitability of an area for excavation, from excellent to poor (Fig 6). In most cases, a lower value on the scale indicates a preferable site.

Figure 5 BeTSI view of Scan Data for Drill Site selection

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Figure 6 Algorithm Colour Scale

A calculation spreadsheet has been developed by Neptec to enable quick determination of the location of a potential drill site. Data from BeTSI, as well as from the roughness and normals images can be input into the spreadsheet to obtain coordinates for an area of interest relative to the TriDAR sensor.

Figure 7: Scan 12 Range and Bearing Calculations

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A. Demonstration Activities The EPLORE system was deployed during an Analogue Field Test conducted in Hawaii November 2008. The

system was used in conjunction with the NASA RESOLVE prospecting system, mounted on a CMU rover (Scarab). RESOLVE consisted of a drill and sample acquisition system, a crusher and a chemistry analysis suite all mounted on Scarab. EXPLORE was used to select the drill hole locations for the field test.

The chemistry plant of RESOLVE was limited in the amount of water the system could tolerate. The amount of moisture present in the material that was drilled and then crushed as a feed to the chemistry plant was thus required to be below a particular maximum. To ensure this, the native Hawaiian soil was dried and then placed in drill tubes, which were reinserted into the ground for drilling. Alternately, when pristine in situ material was drilled, the material was not fed into the chemistry plant.

In the expected use of the EXPLORE system, the objective is not to locate one particular spot, but rather a prospective drilling location. In this instance, it was important to locate the specific drill tube. To ensure the drill tube could be identified from the surrounding soil, it was buried with a small portion exposed. Prior to the initial long range TOF scan, the rover was positioned approximately 8 to 12 m from the prospective drilling location.

Scans obtained during the demonstration were initiated from CSA HQ by connecting to the HPC/TriDAR with BeTSI and commencing the long range scan of the area.

Following scan initiation, the acquired data was processed on board the HPC; this included compression of the raw data for transmission as well as running the site selection algorithms. Connection was established with the HPC web server. The tridar file and the jpeg images were then downloaded at PTOC for analysis. Approximate time from scan initiation to file download completion was 10 minutes.

The region was assessed with EXPLORE and coordinates were obtained using the system spreadsheet. The spreadsheet is designed to compensate for the 15 degree tilt of the TriDAR when installed on the Scarab as well as for the 1.1m nominal distance between the TriDAR sensor and the drill. For the long range scans, an approach offset of 3 or 4 m was input in the spreadsheet to leave appropriate distance from the drill tube in order to perform the short range scan. The operator issued commands to the rover remotely from CSA HQ. This included entering the calculated rover command distances and bearing and initiating the positioning commands to traverse the first approach. This resulted in the rover approaching within 2 metres of the drill site.

Following the rover’s initial traverse, a short range scan was initiated from CSA HQ using BeTSI. Under normal circumstances, the margin of error for positioning the drill over a selected site would be within 0.5m2. In this instance, it was essential that the drill be centred within the circumference of the 8 inch drill tube to ensure that the drill did not encounter the side of the tube during the drilling process. Consequently, an approach offset of 0 m was input into the spreadsheet for remotely directing the rover precisely above the selected site.

B. Results The site coordinates for rover navigation were obtained using BeTSI to ensure accurate results for the purposes

of the demonstration and to objectively analyze the results obtained with the algorithms. Evaluation of the algorithm images was performed following drill initialization.

The algorithms autonomously incorporate two geotechnical criteria into the site selection process. Those are roughness or surface texture of the area and slope. Evaluation of the algorithms consisted of identifying certain surface features and inspecting the potential drill site. Figure 8 depicts the identified drill tube as viewed with BeTSI, and Figure 9 is a roughness image of the same scan data, identifying the drill tube. Figure 10 is the scan data processed with the normals algorithm, and does not clearly show the drill tube. Note the large rock is visible in each image.

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Figure 8: Scan 12 Point Cloud in BeTSI

Figure 9: Scan 12 Roughness Image

Identified rock in the scanned area

Selected site (drill tube)

Identified rock in the scanned area Selected site (drill tube)

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Figure 10: Scan 12 Normals Image

The roughness image, where the drill tube is identifiable, was used to select an area of interest as opposed to the normals image, in which the drill tube is not identifiable. A pixel was selected in the approximate centre of the drill tube. The X and Y coordinates obtained were entered into the appropriate section of the range and bearing spreadsheet. 1. Identification Slope

An important observation regarding regional slope can be seen in the following figures. Figure 11 shows TOF scan in BeTSI, not manipulated, in plan view. Note the questionable surface feature in the top left corner of the point cloud. This area was detected by its dark grey colour rather than black.

Figure 11: Scan 24 Plan View

Figure 12 shows the same scan tilted slightly to show a partial isometric view. It is possible in this view to identify some form of directional slope, though a measurement of the degree is not possible. Note the questionable surface feature from Figure 11 can now be identified as undesirable.

Identified rock in the scanned area

Questionable surface feature

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Figure 12: Scan 24 Partial Isometric View

Figure 13 depicts an end view of scan 24. This image has been tilted only, and not rotated. The undesirable surface feature is still detectable in spite of the slope of the terrain. A measurement of the angle between a plane in the point cloud and the horizontal indicate a regional slope of 19°.

Figure 13: Scan 24 End View

Figure 14 is the product of the roughness algorithm being run on scan 24. The measurement of roughness is mapped to the colour scale described eearlier. Lack of data is shown in black. The undesirable surface feature detected using BeTSI is distinguishable by the red patch in the image, the red indicating that the area is quite rough and would not be a viable drill site. The green in the image represents smooth areas.

Undesirable surface feature

Undesirable surface feature

Slope approximately 19°

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Figure 14: Scan 24 Roughness Image Figure 15 is the product of the normals algorithm being run on scan 24. This algorithm quantifies the degree of slope in the region and is mapped to the colour scale, with lack of data shown in black. The undesirable surface feature detected using BeTSI is still distinguishable by the red patch in the image. The red in the image identifies an area with a slope approaching 90°, which is not desirable (ideal slope is <60°). The level of blue in the image represents a regional slope of approximately 20°, comparable to results obtained with BeTSI. The direction of the slope has very important implications for the mobility platform, in terms of levelling. A useful indicator in determining slope direction from the jpeg images is the lack of data in the bottom right portion of the image. TriDAR’s field of view was only a few meters on the right side due to the fact that the terrain sloped upward to the right of the rover. It may not be possible in all cases to determine slope direction from absence of data as the TriDAR’s field of view will vary with the degree of regional slope. There may be scenarios in which there is regional slope, but full presence of data.

Figure 15: Scan 24 Normals Image

2. Evaluation of Coordinates Obtained

The DrillSiteSelect software that is used to process the scan data processes TOF data. The triangulation data is better suited for close range scans, and the software does not process triangulation data. For this reason, only the long range TOF scans have been compared to the algorithm images for the purpose of obtaining coordinates. Long range drill site inspection involves a larger area and its assessment is more time consuming. During initial algorithm development, TOF data was determined to be the most important dataset with which to begin automation of the site selection process.

Undesirable surface feature

Undesirable surface feature

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A comparison of the coordinates obtained by the algorithm images and those obtained by the use of BeTSI indicate standard deviations ranging from 0.016 to 0.257. The low standard deviation essentially indicates that the results obtained with BeTSI are very similar to those obtained using the algorithms. This may be due to operator inexperience with the algorithm images. These images are an important step in the path to autonomy and are still in the early stages of development. It is possible to obtain site coordinates from the images, but not possible to view and manipulate the data in three dimensions as with the TriDAR point cloud viewed with BeTSI. 3. Rover Positioning

Though rover navigation was not expected to be a remote operation for this demonstration, the operator at CSA HQ initiated navigation commands. Prior to initiating a scan, connection was established with Carnegie Mellon University’s Scarab control web application. Rover commands included entering the calculated rover command distances and bearings, initiating the positioning commands, and lowering the rover to the drill position. After analyzing the scans with EXPLORE, and obtaining range and bearing coordinates, the command information was input to the Scarab’s control web application. The range and bearing commands were provided relative to the TriDAR’s current location. The Scarab control web application reported completion when the rover was in place.

Following the long range scan and rover navigation, the TRIDAR’s triangulation laser was connected by Neptec personnel in Hawaii. A triangulation scan was performed. A second EXPLORE analysis was performed and commands issued to the rover through the web application. Once the rover was in position over the drill tube, Scarab was leveled with respect to gravity and the body was lowered to an appropriate distance from the ground. Again, the Scarab web application reported completion of the issued commands. Drilling began following confirmation of appropriate rover positioning by personnel on site in Hawaii.

IV. Next Stages of Development A method is being investigated to use the geotechnical criteria on returned GPR and/or fused GPR and vision

system data. GPR will be used to verify a selected site. It is likely the criteria used to evaluate this data will be similar to the excavation site selection criteria that are currently used.

The development of vision system requirements has been driven by the geotechnical criteria. However, not all of the criteria are applicable to the vision system. For example, identifying a dust sized particle is extremely difficult, and requires the use of a microscope. It is also difficult to distinguish between dust size material and some bedrock outcrops in the returned TriDAR data. As such, NORCAT and Neptec are working collectively to evolve the criteria in such a way to be used specifically as vision system requirements. This may involve the addition and/or deletion of certain elements of the criteria in order to obtain the highest quality and greatest amount of information possible from the returned vision system data.

Further development includes evaluating the potential to incorporate the access way placement criteria into the excavation site selection criteria. The geotechnical criteria is a useful tool that could be rendered very powerful by incorporating as much information as possible into one list of criteria that is simple to use. Terrestrially, a comprehensive geomorphological evaluation technique for use in environmental and civil engineering when investigating the feasibility of a certain construction site selection has been envisioned for a number of years. EXPLORE’s geotechnical criteria could provide planetary and terrestrial engineers the necessary information to select sites for a variety of purposes.