FINAL DESIGN REPORT LUNAR EXCAVATOR NASA CORP 1 GROUP MEMBERS Nathan Bender Allen Craven John Daniels Chris Lambert Taylor Wingo Rob Mueller NASA Sponsor Dr Beale MECH 4240 Comprehensive Design One Spring 2008 1 1 0 ABSTRACT The objective of this design project was to design and develop a second generation lunar excavator The purpose of the excavator is to excavate lunar regolith in order to extract oxygen and other elements that are vital to sustain life in a lunar environment The three main design challenges that the second generation excavator intends to solve are 1 The excavator must interface with the KSC interface plate 2 Design the excavator with materials that are able withstand the lunar environment 3 Incorporate a vibratory bit in the new design of the excavator When designing the new excavator the design specifications and constraints from the first excavator were kept in mind The excavator mass must be less than 100 kilograms power consumption must be no more than 100 watts and must be able to excavate regolith at a rate of 300 kilograms per hour The main design issue facing the excavator is the incorporation of the vibratory bit The purpose of the bit is to break up loosen the regolith grains which allows for easier excavation Initial concepts were composed of a square tube bit with a simple voice coil to provide the forced vibration However after further design concepts were developed a square tube bit with a translating shovelhead design was ultimately decided upon To begin the first generation excavator was tested in order to find the main problems or issues that the original excavator was facing The main issues from the first excavator were the interface height angle and the inability to scoop or excavate dirt regolith In order to design for the lunar environment five main areas were researched They were the lunar environment and thermal conditions operable materials in the lunar conditions motors actuators operable in lunar conditions and bearings and hardware operable in lunar conditions From thorough research appropriate components were determined to be applied to feasible concepts that were developed 2 Table of Contents 1 0 ABSTRACT John Daniels 2 2 0 INTRODUCTION Allen Craven 7 3 0 DESIGN SPECIFICATIONS AND CONSTRAINTS 8 4 0 5 0 3 1 Design Specifications Allen Craven 8 3 2 Design Constraints John Daniels 8 CONCEPT PRESENTATION 11 4 1 Interface John Daniels 11 4 2 Frame and Support Members John Daniels 12 4 3 Bit Adjustment John Daniels 13 4 4 Bit Vibration Chris Lambert 14 4 5 Material Selection Allen Craven 17 4 6 Regolith Removal Allen Craven 18 ENGINEERING ANALYSIS Chris Lambert 20 5 1 Bit Calculations Nathan Bender 21 6 0 ECONOMIC ANALYSIS John Daniels 24 7 0 CONCEPT RECOMMENDATION John Daniels and Taylor Wingo 27 8 0 CONCLUSIONS John Daniels 29 REFERENCES Allen Craven 31 APPENDIX I LUNAR ENVIRONMENT CHARACTERISTICS Nathan Bender 32 APPENDIX II SOIL AND ROVER FORCE CALCULATIONS Nathan Bender and Allen Craven 36 APPENDIX III MAXIMUM IMPACT FORCE Taylor Wingo 44 APPENDIX IV ELECTRONICS SCHEMATIC Nathan Bender 45 APPENDIX V LINEAR VOICE COIL Chris Lambert 46 APPENDIX VI LINEAR ACTUATOR BIT Nathan Bender 50 APPENDIX VII LINEAR ACTUATOR FRAME Nathan Bender 51 APPENDIX VIII ELECTRONIC CONTROL KEYLESS Nathan Bender 52 APPENDIX IX CONVEYOR SYSTEM Nathan Bender 53 APPENDIX X LINEAR BEARING Taylor Wingo 54 3 APPENDIX XI VIBRATION ISOLATION Taylor Wingo 55 APPENDIX XII KAPTON TAPE Allen Craven 56 APPENDIX XIII GANTT CHART SCHEDULE John Daniels 57 APPENDIX XIV SOLID EDGE DRAWINGS All 58 4 List of Figures 4 1 1 New Mounting Interface 12 4 1 2 Old Mounting Interface 12 4 2 1 Frame Support Ends 13 4 3 1 Bit Adjustability 14 4 4 1 Vibratory Bit View 1 15 4 4 2 Vibratory Bit View 2 15 4 4 3 Vibratory Bit View 3 16 4 4 4 Vibratory Bit Top View 16 4 4 5 Vibratory Bit Back View 17 4 6 1 Sketch of Regolith Collection in Bin from Conveyor 19 5 1 1 Total Force as a Function of Depth 21 5 1 2 Regolith Density Properties 22 5 1 3 Total Force as a Function of Rake Angle 22 7 0 1 Overall Concept 27 5 List of Tables 6 0 1 Cost Analysis for Space Qualified Materials and Parts 24 6 0 2 Cost Analysis for Terrestrial Materials and Parts 25 6 2 0 INTRODUCTION This project was completed under the purview of Auburn University and NASA KSC The supervising faculty member at Auburn University was Dr David Beale The sponsor contact was Mr Rob Mueller Surface Systems Lead Engineer Advanced Systems Division This report details our efforts to design a second generation lunar excavator NASA is very interested in the prospect of lunar excavation for the future Not only will this process be for terraforming the lunar surface but the harvested lunar regolith will be used for the extraction of oxygen from the abundant silicon oxide aluminum oxide and titanium oxide that exist in the lunar soil The proposed design will be attached via KSC interfacing plate to a NASA Scout Rover used to explore the lunar surface Due to the nature and cost of space missions NASA wants a low cost excavator low in weight and power requirements that removes regolith at a rate of 300 kilograms per hour The design herein utilizes the motion of the rover itself to push a vibrating translational blade The regolith will be driven up the blade where it falls onto a conveyor that dumps the soil into a storage bin 7 3 0 DESIGN SPECIFICATIONS AND CONSTRAINTS 3 1 Design Specifications The design objective is to design a second generation lunar regolith excavator based upon the platform from the first generation concept Based upon testing in the USDA soil bin propose design modifications at the concepts presentation to improve performance These modifications should be presented via Solid Edge drawings The sponsor desired the incorporation of a vibratory bit The bit should allow for variable frequency and isolate the bit vibration from the rest of the excavator Test using a regolith substitute that is expected to have similar characteristics as the lunar regolith The first generation prototype was unable to achieve the low angles to the ground that were desired during testing Newly design or redesign whatever is necessary in order to achieve the necessary angles and be mindful that the excavator will need to fit onto the KSC interfacing plate Review past NASA literature and other literature regarding design engineering issues that need to be eventually addressed when designing and building lunar machinery These issues should include