LunarDREEM Preliminary Design Report

1. LunarDREEM Preliminary Design Report Source: aerospacescholars.jsc.nasa.gov March 10th, 2005 Jessica Thompson

2. Presentation Outline • ISOP System • Summary of results from Conceptual Design Report Trade Study • Electrolysis System Design • Oxygen Storage Tank Design • Radiator Design • Hydrogen Recycling Trade Study • Furnace Design • Process for Further Design Iterations • Excavation System • Summary of Concepts • Analysis of Conveyor Belt Concept • Analysis of Drill Concept • Bulk Physical Measurement Systems • Materials Design Considerations Jessica Thompson

3. ISOP System Conceptual Design heat Relief valve • Conceptual Design Trade Study Results: • Possible Batch Sizes: 5kg, 10kg, 20kg • Processing Time: 3 hours Jessica Thompson

4. Electrolysis System Slides Space Holder Alice Zhou

5. Oxygen Storage Tank Design • Assumptions: 3kg oxygen, 20°C operating temperature, Spherical shape • Material Trade Study MaterialYield Strength(Mpa)Density(kg/m3) Beryllium(pure-toxic?) 350 1850 Aluminum 48.3 2768 Super alloyxm-19 127 7750 High strength annealed Aluminum5052 H38 44 2685 Haynes188 103 8968 Aluminum Tread-Brite H18 27 2740.3 Monel K-500 65 8442.3 Becca Arvanites

6. Calculating Tank Mass • Oxygen Pressure = mass*R*Temp/Volume • Radius = [(3/4pi)*Volume]1/3 • Tank wall width = Pressure*Radius/Max yield stress • Tank mass=Density*Surface area*Width • =Density*4pi*Radius2*Width MaterialTank Mass(kg) Beryllium(pure-toxic?) 36.2 Aluminum 39.4 Super alloyxm-19 41.8 High strength annealed Aluminum5052 H38 41.9 Haynes188 59.8 Aluminum Tread-Brite H18 69.7 Monel K-500 89.2 Becca Arvanites

7. Oxygen Tank Results • Lightest (allowably safe) material Aluminum, still much too heavy • Looking into alternative composite material • Should reduce weight of tank by 37%+ • 39kg to less than 25kg Becca Arvanites

8. Radiator Study • Purpose • To find a suitable length and mass for a radiator to condense Heated Water Vapor (900oC) to Condense Water Vapor (95oC) • Assumptions • Total incoming flow value, min will be .002 kg/s • The heat that is released by the water vapor is conducted by aluminum and emitted to space, thus we will calculate the power emitted to space per unit area exposed to the surroundings. • Temperature of the surroundings will be 40 K • Efficiency of the radiator will be around 90% James North

9. Radiator Study • First, the thickness of the aluminum must be found since we know that the heat generated by radiation should be equal to the heat generated by conduction. • The aluminum tubing will be cover with Multi Layered Insulation which will allow for the use of MLI’s thermal conductivity to be used to find the thickness. Thickness = -K∙( Tsurroundings - Twater)/[ε∙σ∙(Twater4 – Tsurroundings4 )] Thickness = 1.055 x 10-5 m James North

10. Radiator Study • Calculations • Iteration process of ΔT = 1 as T > 95oC (368 K) Power/Area = ε∙σ∙(Twater4 – Tsurroundings4 ) Cp=143.05 - 183.54∙(T/100).25 + 82.751∙(T/100).5 - 3.6989∙(T/100) Length=[min∙Cp*(T - ΔT )] /[η∙2∙π∙router∙(Power/Area)] Mass=ρ*π*(router2-rinner2)∙Length James North

11. Radiator Study Length = .1772 m Mass = 8.06 x 10-4 kg James North

12. Radiator Study • Must taken into consideration lunar regolith covering the MLI during operations • Assume the efficiency of the radiator to drop to 80% • Outside regolith may adversely affect the temperature of condensed water vapor exiting the radiator • Very important to not have that temperature bet 0oC James North

13. Radiator Study η = .9 T= 5oC Length = .1956 m T= 95oC Length = .1772 m η = .8 T= 5oC Length = .2201 m T= 95oC Length = .1993 m Operating Length will be .2 m Operating Mass will be 9.09 x 10-4 kg James North

14. Trade Study on Recycling Hydrogen • Hydrogen mass flow: H2tank-->Furnace--> (with water vapor) through radiator--> Electrolyzer-->Recycling tubing-->Pump • mass flow=.01kg/s, flow velocity=.01m/s Flow v >.01m/s Furnace Electrolyzer H2 Mass flow=.02kg/s Mass flow=.0198 kg/s O2 Becca Arvanites

15. Hydrogen Furnace Flow • Needed to check flow velocity >.01m/s in furnace: Area = mass flow/(density*velocity) • for mass flow of .02kg/s: Area < 22m2 • for flow velocity = .08m/s: Area=2.78m2 Becca Arvanites

16. Hydrogen Recycling • H2 Recycling to reduce tank weight • H2 mass(no recycling)=flow rate*3hours*(#batches)>1000kg • Returning hydrogen includes H2 and hydrogen from water vapor, mass flow=.0198kg/s • For Radius of4.5cm,Velocity is35m/s Becca Arvanites

17. Hydrogen Recycling • Circulating mass H2=H2 flow rate*time • time=distance/flow velocity each section=5.11s • H2 mass = 0.102 kg • Weight of Recycling system =length*pi*width2*densityaluminum • Weight=4.254m*pi*(.005^2)*2768=0.926kg Becca Arvanites

18. Furnace Heating Trade Study: Heating Method • Electrical Resistance Furnace • Microwave Furnace • RHU Technology Based Furnace JoHanna P.

19. Furnace Heating Trade Study: Summary JoHanna P.

20. Furnace Heating Trade Study: RHU Technology Based Furnace • Calculations based on Cassini RHU Performance Characteristics • Mass/RHU: 40g • Thermal Power @ BOL: ~1W • Additional assumption: 80% of the heat generated reaches the regolith • Results: Less than 2.3kg of RHU mass required for the option requiring the highest power levels (10kg batch with a 1hr heating time). JoHanna P.

21. Furnace Heating Trade Study: RHU Technology Based Furnace Design Considerations • RHUs will continuously output heat; thus, heating the inside of the furnace after the regolith has reached the desired temperature. • RHUs will radiate heat in all directions. • RHU geometric distribution around the regolith will impact regolith temperature distribution. • Regolith heating characteristics will impact regolith temperature distribution. JoHanna P.

22. RHU Technology Based Furnace: 0th Order Structural Mass Calculation • Assumptions • Uniform wall thickness of 1/16 in (0.159cm) • Wall material is Ti-6Al-4V • Spherical furnace • Equation • Mass = density * thickness * inner surface area JoHanna P.

23. Place Holder for Parametrics Furnace Mass Curve JoHanna P.

24. ISOPS Design Flow Chart Given: Design Calculations Yield: Hydrogen gas flow requirement (Allen and McKay) Radiator – mass flow rate (kg/s) Furnace hydrogen mass flow (kg/s) Furnace Cross-sectional Area Hydrogen-recycling trade-study Electrolyzer Design Batch Size in Furnace *What we have shown today is the first iteration through this design process Oxygen Tank Design JoHanna P.

25. Presentation Outline • ISOP System • Summary of results from Conceptual Design Report Trade Study • Electrolysis System Design • Oxygen Storage Tank Design • Radiator Design • Hydrogen Recycling Trade Study • Furnace Design • Process for Further Design Iterations • Excavation System • Summary of Concepts • Analysis of Conveyor Belt Concept • Analysis of Drill Concept • Bulk Physical Measurement Systems • Materials Design Considerations Jason Atkins

26. Excavation System • Includes: • Excavator Subsystem to collect regolith • Bulk Physical Characteristics Test Chamber • Delivery System to transfer regolith from Excavator Subsystem to ISOPS • We discuss preliminary designs for the Excavator Subsystem and Bulk Physical Characteristics Test Chamber • Shape and orientation of Bulk Physical Characteristics Test Chamber constrain choice of Delivery System Jason Atkins

27. Excavator Subsystem Concepts • Conceptual Design Trade Study identified two promising concepts: • Conveyor Belt • Drill Jason Atkins

28. Place Holder for Conveyor Belt Slides Jason Atkins

29. Drilling: Power Considerations Constraints: • Drill depth at least 1 meter deep. • 100 kg of Lunar Regolith must be collected. • Maximum Power Usage= 100 W Emmanuel Sin

30. Drilling Strategy • The Drill will have a cutting edge that will allow it to cut into the Lunar Regolith. • As the Drill moves downward, soil will travel up through the flights. • “Peck-drilling” will prevent the flights from filling up with soil and thus prevent the Drill from getting stuck. Emmanuel Sin

31. Drill Concept Although the drill length is constrained to 1m, certain drill specifications can be manipulated to optimize excavator efficiency: - Drill diameter - Flight design (quantity, angle, width) - Cutting edge - Material selection Emmanuel Sin

32. Drill: Power Calculations • P= F*V • P= T*W Requires experimental data! Emmanuel Sin

33. Drill: Mass Calculations Zachary Reynolds

34. Drill: Operational Time Zachary Reynolds

35. Calculations • Number of holes to drill-> radius of each hole -> torque required to drill hole of this radius-> necessary inner radius of drill to bear such a torque -> mass of drill • Assume torque required is proportional to cube of radius of hole • Assume 100W motor ~2 kg (http://scootersupport.com/motors.htm) Zachary Reynolds

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37. Bulk Physical Measurement Systems • Three Concepts: • Compression Chamber • Rotary Bar • Pin Pull Jordan Medeiros

38. Compression Chamber Shear Compartment Compressive Piston Shear Piston Shear Line • Mode of Operation: • Sample is loaded into the chamber and compressed to a desired displacement by the compressive piston. The force required to reach such a displacement is backed out by taking the voltage applied by the actuator to the piston. • A voltage is then applied to the second actuator controlling the shear piston. This voltage is slowly increased until a displacement occurs along the shear line. This voltage represents the force required to yield the material. • Using a set of such measurements, we can construct a stress-strain curve for the material and back out other physical characteristics as well. Jordan Medeiros

39. Rotary Bar Viscosity Tester Compressive Piston Rotary Piston Rotary Bar • Mode of Operation: • Sample is loaded into the chamber and compressed to a desired displacement by the compressive piston. The force required to reach such a displacement is backed out by taking the voltage applied by the actuator to the piston. • A voltage is then applied to the second actuator controlling the rotary piston. This voltage is slowly increased until a displacement occurs along the rotary line. This voltage represents the force required to yield the material in shear. • Using a set of such measurements, we can construct a stress-strain curve for the material and back out other physical characteristics as well. Jordan Medeiros

40. Pin Pull Indentation Test Compressive Piston Indentation Pin • Mode of Operation: • Sample is loaded into the chamber and compressed to a desired displacement by the compressive piston. The force required to reach such a displacement is backed out by taking the voltage applied by the actuator to the piston. • A voltage is then applied to linear actuator controlling the movement of the indentation pin. By comparing the voltage used (which correlates to force), the area of the pin head in contact with the sample, and the depth of the indentation, we can find characteristics such as material hardness using the same methods applied in nano-indentation applications. Jordan Medeiros

41. Bulk Physical Measurement Systems • Pros • All the systems require very few moving parts, significantly lowering the chance of failure • All the systems require very few sensors to back out the required data • All the systems work in any scale, allowing for flexibility in design • Cons • Both the viscosity tester and indentation system are prone to a problem known as frame compliance – the frame of the testing unit, being of finite stiffness, undergoes a displacement when placed in a state of stress. This must be accounted for by calibrating the test unit. • Since it is not known what is the required force to shear the material it is difficult to determine certain design factors – The power of the motors driving the pistons, the required frame material stiffness, etc. • These systems do not get direct measurements of the desired characteristics – these must be found using raw data and calculation software. Jordan Medeiros

42. Other Considerations: Bulk Physical Measurement Systems • Primary factors Affecting physical properties of lunar regolith: • Particle structure and distribution • Bulk density and porosity • Relative density Etienne Toussaint

43. Other Considerations: Bulk Physical Measurement Systems • Particle structure and distribution • Variable that controls to various degrees the strength and compressibility of the material • The structure and void ratio of the particles can be altered through the excavation process • While in the test chamber, the particle structure will directly impact the relative density of the regolith and how easy it to compress it or conduct the rotary tests • All concepts will alter the particle structure during the compression test, which may make it harder to conduct the test for shear force using the rotary bar and wire pull Etienne Toussaint

44. Other Considerations: Bulk Physical Measurement Systems • Bulk density and porosity • The mass of the material within a given volume and the volume of void space between particles • Directly related to particle distribution – if the regolith is densely packed in test chamber with little porosity (would probably occur using drill which grinds soil), bulk density will be high and force required to move the rotary bar or to compress the soil will be great • Conversely, soil that not as fine, or possibly deposited in clumps (tread system) may be more porous and thus, not as dense. Less force will be required for compression and the bar test Etienne Toussaint

45. Other Considerations: Bulk Physical Measurement Systems • Relative density • Again, bulk density of a given soil can vary over a wide range, depending on how particles are assembled • Should take into account when doing various calculations – various ranges of densities possible. Etienne Toussaint

46. Bulk Physical Measurement Systems Etienne Toussaint

47. Bulk Physical Measurements • Excavation System • The drill will grind the regolith into small particles as it moves deeper into the ground, decreasing the amount of void space between particles and thus increasing the relative density. • This will directly effect the force needed to move through the soil and it will cause the soil to be more dense when it is deposited in the test chamber • The tread system will pick up the soil in small chunks, maintaining a more realistic depiction of the density of the soil in the ground. Less problems related to relative density will come into play using this system. Etienne Toussaint

48. Preliminary Materials Selection Conditions to be taken into consideration: • Extremely low temperature • Temperature in shadowed crater assumed to be 40ºK • Extremely low pressure • Atmosphere assumed to be hard vacuum • Abrasive soil • Regolith’s abrasiveness is comparable to that of glass Victoria Harris

49. Preliminary Materials Selection Lubricants1 • Choose interfacing materials that have different crystal structures and atomic sizes • Wet lubrication • Oils will most likely not work in low temperatures • Dry lubrication • Some work in low temperatures (eg molybdenum disulfide) • Shorter service life Victoria Harris

50. Preliminary Materials Selection Metals2 • Most metals will work • E.g. stainless steels, aluminum alloys • Exceptions include nickel steels • Some material properties will change at low temperature • E.g. coefficient of friction • Composites are also a possibility Victoria Harris