AAE450 Spring 2009 Final Slide Concepts March 26, 2009 [Cory Alban] [Mission Ops] [Locomotion] 1

AAE450 Spring 2009 Lunar Surface Hazard Analysis [Cory Alban] [Mission Ops] [Locomotion] Potential HazardSolution Lunar regolith Very fine dry powder Sticks to everything  Using gradual acceleration, the space ball avoids peeling out and digging into the regolith  Vibration Motor shakes off any collected regolith Impact Craters 2cm to several meters in diameter  Choose path to avoid large craters  Built up momentum reduces chance of getting caught in a crater Debris/Rocks Debris size: m to 0.50m  Lexan shell will withstand a full speed collision  At cruising speed, momentum carries ball over small rocks and retains stability (similar to a rolling wheel) Temperature Average day temperature 107C Highest day temperature 123C  Temperatures are within tolerances for Lexan  1atm of N2 inside Lexan shell to control temperature rise within the space ball Temperatures are within thermal range for Lexan 2

AAE450 Spring 2009 Space Ball Structure Analysis [Cory Alban] [Mission Ops] [Locomotion] Bending Moment in Drive Axel Model as a thin circular rod R = 0.125m Aluminum 2024 Alloy σ= 220 MPa ρ= 2730 kg/m 3 Maximum loading conditions (8.3g) g = 8.3 * m/s 2 = 75.25m/s 2 M pay = kg Minimum required radius: 1.17*10 -8 m Torsion Stress in Drive Axel Maximum Torque, T = 0.31 Nm Minimum required radius: 1.10*10 -4 m Design radius: 0.003m Factor of Safety: 27 R M pay *g T 3

AAE450 Spring 2009 Space Ball Structure Analysis [Cory Alban] [Mission Ops] [Locomotion] Sphere Impact Analysis Assume all kinetic energy converted to impact energy Cruise Speed, v = 1.04m/s Ball Mass, m = 2.435kg Total Kinetic Energy, K = 1.317J Impact Strength of Lexan, σ = 600 – 850 J/m Minimum wall thickness: 1.55*10 -3 m Pressure Vessel Analysis Pressure, P = Pa (1atm) Radius of sphere, R = m Maximum Stress of Lexan, σ = 75 Mpa Minimum wall thickness: 8.4*10 -5 m Design wall thickness: 3.82*10 -3 m Factor of safety: 2.5 R 4

AAE450 Spring 2009 Design Concept: Ski Locomotion [Cory Alban] [Mission Ops] [Locomotion] Benefits Passive Suspension System Spring-like qualities Vibration dampening Makes use of regolith While wheels require traction, ski slides over loose surface Downfalls Requires other systems Separate propulsion system Mechanism for turning Additional friction drag Either pushing or pulling skis through regolith Possible ‘tipping’ failure Rise onto a rock, pulling propulsion mechanism off lunar surface 5

AAE450 Spring 2009 Completion of Mission Requirements [Cory Alban] [Mission Ops] [Locomotion] StepTime (min)Tasks to be completed 10 Space Ball performs a system diagnosis. 21 Deployment from Lander. 32 Direction of travel received from mission control. Space Ball orients to path of travel Accelerate to cruising speed of 1.04m/s. Travel for 8 minutes until 500m objective achieved. 511 Braking maneuver with a 90 degree orientation change to point camera toward Lander. Shake off dust if necessary. 612 Snap photo of Lander from ball and begin transmission. 720 Finish Photo Transmission. RequirementSteps to Completion Travel 500m in a controlled manner1-4 Carry 100g payload 500m1-4 Transmit Mission Complete Mooncast6-7 6

AAE450 Spring 2009 Space Ball Overview [Cory Alban] [Mission Ops] [Locomotion] Concept: By offsetting the center of mass inside the ball, a gravity moment causes the ball to roll. Size: Slightly larger than a basketball, the clear polycarbonate sphere has a diameter of 0.25m. Mass: The entire system weights in under 2.5kg! (2.435kg.) Power: The space ball runs on its own power supply nearly the size of a wristwatch battery. It is fully capable of achieving mission objectives on the lunar surface. 7