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Ae105c Term Project Design Review MA’AM June 7, 2007. Mars Advanced Attack Mission. Teams. Trajectory Paul Hebert Ashley Moore Jack Ziegler Structures and Configuration Devvrath Khatri Francisco L ópez Jiménez Celia Reina Romo Thermal Annamarie Askren Philipp Boettcher Angie Capece

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## Ae105c Term Project Design Review MA’AM June 7, 2007

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**Ae105c Term Project Design ReviewMA’AMJune 7, 2007**Mars Advanced Attack Mission 1**Teams**• Trajectory • Paul Hebert • Ashley Moore • Jack Ziegler • Structures and Configuration • Devvrath Khatri • Francisco López Jiménez • Celia Reina Romo • Thermal • Annamarie Askren • Philipp Boettcher • Angie Capece • Olive Stohlman 2**Review Board**Greg Davis Rob Manning Jay Polk Marco Quadrelli Mike Watkins Paul Dimotakis 3**Mission Overview and Requirements**If JPL could land 200 kg on MARS, can we land 20 kg?**Outline**• Introduction • Analytical Work • Trajectory • Thermal • Structures & Configuration • Conclusion**Mission Overview and Requirements**Mission Statement: Design a trajectory, thermal system, and structure system for a Mars Network Lander that safely delivers a 20 kg payload to Nili Fossae. Level 1 requirements 6**Payload Overview and Requirements**The payload allows visualization of the Martian environment, analysis of Mars’ atmosphere and weather patterns, as well as the on-going search for water on Mars. 7**Design Assumptions**• Used previous work (MER, Pathfinder) as design starting point • Scaled MER in mass and volume to match our design requirements • Verified our model results with data from these missions • Used first-order approximations to model the design and make design decisions 8**System Evolution**• Satisfy the requirements • Reliable and affordable Viking / MER heritage • Delta II launch vehicle: maximum aeroshell diameter ≈ 2.5 m General ideas for the design 9**Final Configuration**BACKSHELL PARACHUTE AND CANISTER PAYLOAD PAYLOAD PROTECTION HEATSHIELD 10**Final Configuration**0.845 m 70 deg 1.10 m 11**EDL Sequence**12**EDL Sequence**13**Final Configuration**Payload Crushable material Payload Separation Bolts 14**Notional Design of Instrument Setup**• Partially Isotropic Payload • Telescoping Weather Boom • Visible Wavelength Camera with Mirror System • Surface Water Detection System Cut View of P/L 15**Trajectory**Paul Hebert, Ashley Moore, Jack Ziegler Presented by: Jack Ziegler 16**Trajectory Overview**• Tasks • Model entry vehicle using Matlab, separation to impact • Disperse nominal trajectory for landing ellipse • Supply to thermal team • As Functions of time: • Altitude • Angle of attack • Free stream velocity • Density Profile • Dynamic pressure • Supply to structures team • Terminal velocity and orientation at impact • Body accelerations in flight • Landing Ellipse Requirements • Along-track error +/- 50km • Cross-track error +/- 5km • Receivables • Vehicle shape • Center of mass, inertias • Aerodynamic models • Parachute size • Heat shield mass 17**Dynamic Model Assumptions**• Aerodynamic coefficients (Lift, Drag, Moments) • Hypersonic Model (M>5) • Cd: Supersonic and transonic models • Subsonic Mach # gaps, using MER data • Parachute • Deploy at Mach 1.8, • ->Cd 0.4, radius 7.5m • (linearly increases in 2 secs) • Mass loss • Drop 45 kg mass at • Mach 0.95 • Spherical planet model (neglect oblatness, rocks, mountains, etc.) • Rigid atmosphere/planet model • (atmosphere moves with planet) • No wind gusts • Two density models • (avg. Mars day) • Simple exponential: h=125-55km, Table: h<55km • Uniform gas properties (C02) 18**Nominal Non-Dispersed Initial Conditions**Altitude: H = 125 km Latitude: = 13.67o Longitude: = 73.8o Bank Angle = 0o Flight Path Angle = -10o Heading Angle = 0o X velocity: U = 4.5 km/s Y velocity: v = 0 km/s Z velocity: W = 0 km/s Roll rate: p = 0 deg/s Pitch rate: q = 0 deg/s Yaw rate: r = 0 deg/s • 12 Dynamic • Degrees of Freedom • Translation • Orientation • Linear Velocity • Angular Velocity Enters Atmosphere from S N Polar Orbit Similar velocity &flight path angle of Viking Missions 20**Dispersion Motivation and Assumptions**Created Dispersion Analysis (Monte Carlo) - Models the uncertainties and errors - 500 random simulations Dispersed (perturbed) initial states and parameters - Values similar to MER dispersion Random Gaussian Dispersion - Gaussian distributions - Centered at nominal with 3 max Created landing ellipse - Obtained from all dispersed locations of impact. Notes: Did not calculate the 3 ellipse (enclosed all points) Approximate size of ellipse calculated from all impact locations projected onto a plane in the vicinity of Nili Fossae 21**Description of the Monte-Carlo code**Values taken mostly from “MER EDL Trajectory Analysis”, N. Desai 22**Dispersion Results**Impact Velocity Distribution Number of Cases Impact Velocity 23**Altitude**- Quick descent in low density region - Increasing deceleration with exponential increase in density 25**Velocity of Free Stream**Nominal Impact Velocity = 24 m/s Parachute deploys 26**Orientation**Note the switch from fast to slow oscillations at parachute deployment 27**States from Numerical Integration**Output from Matlab ode15s (“stiff” adaptive time step integrator) 28**Aerodynamic Drag and Lift**Cd fairly const. for M > 5 Increases near Transonic 0.4 for parachute note spike when parachute deploys CL function of Angle of attack 29**Latitude and Longitude**Approaching the Landing Site: Nili Fossae (latitude=20.93N, longitude=74.35E) 31**Trajectory Relative to Inertial Frame**Time = 0 to 50 sec Non-Rotating Inertial Frame at center of planet Entry Vehicle displayed at constant time intervals 32**Trajectory Relative to Inertial Frame**Time = 50 to 100 sec 33**Trajectory Relative to Inertial Frame**Time = 100 to 150 sec Note the rapidly decreasing flight path angle 34**Landing Ellipse**• 500 Randomly Dispersed Trajectories • Nili Fossae 47.7 km 20.6 km 35**Summary of Nominal Trajectory Results**Impact Velocity V = 24 m/s t=~150 secs Max in flight acc. ax = 20g, ay = 10g, az = 60g (Off b/c of hypersonic aero. moments invalid) Landing site Altitude: h = 1 km Latitude: = 74.35 Longitude: = 20.93 Landing Ellipse Major axis: 47.7 km Minor axis: 20.6 km • Dispersion References • Desai, P. N. and Knocke, P. C. “Mars Exploration Rovers Entry,Descent, and Landing Trajectory Analysis.” AIAA. • Desai, P. N., Schoenenberger, M. and Cheatwood, F. M. “Mars Exploration Rover Six-Degree-Of-Freedom Entry Trajectory Analysis,” Proceedings of the AAS/AIAA Astrodynamics Specialists Conference, August 3-7, 2003, Big Sky Resort, Big Sky, MT, AAS 03-642. 36**Thermal**Annamarie Askren, Philipp Boettcher, Angie Capece, Olive Stohlman Presented by: Olive Stohlman 37**Thermal Overview**Requirement: Maintain the P/L between 5˚C and 35˚C Approach: Determine the dynamic and integrated heat loads Design the ablator Volume Shape Materials Determine the heat load to the structure and P/L Prevent inner shell materials from melting Sustain attachment mechanism (bondline temperature) 38**Assumptions**• Reliance on previous work (MER, Pathfinder, …) for cross-checking our results • 1-D numerical analysis to determine conductive heating of payload 39**Model Comparisons**• Regan • (1984) • Corning • (1964) • Hankey • (1988) • Sutton • (1971) • Tauber (radiative)**Convective and Radiative Heat Loads**Pathfinder 4.5 km/s 5.6 km/s Our Design Convective Heat Rate: 260,000 W/m2 Radiative Heat Rate: 20,000 W/m2 Used chart above to verify analysis by cross-checking with MPF 41**Mars Re-entry Mission Data**Wright, M.J., Edquist, K.T., Hollis, B.R., Brown, J.L., Olejniczak, J., “A Review of Aerothermal Modeling for Current and Future Mars Entry Missions,” Draft paper for submission to AIAA Journal of Thermophysics and Heat Transfer – February 2007**Ablation Design**Ablation Material: SLA561V* Effective Heat of Ablation: 5.41 x 107 J/kg Material Density: 264.3 kg/m3 Specific Heat Cp: 1.16 x 103 J/(kg-K) Nominal Ablation Thickness: 1.6 cm (using Sutton) Constant Ablation Profile *TPSX Materials Properties Database. NASA. http://tpsx.arc.nasa.gov/ 43**1-D Heat Conduction Analysis**Assumes: Simplified payload-heatshield interface Upper bound on heat load Sutton + 30% Entire structure begins at payload minimum temperature (5˚C) Lower than true value of heat of ablation (80% of theoretical values) for SLA 561 Unknown: • Actual temperature of ablation of SLA 561 • Assumed 4000 K (Quartz: 2700 K) • Char layer behavior • Assumed no char layer left 44**1-D Heat Conduction Analysis**Finite Element Model Confirms glue line temperature under 250˚C (220˚C), payload temperature under 30˚C 1-D Position vs. Temperature 1-D Position vs. Temperature (Zoom) Temperature [K] Temperature [K] Distance from Payload [m] Distance from Payload [m] 45**Thermal Final Design**Total Heat Load 1.1 x 107 J Ablator Material: SLA561 Thickness: 1.6 cm Safety Factor: 2 Mass: 4.3 kg Bondline Temperature 230 ºC Payload Temperature 6 ºC 46**Structures & Configuration**Devvrath Khatri, Francisco López Jiménez, Celia Reina Romo Presented by: Francisco López Jiménez 47**Impact calculation**Honeycomb as crushable material: uniform, predictable and efficient *Hexcel energy absorption systems Assumptions: Stroke 80 % of honeycomb thickness Type Cross-Core: multi-directional energy absorption Precrushing to eliminate peak load Constant force: 700 g 48**Impact calculation**Calculation kinetic energy energy absorbed before impact by crushable Nominal 3-sigma Note: solution for elastic (harmonic response) = 49**Impact calculation**Final design crushable material 1/4 -5052-5.2 CRIII Aluminum HexWeb (1300 kPa) 10 cm thickness 200 % margin for nominal case in stroke 25 % margin for 3-sigma case in stroke maximum load 700g 40 % margin 50

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