OSIRIS-Rex MISSION

Home , Athena (spacecraft), Lucy (spacecraft), Systems Tool Kit

INTEGRATED MODEL-BASED SYSTEMS ENGINEERING (MBSE) APPLIED TO THE SIMULATION OF THE OSIRIS-REx MISSION

Phathom Athena Donald Systems Engineer

© 2018 LOCKHEED MARTIN CORPORATION. ALL RIGHTS RESERVED OSIRIS-REx MISSION OVERVIEW Origins Spectral Interpretation Resource Identification and Security-Regolith Explorer Overview Challenges (OSIRIS-REx) Objectives • Visit near-Earth asteroid called Bennu and return with Approach samples that may contain clues to the origins of the solar Modeling system and possibly life itself. Simulating • Determine Bennu’s physical and chemical properties. Results • Globally map the topography and mineralogy of Bennu. Reflections • Measure the orbit deviation caused by non-gravitational Future Work forces. • Compare observations made at asteroid to ground-based observations.

Overview Challenges Objectives Approach Modeling Simulating Results Reflections Future Work • Need to avoid sun in the Thermal KOZ and in the +Z area of the spacecraft. • Thermal constraints assert sun cannot be in Thermal KOZ past a certain duration threshold. © 2018 LOCKHEED MARTIN CORPORATION. ALL RIGHTS RESERVED 3 OBJECTIVES Previous Operations Process • Use of GNC prediction software that provides review of Overview constraint violations. Challenges • Objectives Run through SoftSim testbed. Approach • Cannot easily identify spacecraft constraint violations until Modeling mid-development. Simulating New Operations Process Objectives Results • Rapidly evaluate various trajectories for thermal constraint Reflections violations to identify preferred mission trajectory. Future Work • Provide quicker, more flexible approach for assessing geometry constraints during early stages of mission planning. • Efficiently track variables during proposed OSIRIS-REx trajectories. © 2018 LOCKHEED MARTIN CORPORATION. ALL RIGHTS RESERVED 4 APPROACH SysML Model + MBSE Analyzer Systems Tool Kit (STK) Simulation Overview Settings & Challenges Constraints Objectives Approach Modeling

Simulating Simulation Settings & Constraints Results ModelCenter Data Explorer Reflections STK & MC Future Work Simulation Results

Overview Challenges Objectives Simulation Settings Approach & Constraints Modeling Simulating Structure Results Reflections Future Work

Overview Challenges Objectives Approach Modeling Simulating Results Reflections Future Work • The constraint block in the architecture model points to ModelCenter workflows using MBSE Analyzer. • MBSE Analyzer within MBSE Pak solves the parametric diagram by linking it to the model in ModelCenter that consists of scripts and the STK component. © 2018 LOCKHEED MARTIN CORPORATION. ALL RIGHTS RESERVED 7 SYSTEMS TOOL KIT (STK) • To express the Sun vector’s azimuth and elevation in reference to the Body Axes, the vector is projected onto the Body XY plane, Overview creating the red “SunOnXY” vector. Challenges • The angle between SunOnXY and Body X is the “SolarAzimuth”. Objectives The angle between SunOnXY and Body Z is the “SolarElevation”. Approach Modeling Simulating Results Reflections Future Work

Overview Challenges Objectives Approach Modeling Simulating Results Reflections Future Work

• The scenario results are linked to scripts defined in ModelCenter for determining any constraint violations.

© 2018 LOCKHEED MARTIN CORPORATION. ALL RIGHTS RESERVED 9 SIMULATION PROCESS OVERVIEW 1. Enter simulation settings 2. Initiate simulation from 6. Evaluate STK parameters; and constraints. MBSE Analyzer. return results to MBSE Analyzer. Overview Challenges 7. Display simulation results for Objectives each time step. Approach Modeling Simulating Results Reflections Future Work

5. Retrieve parameter 4. Point to external 3. Step through the mission values from STK. analysis tools. simulation. © 2018 LOCKHEED MARTIN CORPORATION. ALL RIGHTS RESERVED 10 SIMULATION RESULTS & REQUIREMENTS VERIFICATION

Overview Challenges Objectives Approach Modeling Simulating Results Reflections Future Work • System-level and subsystem-level states captured in value properties. • Requirements verification captured in value properties. • Values stored at each time step and displayed in Data Explorer. © 2018 LOCKHEED MARTIN CORPORATION. ALL RIGHTS RESERVED 11 REFLECTIONS MBSE Advantages Challenges Encountered • Could not express time in Overview • Formal, accurate system- level model capture. UTCG without STK Object Challenges • Early identification of Model. (resolved in STK11) Objectives requirements issues. • No requirements Approach • Early, and on-going verification at each time Modeling requirements and design step. Simulating verification. • Dot notation not allowed on Results • Improved impact analysis of parametric diagrams. Reflections requirements changes. Lessons Learned Future Work • Interconnectivity and reuse • The STK Programming of existing models to Interface allows for great support system design. flexibility. • Rapid re-evaluation when • Collaborating with vendor design changes occur. tech support is imperative.

Overview • Include downlink duration and momentum buildup Challenges • Extend and refine the behavioral and analysis models Objectives • Improve approach for plot generation Approach Modeling Simulating Results Reflections Future Work

• Enable sensitivity analysis and design optimization • Implement analysis integration for NASA’s Lucy mission

Architecture Model SIMULATION SETTINGS & THERMAL CONSTRAINTS • Simulation time Overview settings and system Challenges thermal constraints are captured in the system Objectives model. Approach • This facilitates Modeling requirement and Simulating constraint changes for Results efficient impact Reflections analysis. Future Work

Overview Challenges Mission Level Objectives Approach Modeling Simulating Results Reflections

Future Work Vehicle Level

© 2018 LOCKHEED MARTIN CORPORATION. ALL RIGHTS RESERVED 16 Architecture Model PARAMETRIC DIAGRAM • Using MBSE Pak, value properties are bound to a constraint block that links to Overview a model in ModelCenter that contains scripts and a STK Challenges component. Objectives • Inputs to STK: • Analysis Start Time Approach • Analysis Stop Time Modeling • Time Step Size • Outputs from STK Simulating • Solar Elevation Results • Solar Azimuth • Solar Range Reflections • Earth Range Future Work • Bennu Range • SAP Angle • SPE Angle • Outputs from ModelCenter • KOZ in Sun • Duration of thermal violations

Update states Overview and value properties Challenges Objectives Approach Modeling Simulating Results

Reflections Loop Simulation from Analysis Future Work Start Time to Update time Analysis Stop Time