Gateway to Space AJ - 1 Mechanical System Design & the StarLight Project Andy Jarski Mechanical Systems Engineer Ball Aerospace & Technologies

Gateway to Space AJ - 2 Overview Brief Intro to Mechanical Design process StarLight as an example Some designs I’m working on Conclusions

Gateway to Space AJ - 3 Quick Look at the Design Process Identify the requirements –Mission –Launch Environments –Instrument / Payload Accommodations Create Preliminary Configurations –Subsystem requirements (size, location, FOV) –Accessibility –Producibility –Structural Characteristics (load paths, stiffness) Design Options –Materials (strength, stiffness, weight, CTE, corrosion resistance, cost, etc.) –General shape / layout Validation of Requirements –Test Criteria –Design Criteria Iterations –Until requirements are met Detailed design goes to production

Gateway to Space AJ - 4 StarLight is the 1st of it’s Kind Demonstrate 2 key technologies of particular importance for Terrestrial Planet Finder: –Autonomous Formation Flying –Separated-Spacecraft Interferometry Mission uses 2 spacecraft, launched together which then separate to m to simulate the performance of a single large telescope JPL provides interferometer instruments and formation flying sensors Ball provides 2 spacecraft, integration and test, and operations for the spacecraft Heliocentric, earth trailing orbit to eliminate gravity field perturbations Two spacecraft formation-flying to 2 cm accuracy Low-jitter spacecraft to permit interferometer to lock on fringes

Gateway to Space AJ - 5 Black Magic of Interferometry

Gateway to Space AJ - 6 Formation Flying, in the Dark 26º Half Cones of Shadow (all components are shaded) 42º Starlight View Range Intra Instrument Line of Sight 52º Starlight View Range Collector Optics Combiner Instrument X Collector S/C Combiner S/C

Gateway to Space AJ - 7 Who’s Driving our Configuration? Fit both spacecraft within the 3m, 3 stage, Delta II Fairing Envelope –Interface to the standard Delta 37” clamp band –Keep the CG within launch vehicle limitations Accommodation of Interferometer instruments and Formation Flying Sensors Provide unobstructed fields of view for –StarLight interferometer –intra-interferometer starlight link –Formation Flying sensors –Star Trackers –Antennas –Thrusters –Sun sensors –Solar arrays Maintain CG balance after fuel depletion

Gateway to Space AJ - 8 Launch & Cruise Configurations Delta II 3m-3 Stage Fairing Combiner S/C Collector S/C 37’’ Interface Ring 108” 100” Star 48B 3rd Stage Motor

Gateway to Space AJ - 9 These Spacecraft are Nicely Equipped High Accuracy Formation Flying Sensors Low Impulse Cold Gas thrusters (x16) Star Trackers (x2) Sun Sensors (x14) UHF antennas (Inter s/c comm) Solar Panel 106 in./270 cm dia. Deployable Sunshade 134 in./340 cm dia. Interferometer

Gateway to Space AJ - 10 Interferometer Main Bus Assembly 2-Piece Solar Array Hatch Propulsion Module Modular Designs Reduce Risk Formation Flying Sensor Module Modularity reduces I&T complexity and time required Modularity improves accessibility S/C bus components housed in Main Bus Assembly Instrument is it’s own entity

Gateway to Space AJ - 11 StarLight uses nearly identical composite structures to –closely match the characteristics of the interferometer optical benches –minimize mass Commonality helps to –Reduce I&T complexity –Reduce risk –Lower cost Commonality is Important Relay Box Reaction Wheels (x4) Telecom “gear” X-Band Transponder SCU (Computer) IMU Battery Propulsion “gear” Transceiver Star Trackers (x2) Hatch

Gateway to Space AJ - 12 Structural Requirements Minimum natural frequency of the launch stack –15 Hz Lateral –35 Hz Axial –35 Hz Secondary –Applied to all components except the fixed sun shade Max Axial Load: 9.5 g axial combined with 0.1 g lateral Max Lateral Load: 2.8 g axial combined with 3.0 g lateral Minimum factor of safety –Yield: 1.25 –Ultimate: 1.50 Other requirements (acoustic, random, etc.) not expected to be critical Alignments

Gateway to Space AJ - 13 Launch Configuration Collector Spacecraft Combiner Spacecraft StarLight FEM Finite element models –of Launch Configuration for structural modes analysis –of separated s/c to analyze on-orbit disturbances

Gateway to Space AJ - 14 Modes Analysis 1st Lateral Mode of 15.3 Hz 1st Axial Mode of 38 Hz

Gateway to Space AJ - 15 Connector Separation Spring Separation Nut Separation Plane Deployable is a Dangerous Word Inter-Satellite Separation Mechanisms –Tolerance analysis –Separation dynamics –ABSOLUTELY MUST WORK! Sunshade –Material selection crucial RF transparent Visibly opaque –Stiffness –ABSOLUTELY MUST WORK!

Gateway to Space AJ - 16 Some Other Thoughts Some basic engineering principles I think are important –When you start a design, just get something down on paper –If you leave something as a placeholder, document it as such and make sure to go back and fix it –Allocate lots of time for test, this is where everything comes together, and that is the point, isn’t it? –Test early, test often, test it again –Never compromise your ethics If the design isn’t working, is behind schedule or over budget, say so, don’t mislead anyone, they may be able to help If you see a problem, speak up Getting involved is the best way to learn –Space Grant provided opportunities I couldn’t get anywhere else Great exposure to industry Opportunities you don’t always get in industry –Learning in a classroom is one thing, but applying your skills in a “real world” environment with real accountability and responsibility is where the challenge and fun are.

Gateway to Space AJ - 17 Questions?