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Overview

Overview. 3. 2. Introduction Design Analysis Fabrication Testing Conclusions. 4. 5. Introduction. V irginia T ech I onospheric S cintillation M easurement M ission (VTISMM) aka HokieSat I onospheric O bservation N anosatellite F ormation (ION-F) Utah State University

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Overview

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  1. Overview 3 2 • Introduction • Design • Analysis • Fabrication • Testing • Conclusions 4 5

  2. Introduction • Virginia Tech Ionospheric Scintillation Measurement Mission (VTISMM) aka HokieSat • Ionospheric Observation Nanosatellite Formation (ION-F) • Utah State University • University of Washington • Virginia Tech • University Nanosatellite Program • 2 stacks of 3 satellites • Sponsors: AFRL, AFOSR, DARPA, NASA GSFC, SDL University Nanosatellites AFRL Multi-Satellite Deployment System (MSDS) NASA Shuttle Hitchhiker Experiment Launch System (SHELS)

  3. Design Internal Configuration Crosslink Components Cameras Power Processing Unit Torque Coils (3) Magnetometer Camera Pulsed Plasma Thrusters (2) Camera Battery Enclosure Downlink Transmitter Electronics Enclosure Rate Gyros (3)

  4. Fabrication Composite structure comprised of 0.23” isogrid and 0.02” skin

  5. Static Testing Strength & stiffness test of structure without skin panels Strength & stiffness test of loading fixture

  6. Static Testing Strength & stiffness test of structure with skin panels • Experiment demonstrated a 32% gain in • stiffness in the cantilever mode due to addition of skins • Skins added less than 8% to the total mass

  7. Dynamic Testing Modal (tap) Testing of Side Panels • Hammer provides impulsive input • Accelerometer measures accelerations used to characterize natural frequencies • Tap testing with and without skins • Verification of predictions of finite element analysis

  8. Dynamic Testing Modal Testing of Side Panels (Without Skin) Mode 1 fn = 131 Hz (vs 131 Hz predicted) Mode 2 fn = 169 Hz (vs 171 Hz predicted)

  9. Dynamic Testing Modal Testing of Side Panels (With Skin) Mode 1 fn = 213 Hz (vs 131 Hz without skin) Mode 2 fn = 453 Hz (vs 169 Hz without skin)

  10. Dynamic Testing Modal Testing of Structure (Without Skins) Mode 2 fn = 272 Hz (vs 263 Hzpredicted) Mode 1 fn = 245 Hz (vs 249 Hz predicted)

  11. Dynamic Testing Z Y X Accelerometer Placement • X-axis control • Y-axis control • Z-axis control • Side panel 1 • Side panel 2 • Zenith panel • GPS (3 axis) • CPU (3 axis) • PPU (3 axis) • Battery box (3 axis) • Structure survived • all tests • Determined component locations to raise natural frequencies

  12. Conclusions • Aluminum isogrid increases structural performance at reduced mass • Modal testing verifies accuracy of isogrid side panel finite element model within ~1% error • Modal testing demonstrates 26% increase in structural stiffness of side panel by adding thin aluminum skins • Analyses and experiments verify structure satisfies all Shuttle payload requirements

  13. Acknowledgements • Air Force Research Laboratory • Air Force Office of Scientific Research • Defense Advanced Research Projects • Agency • NASA Goddard Space Flight Center • NASA Wallops Flight Facility Test Center • University of Washington • Utah State University • Virginia Tech • Professor A. Wicks • Professor B. Love • Members of ION-F

  14. Current Status • Structures: done except for safety • Thermal: refining model. Thermal cycling component testing early fall. • Power: boards prototyped. Bboxes fabbed. Proto pack assembled, waiting on thermal chamber for testing. • Comm: testing ground station hardware. Final flight antenna fab underway. • ADCS: everything fabbed and functionally tested. Writing code.

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