1. ARISSat-1 Critical Design Review Orlando, Feb 15, 2010 Mechanical Bob Davis, KF4KSS@amsat.orgKF4KSS@amsat.org

2. Feb 15, 2010ARISSat-1 CDR2 Introduction Mechanical subsystem includes structure and electronics boxes. Scope –Requirements –Design –Safety Considerations –Verification –Operations –Status

3. Feb 15, 2010ARISSat-1 CDR3 Requirements Simple structure that can be implemented quickly Provide attachment for: –SMEX solar panels –electronics boxes (IHU, Rx/Tx, MPPT, Control Panel) –Orlan-M battery (integration on ISS) –Kursk experiment (integration in Russia) –Spare experiment box –4 cameras –2 whip antennas –Handles Survive Progress loads (“CargoTransReqP103.doc”) Low outgassing Venting of volumes

4. Feb 15, 2010ARISSat-1 CDR4 Path to Structure Prior to July 2009, SuitSat-2 used a Russian spacesuit

5. Feb 15, 2010ARISSat-1 CDR5 Foamboard Mockups August 2009September 2009

6. Feb 15, 2010ARISSat-1 CDR6 Exploded View Russian battery IHU MPPT Rx/Tx September 2009

7. Feb 15, 2010ARISSat-1 CDR7 Solar Panel Views October 2009

8. Feb 15, 2010ARISSat-1 CDR8 Interior and Cover Views

9. Feb 15, 2010ARISSat-1 CDR9 Design Methodology For conservative structure, we want low stresses, small deflections, and high frequencies (or at least >>50 Hz) All “masses” are attached to the Top & Bottom Plates, which are ¼” thick aluminum –Thick enough for helical thread inserts –Much faster to process than honeycomb sandwich panels –Easy to over-design (which also lessens analysis burden) –Given schedule, the above advantages outweigh the mass penalty The Plates are separated by custom machined angles in the four corners, also ½” thick Side Panels (with SMEX Solar Panels) act only as shear planes Small angle extrusion joins edges of Side Panels to Top & Bottom Plates Added flanges to die cast aluminum electronics boxes

10. Feb 15, 2010ARISSat-1 CDR10 Sample: Top Plate

11. Feb 15, 2010ARISSat-1 CDR11 Sample: IHU Box

12. Feb 15, 2010ARISSat-1 CDR12 Sample: Cover Ass’y (Back when it was Aluminum not Lexan)

13. Feb 15, 2010ARISSat-1 CDR13 Camera Mirror Unsuccessful search to find first- surface VDA mirror on any Lexan (by name brand) Several options for first-surface VDA mirror on unknown polycarbonate (no paperwork) Starting search for VDA mirror on aluminum –“grainy” finish will result in degraded image quality Can we find contact for the astronaut spacesuit “sleeve-mounted mirrors”? Considering simpler triangular brackets with pockets for bonding opposite edges of the mirror –Mirror is then positively captured –Bracket dims independent of mirror thickness (because we shim pocket) Monolithic mirror bracket concept

14. Feb 15, 2010ARISSat-1 CDR14 Side Camera Angle Dimensions of mirror are very sensitive to angles (FoV & mirror) Image requires mirror at least 1.5” wide x 1.75” long (57° from horizontal) Verified screw heads and mirror bracket are not in FoV

15. Feb 15, 2010ARISSat-1 CDR15 Safety Considerations All external edges/corners are rounded All materials are low outgassing Handles sized for gloves

16. Feb 15, 2010ARISSat-1 CDR16 Analysis Methods No Finite Element Model (FEM) or Analysis (FEA); just hand calcs Plate natural frequency per, Vibration Analysis for Electronics Equipment 3 rd Edition by Steinberg 2000, and per Dynamic Analysis and Failure Modes of Simple Structures by Schiff, 1990 Honeycomb per above and Spacecraft Structures and Mechanisms edited by Sarafin And Larson, 1995 Vertical Angle combined loading per Spacecraft Structures and Mechanisms by Sarafin & Larson, 1995 Fastener combined loading per Analysis and Design of Flight Vehicle Structures by Bruhn 1973 and per NASA Technical Memorandum 106943 Preloaded Joint Analysis Methodology for Space Flight Systems Vented volumes in depressurization per AIAA-87-1598 Payload Venting in Worst Case Shuttle Environments General References –MIL-HDBK-5J Metallic Materials and Elements for Aerospace Vehicle Structures –Roark’s Formulas for Stress and Strain 7 th Edition by Young & Budynas, 2002 –Space Mission Analysis and Design, 3 rd Edition by Wertz & Larson, 1999 –FEMCI Book, http://femci.gsfc.nasa.gov/femcibook.html

17. Feb 15, 2010ARISSat-1 CDR17 Margins Summary Simultaneous 10g vertical and 6g horizontal Material Factors of Safety –Yield, FSy = 1.2 –Ultimate, FSu = 1.5 Threaded fastener Factor of Safety –FS = 2.0 All margins are large Partial summary table below

18. Feb 15, 2010ARISSat-1 CDR18 Sample: Top Plate Frequency

19. Feb 15, 2010ARISSat-1 CDR19 Sample: Top Plate Screws

20. Feb 15, 2010ARISSat-1 CDR20 Sample: IHU Box

21. Feb 15, 2010ARISSat-1 CDR21 Vented Volumes Structure and all electronics boxes have vent holes Gap between Solar Panels & Covers can vent via small harness holes in SMEX, and “through” perimeter Velcro Used at least twice the vent hole cross-sectional area suggested by AIAA-87-1598 Payload Venting in Worst Case Shuttle Environments –Rule of thumb: 0.050” in 2 unrounded hole for each 1.0 ft 3 generates 0.5 psi pressure (box bloating) during ascent Always sought redundant holes in the event paint, tape, or potting caused a plugging event

22. Feb 15, 2010ARISSat-1 CDR22 Verification Structure was prototyped –Changed Camera mount, some longer free-running Helicoils Observatory level vibration testing –Expected @ GSFC Kursk experiment mass mockup No Orlan-M battery (not installed for launch either) –Levels TBD from “CargoTransReqP103.doc”, Requirements for International Partner Cargo Transported on Russian Progress and Soyuz Vehicles, П32928-103 (discussed later)

23. Feb 15, 2010ARISSat-1 CDR23 Drawing Status Structure - 15 Solar Panels & Covers - 6 Electronics Boxes - 18 Cameras - 3 Tabletop Stand - 0 Shipping Container - 0 Vibration Adapter - 0 Thermal Vacuum Adapter - 0

24. Feb 15, 2010ARISSat-1 CDR24 Fabrication Status Structure – in plating Solar Panels & Covers – bonding & Lexan change Electronics Boxes – painted & taped Cameras – waiting for brackets drawing Tabletop Stand - sketch Shipping Container – purchased; mod? Vibration Adapter – pending facilities Thermal Vacuum Adapter – pending facilities