1. Spacecraft Interface/Handling Ring Robert Besuner 12 August 2004

2. 2 Purpose of the Ring Base to which to mount the telescope and outer baffle. Interfaces ‘instrument’ to spacecraft (and divides instrument from spacecraft). Provides attach points for a handling fixture (to handle any combination of spacecraft, telescope, and outer baffle). Provides a place to attach thermal isolator mounts. —Want to thermally isolate entire instrument from spacecraft. —Want to thermally isolate telescope struts from baffle. Could possibly serve as the lower frame of the baffle.

3. 3Ring

4. 4 Ring, Telescope Dummy

5. 5 Ring, Telescope Dummy, Baffle Dummy

6. 6 Ring, Telescope Dummy, Baffle Dummy, Spacecraft Dummy Telescope dummy mass = 500kg. Baffle dummy mass = 260kg. Spacecraft dummy mass = 750kg. Ring mass = 25.3kg.

7. 7 Ring, Telescope Dummy

8. 8 1.5mm thick x 50mm dia Ti thml standoff (telescope mounts aligned with telescope support) 4mm thick flanges in reinforced areas 2.5mm thick cross-ribs and tab gussets 8mm thick mounting tab 8mm thick web in reinforced areas 3mm thick web and flanges on nominal 100mm x 100mm ‘H’ section Aluminum ring mass = 25.3 kg

9. 9 Ring, Telescope Dummy

10. 10 Ring, Telescope Dummy 1.5mm thick x 50mm dia Ti thml standoff (telescope mounts aligned with telescope support). Each 50mm tall element is 0.032 watt/C. Or 0.095 watt/C total between SC and telescope or between SC and baffle. 4mm thick flanges in reinforced areas 2.5mm thick cross-ribs and tab gussets 8mm thick mounting tab 8mm thick web in reinforced areas 3mm thick web and flanges on nominal 100mm x 100mm ‘H’ section Aluminum ring mass = 25.3 kg Fastening and access issues need more detailed examination. Mounting node (pin joint—conservative)

11. 11 Are Mounts Stiff Enough for Flight? Modal analysis on model shown, fixed at bases of thermal mounts: —With 1.5mm thick mounts, frequencies are 55, 55, 112 Hz. —With 3.0mm thick mounts, frequencies are 60, 60, 122 Hz. Omitting ring, and fixing bases of telescope struts frequencies are 70, 70, 141 Hz. (Ignored baffle for this analysis because its modes are lower than these and the mass dummy model is too simplified.)

12. 12 Are Mounts Strong Enough For Flight? Bases of (1.5mm thick) thermal mounts fixed, applied launch load accelerations (2g lateral, 6.5 g axial). Ti thermal mounts and aluminum ring safety factors are all 20+.

13. 13 Are Mounts and Ring Strong Enough For Handling? Support load vertically or horizontally in one g using ring mounting ears. Various load combinations. Desire material yield safety factor of 4 or greater.

14. 14 Alternative configuration consideration It might be efficient and convenient to make the ring serve as the base of the lower baffle. —Pro: Ring is in the right place to be the lower frame of the baffle. The lower baffle likely has removable access panels, meaning it will likely want a fairly rigid base. Lower part count, probably less mass. —Con: Ring would be integral to the baffle, making them (inconveniently) inseparable. The (cold) baffle would be thermally coupled something like four times as well to the spacecraft and something greater than twice as well to the telescope struts.

15. 15Conclusion A feasible interface/handling ring design is presented. Thermal analysis should be done to verify thermal mounts presented here are adequate. Packaging, assembly and many other considerations need to be examined.