1. Lower Baffle Robert Besuner 26 August 2004

2. 2Background/Purpose This study follows on to 12 August study of the Spacecraft Interface/Handling Ring. —In that study, the ring was assumed to be separate from lower baffle. —Main purpose of that study was to look at how the various components of the observatory might be supported on the ground. Discussions indicate it’s preferable to make the ring be integral with the lower baffle. —More structurally efficient. —Should not require much delta T or thermal isolation from spacecraft. General requirement for lower baffle design: —Should have removable access panels to allow ample access to lower optics bay. —Remaining structure should be spartan, but still able to handle expected ground loads. —Meet launch load requirements with access panels in place. —Closes out the aft end of the telescope (only vaguely addressed here).

3. 3 Lower Baffle, Closeouts in Place Aluminum assembly, except Ti thermal standoffs. Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections. Lower ring is 6mm thick by opening (purple). Columns are 100mm x 75 mm x 3mm box sections, with gussets. Closeouts are 1mm thick. 79.0kg total: 29.7kg lower ring 18.7kg upper ring 19.3kg columns 11.3kg closeouts

4. 4 Lower Baffle, Closeouts Removed Aluminum assembly, except Ti thermal standoffs. Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections. Lower ring is 6mm thick by opening (purple). Columns are 100mm x 75 mm x 3mm box sections, with gussets. Closeouts are 1mm thick. 79.0kg total: 29.7kg lower ring 18.7kg upper ring 19.3kg columns 11.3kg closeouts

5. 5 Lower Baffle, OTA Dummy Aluminum assembly, except Ti thermal standoffs. Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections. Lower ring is 6mm thick by opening (purple). Columns are 100mm x 75 mm x 3mm box sections, with gussets. Closeouts are 1mm thick. 79.0kg total: 29.7kg lower ring 18.7kg upper ring 19.3kg columns 11.3kg closeouts

6. 6 Lower Baffle, OTA, Upper Baffle Aluminum assembly, except Ti thermal standoffs. Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections. Lower ring is 6mm thick by opening (purple). Columns are 100mm x 75 mm x 3mm box sections, with gussets. Closeouts are 1mm thick. 79.0kg total: 29.7kg lower ring 18.7kg upper ring 19.3kg columns 11.3kg closeouts

7. 7 Lower Baffle, OTA, Upper Baffle, Radiator Aluminum assembly, except Ti thermal standoffs. Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections. Lower ring is 6mm thick by opening (purple). Columns are 100mm x 75 mm x 3mm box sections, with gussets. Closeouts are 1mm thick. 79.0kg total: 29.7kg lower ring 18.7kg upper ring 19.3kg columns 11.3kg closeouts

8. 8 Lower Baffle, OTA, Upper Baffle, Radiator Aluminum assembly, except Ti thermal standoffs. Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections. Lower ring is 6mm thick by opening (purple). Columns are 100mm x 75 mm x 3mm box sections, with gussets. Closeouts are 1mm thick. 79.0kg total: 29.7kg lower ring 18.7kg upper ring 19.3kg columns 11.3kg closeouts

9. 9 Lower Baffle Details 3mm thick columns/gussets 6mm thick angle 3mm thick angle 3mm thick gussets 8mm thick mounting/handling surfaces 1.5mm thick Ti thermal standoffs

10. 10 Deformation in 1g held by GSE (baffle displacement~2.6mm)

11. 11 Baffle/OTA Assembly Mode 1, 20Hz

12. 12 Baffle/OTA Assembly Mode 2, 23Hz

13. 13 Material Safety Factors

14. 14Conclusion Lower baffle assembly shown here is mechanically viable. Complete closing out of light needs to be addressed. Thermal performance should be confirmed.