1. DINO PDR 24 February 2016 Colorado Space Grant Consortium1 Gravity Gradient Tether Deployment Requirements –11 lb (5 kg) tip-mass must be deployed 65 ft (20 m) –Tip-mass must stay within 60º from zenith to retain gravity gradient stability –Tip off rate should be less than 3 °/s Assumptions –ADCS will de-tumble satellite and make tip-mass zenith pointing Pitch: ±15º from zenith, ω < 0.1 °/s Roll: ±5° from zenith, ω < 0.25 °/s Yaw: no pointing requirement, ω <.5 °/s

2. DINO PDR 24 February 2016 Colorado Space Grant Consortium2 Deployment Method Open-Loop Deployment –Lightband will provide kickoff velocity of 2 ft/s Deployment will take about 40 sec –Tether will be “left-behind” by tip mass –Coulomb Damper will provide braking for end of travel Braking System Tether Z-fold Tip MassMain Satellite Lightband Tether Guides Velocity

3. DINO PDR 24 February 2016 Colorado Space Grant Consortium3 Tether Low-density polyethylene tape –Along length are three strands of 0.003 inch thick Spectra® 1000 Used for rip-stop protection, not load- bearing 0.005 inch by 1 inch cross-section Linear Density = 0.002173 kg/m Young’s Modulus = 3.069 x 10 10 N/m 2 Flown on Advanced Tether Experiment (ATEx) mission Tether Material

4. DINO PDR 24 February 2016 Colorado Space Grant Consortium4 Lightband 15 inch motorized separation system Delta V = 2 ft/s m ≈ 6.5 lbm Tip-off rate < 1º/s Flight proven –Deployed Starshine-3 satellite from Athena launch vehicle in 2001

5. DINO PDR 24 February 2016 Colorado Space Grant Consortium5 Braking System Uses friction to dissipate deployment energy Brakes tip-mass in last 3 ft. of deployment Materials –Wheel – Anodized Al –Brake Shoe – Delrin AF E diss = 8.22 in-lb –F f =.2284 lb Brake shoe Tether Wheel

6. DINO PDR 24 February 2016 Colorado Space Grant Consortium6 Failure Contingencies Tether catching/snaging –Tether expected to twist after deployment –DOF of tether z-fold limited –Room provided between guides Imperfect energy dissipation Tip-off/stiction Recoil

7. DINO PDR 24 February 2016 Colorado Space Grant Consortium7 Appendix A – Drag-along vs. Leave Behind