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- 1. On problems of active space debris removal using tethered towing Vladimir S. Aslanov and Vadim V. Yudintsev Samara State Aerospace University (SSAU), Russia 6th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 2. Satellites with flexible appendages and/or fuel residuals Upper stages with fuel residuals Large Space Debris: 26th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 3. Tug-Tether-Debris system 36th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 4. • Analysis of the pre-capture motion of the debris • Pre-burn stabilization of the debris • Post-burn dynamics and stabilization taking into account properties of the debris (flexible appendages, fuel) • Post burn dynamics & motion of the center of mass • Atmospheric re-entry of the debris Problems need to be considered 46th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland) Solved Not yet solved
- 5. Re-enter into atmosphere Deorbit Catch & Stabilization Uncontrolled motion Operational stage Active Stage / Separation Stages 56th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland) Initial conditions for the upper stage type debris uncontrolled motion Initial conditions for the re-entry Initial conditions for the catch stage This stage determine safety of the ADR
- 6. The attitude motion of the upper stage (debris) can be predicted using the models of the perturbing forces of: • separation system • the Earth gravity&magnetic fields • the atmosphere • the Moon, the Sun etc. The motion of the upper stage 66th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 7. The motion of the non-operating satellite 76th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland) The attitude motion of the satellite (debris) can be predicted using the models of the perturbing forces and last telemetry data.
- 8. • Equations for the osculating orbital elements • Equations in non-inertial orbital frame • Flexible appendages: floating frame of reference formulation • Sloshing dynamics: pendulum equivalent models Mathematical model structure 86th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland) 1. Equations of the mass center 2. Equations of the attitude motion of the system 3. Equations for additional elements (fuel, flexible appendages)
- 9. Forces and Torques 9 • Tug’s thrust • Tether tension (depend on Young's modulus, cross section area, damping) • Aerodynamic forces • Gravitational forces and torques • Magnetic forces and torques • Sunlight pressure • Control forces and torques 6th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 10. • Debris • Flexible appendages • Fuel • Tether • Stiffness • Damping • Tug • Tether control Complex model of the tug-debris system 106th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 11. • Figure shows oscillations of the angles α between the tether and the axis Oyo of the orbital rotating frame with undesirably high amplitudes while θ is small. • Marked oscillations caused by the gravitational torque that is created by the difference between the gravity forces act on the space tug and on the orbital debris. Example: the influence of gravitational torque 116th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 12. Stationary point as a function of tether length 126th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland) F=0,3 N safe
- 13. Example: closely spaced frequencies 136th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland) • The amplitude of the tether vibrations is influenced by the vibrations of the solar panels and and vice versa. • At t=15 the deformation of the panel 2 reach the breaking strain (dotted red lines) causing structure failure.
- 14. Debris with fuel residuals 146th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland) • Sloshing liquid is modelled as an equivalent pendulum. • The oscillations of liquid are small
- 15. Example: Nonlinear vs. linearized formulation 156th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 16. We have developed the mathematical model of the attitude motion of the debris+tether+tug system: • Tug + Elastic Tether + Debris with flexible appendages • Tug + Elastic Tether + Debris with fuel residuals Conclusion 166th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 17. • Capture dynamics of debris (harpoon, net, lasso ...) • The stabilization phase after debris capture What we will intend to do? 176th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland) We will study: We will create comprehensive model for all stages: from the capture to re-entry
- 18. Rigid body debris [1] V.S. Aslanov, V. V. Yudintsev, Dynamics of Large Debris Connected to Space Tug by a Tether, J. Guid. Control. Dyn. 36, 2013. P. 1654–1660. [2] V. Aslanov, V. Yudintsev, Dynamics of large space debris removal using tethered space tug, Acta Astronaut. Volume 91, 2013, P. 149-156. Debris with flexible appendages [3] V. S. Aslanov, V. V. Yudintsev, Behaviour of Tethered Debris With Flexible Appendages Acta Astronaut. 104, Issue 1, 2014. P. 91-98. [4] V. S. Aslanov and V. V. Yudintsev Dynamics, Analytical Solutions and Choice of Parameters for Towed Space Debris with Flexible Appendages. Adv. Sp. Res. Volume 55, Issue 2, 2015. P. 660-667. Debris with fuel residuals [5] V. S. Aslanov and V. V. Yudintsev The motion of tethered tug-debris system with fuel residuals. Adv. Sp. Res. (Accepted for publication). Re-entry [6] V. Aslanov, A. Ledkov, Dynamics of towed large space debris taking into account atmospheric disturbance, Acta Mech. Volume 225, Issue 9, 2014. P. 1-13. Publications 186th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 19. Thank You for attention 196th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)
- 20. • Vladimir S. Aslanov Prof., Head of the Theoretical Mechanics Department, Samara State Aerospace University aslanov_vs@mail.ru http://aslanov.ssau.ru • Vadim V. Yudintsev Associate Prof., Theoretical Mechanics Department, Samara State Aerospace University yudintsev@classmech.ru http://yudintsev.info Authors 206th EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (29 June – 3 July 2015, Kraków, Poland)