Passive drag sail applications for the accelerated deorbit and targeted reentry of spacecraft
In the relatively short time that space has been an asset to humans, the amount of debris occupying the region has become a noticeable concern. Maintaining the usability of space for future generations requires consideration of novel methods to remove debris and otherwise prevent space from becoming further congested. One such proposed method is aerodynamic drag sails to accelerate the natural deorbit process caused by the high-altitude atmosphere. The method, properly implemented, could cause the spacecraft to reenter the atmosphere and burn up without requiring the planning of additional maneuvers, potentially saving time and money while still meeting international requirements. Analysis of the technique requires solving the expected times in orbit and selecting a sail that optimizes cost relative to the spacecraft's orbital lifetime, initially using CubeSats. Atmospheric drag, however, is only one of many forces that may perturb a spacecraft along its trajectory. Solar radiation pressure is another source of perturbing forces acting on large surfaces in the direction of the Sun. After including these forces in high-fidelity deorbit analysis, one can predict where the spacecraft would likely impact the Earth if components do not burn up in Earth's atmosphere. To prioritize the safety of life and property on the surface, legal requirements dictate the location where the spacecraft may impact the surface. Since a passive drag sail does not have active control authority, the sail's initial deployment timing, orientation, and altitude dictate the final reentry point for a given gravitational and atmospheric drag model. Based on specific initial conditions, it is possible to show that a drag sail is an effective and efficient method of safely deorbiting a spacecraft while optimizing cost and conforming to legal requirements.