Laser ablation based on-orbit debris removal

Abstract

Space debris are defunct man-made satellites orbiting in the low-earth orbit (LEO) and Geo-synchronous orbit (GEO) orbiting around earth with high velocities posing a serious threat for current and future missions. Controlling the growth of debris is of great importance for sustained space operations. This has led researchers to investigate a wide variety of active debris removal missions basing on their characteristics: contact less, contact, capturing and drag augmentation methods. This thesis discusses space debris removal using ground based lasers. The effect of laser ablation on de-orbiting process was investigated using Sims-Flanagan model, where change in momentum translates in gradual change in the debris trajectory. A 5 cm spherical shaped debris of mass 0.1 kg was modeled using a series of change in velocities ( Δv's) due to multiple laser engagements to achieve the target orbit of 120 km altitude. The translational dynamics of the debris was determined assuming laser propagation vector non-tangential to its surface under the influence of atmospheric drag. It was observed that the total de-orbit time decreases with the increase in laser coupling coefficient and decrease in laser pulse duration. The model estimated hours to reach the target perigee radius with laser engagement of each 30 seconds, for the coupling coefficient of 6 units, and the correspondingly seconds and engagements for the 6ns laser pulse duration. The model also observed that the atmospheric drag influenced the de-orbit time exponentially accelerating the process as it approaching the earth atmosphere.