Abstract: Space debris poses a dangerous threat to space activities. Ground-based laser is regarded as a feasible means to clean space debris. This paper analyzes the cleaning principle and constructes a model of orbital dynamics on debris removing. The effects are simulated by selecting two typical classes of lasers of ps and ns. Results show that neither of the two lasers could remove typical debris at the altitudes of 800 km and 1 500 km with one pass, and that multiple passes of the debris are required in order to achieve removing goals. A fraction of the mass of the debris must be ablated before it is captured by the atmosphere. The higher its altitude is, the more its ablated mass is needed. The ps class lasers has more advantages than the ns class. The total energy required for cleaning debris with ns class lasers of 15 kJ, 10 ns, 2 Hz is 2.95 times and 3.31 times that with the ps class of 150 J, 1 ps, 65 Hz at altitudes of 800 km and 1 500 km, respectively. This study can provide basic information for establishing debris removing schemes and selecting suitable laser parameters.

Key words: space debris, laser, laser ablation, impulse, ablation rate