With the Iridium constellation being operational now and several other Big-LEO constellations being under construction or at least under consideration, the space community is confronted with a completely new kind of commercial spaceflight. One of the major concerns in connection with the arrival of this new type of satellite services is its impact on the future evolution of the space debris population. The reason for these concerns lies within the huge number of space-craft being deployed into the most densely populated altitude regimes, since the probability for a fatal collision between two orbiting objects is clearly correlated with the spatial density. At IFR a new software tool named LUCA has been developed, which allows a semi-deterministic approach to the problem by simulating the launch, operation and post-mission disposal of the constellation members in detail. To eliminate stochastic effects in this procedure, several differently random-seeded program runs are combined. As a result, the evolution of the space debris population following different deploying scenarios (e.g. installation launches vs. sustaining launches, payload lethality) and mitigation strategies (e.g. re-orbiting vs. de-orbiting) can be predicted in great detail. In this paper, the impact of some exemplary constellation scenarious on the overall orbital debris situation during the next century is discussed. Especially, high-resolution plots of the spatial density evolution within the altitude regimes occupied by the constellations are presented.