The proposed concept of communication satellite constellation such as Iridium (with 66 satellites) and Teledesic (with 840 satellites) in LEO has been studied for its operational constrains and the impact to the evolution of the future orbital debris environment. A large number of spacecraft in constellation creates a spike in spatial density distribution at a place where they are collocated in a thin shell, which in turn increases the collision probability with other space objects passing through the thin shell. Once a collision has occurred, most of the collision fragments and the damaged spacecraft will drift in the vicinity of the thin shell and further increase the mutual collision rate for the objects in the shell. This cascading effect is not only devastating to the operation of communication satellites in a constellation, but also has a significant impact on the evolution of the future orbital debris environment. Model calculations with a constellation of 1000 satellites at 600, 800, 1000 or 1500 km altitude are used to examine the fate of the satellites in the constellation and assess the impact on the orbital debris environment following the event. It is found that the optimal operational condition for these constellation satellites is to have a small cross-sectional area and for the constellation to be placed at an altitude region away from high concentrations of current space objects. (C) 1997 COSPAR.