point that ASOs are not distributed at random, but clustered into orbital shells or highways. Below the size of the tracked objects, the global community hypothesises many untrackable ASOs, possibly as many as 130 million in total. In orbit, typical relative velocities are so high (~10-15 km/s) that even small pieces of debris can cause considerable damage if they collide with something else in orbit (i.e. bullets are small but cause significant damage due to their kinetic energy), and create a growing risk for satellites.
Fig. 2 Visualisation of the currently tracked objects in Low Earth Orbit. Height is the average of apogee and perigee, relative to a mean Earth radius of 6,378 km. Blue dots are active satellites; red dots are "left overs" such as derelict satellites, rocket bodies and other large parts; grey dots are other debris, down to a scale of approximately 10 cm. Black dots are simulated debris from the recent destruction of Kosmos 1408 by a Russian weapon test, simulated by H.G. Lewis (private communication). The other data points are from the General Catalog of Artificial Space Objects [5]. In the upper plot, the y-axis is simply a random number between 0 and 1, to stretch the points out in two dimensions for clarity. It could be thought of as an artificial azimuth.
