340 C R E D IT : (T O P ) N A S A S ince the launch of Sputnik I, space activities have created an orbital debris environment that poses increasing impact risks to existing space systems, including human space flight and robotic missions (1, 2). Currently, more than 9000 Earth-orbiting man-made objects (including many breakup fragments), with a combined mass exceeding 5 million kg, are tracked by the U.S. Space Surveillance Network and maintained in the U.S. satellite catalog (3–5). Three accidental collisions between catalogued objects during the period from late 1991 to early 2005 have already been documented (6), although, fortunately, none resulted in the creation of large, trackable debris clouds. The most recent (January 2005) was between a 31-year-old U.S. rocket body and a fragment from the third stage of a Chinese CZ-4 launch vehicle that had exploded in March 2000. Several studies conducted during 1991–2001 demonstrated, with assumed future launch rates, the potential increase in the Earth satellite population, resulting from random, accidental collisions among resident space objects (7–13). In some low Earth orbit (LEO) altitude regimes, where the number density of objects is above a critical spatial density, the production rate of new debris due to collisions exceeds the loss of objects due to orbital decay. LEGEND (LEO-to-GEO Environment Debris model), is a highfidelity three-dimensional physical model developed by the U.S. National Aeronautics and Space Administration (NASA) that is capable of simulating the historical environment, as well as the evolution of future debris populations (14, 15). The LEGEND future projection adopts a Monte Carlo approach to simulate future onorbit explosions and collisions (16). A total of 50 (17), 200-year future projection Monte Carlo simulations were executed and evaluated, under the assumptions that no rocket bodies and spacecraft were launched after December 2004 and that no future disposal maneuvers were allowed for existing spacecraft (few of which currently have such a capability) (18). The simulated 10-cm and larger debris populations in LEO (defined as the region between altitudes of 200 and 2000 km) between 1957 and the end of a 200-year future projection period

https://science.sciencemag.org/content/sci/311/5759/340.full.pdf

Risks in Space from Orbiting Debris

An active debris removal parametric study for LEO environment remediation

Controlling the growth of future LEO debris populations with active debris removal

https://ntrs.nasa.gov/api/citations/20070013702/downloads/20070013702.pdf

A sensitivity study of the effectiveness of active debris removal in LEO

https://ntrs.nasa.gov/api/citations/20060024585/downloads/20060024585.pdf

D.T Hall

Papers

LEGEND - a three-dimensional LEO-to-GEO debris evolutionary model