1. General information on orbital debris can be found in NASA Orbital Debris quarterly news, 〈http://orbitaldebris.jsc.nasa.gov/newsletter/newsletter.html〉.
2. Space track 〈http://www.space-track.org〉.
3. D. McKissock, JSpOC conjunction assessment process, in: Proceedings of the 1st International Conjunction Assessment Workshop, CNES, Paris, 19–20 May 2015.
4. M. Moury, CAESAR-conjunction assessment with Middle Man, in: Proceedings of the 1st International Conjunction Assessment Workshop, CNES, Paris, 19–20 May 2015.
5. Collisional cascading: the limits of population growth in low Earth orbit;Kessler;Adv. Space Res.,1991