1. Long-term evolution of the space debris population Dr Hugh Lewis Astronautics Research Group, Faculty of Engineering & the Environment

2. Space debris 101…

3. Space debris sources

4. Space debris population (1) Data courtesy of NASA Orbital Debris Program Office

5. Space debris population (2) Softball size or larger (  10 cm) ~22,000~500,000~100,000,000 Total mass: ~6,500 tonnes (> 2,700 tonnes in LEO) Marble size or larger (  1 cm) Ball-point pen tip (  1 mm)

6. ≥ 10 cm debris population ESA MASTER 2009 population seen in DAMAGE ~30,000 objects ≥ 10 cm May 2009

7. View from the ISS Simulated view from the ISS, with orbiting objects from space-track ≥ 10 cm debris population

8. UN space debris mitigation guidelines 1.Limit debris released during normal operations 2.Minimize the potential for break-ups during operational phases 3.Limit the probability of accidental collision in orbit 4.Avoid intentional destruction and other harmful activities 5.Minimize potential for post-mission break-ups resulting from stored energy 6.Limit the long-term presence of spacecraft and launch vehicle orbital stages in the low Earth orbit (LEO) region after the end of their mission 7.Limit the long-term interference of spacecraft and launch vehicle orbital stages with the geosynchronous (GEO) region after the end of their mission

9. Remediation Even with good compliance with the commonly adopted mitigation guidelines, the space debris population is likely to grow: –Active Debris Removal About 50 removals needed to prevent one collision $1 – $3 billion per year

10. LEO mitigation & remediation 30% compliance 90% compliance 90% compliance with 5 removals per year

11. LEO mitigation & remediation 90% compliance 90% compliance with 5 removals per year Chance of the same result 1-in-501-in-2001-in-5

12. 12 Summary Compliance with debris mitigation guidelines is currently low –Even if compliance rates improve the debris population is likely to continue to grow: Catastrophic collisions every five to ten years Impact on spacecraft operations Remediation of the debris environment –Can help to limit the growth of the debris population: Activity needs to be sustained (expensive!) Catastrophic collisions will still occur Success is uncertain Challenges: –Compliance, Consensus, Cooperation, Collaboration, Contributions

13. Thank you for your attention Contact: hglewis@soton.ac.uk Thanks to Holger Krag (ESA Space Debris Office) for permission to use the MASTER reference population, and J.-C. Liou (NASA Orbital Debris Program Office) for permission to use the satellite catalogue data