1. An Assessment of CubeSat Collision Risk H.G. Lewis 1, B.S. Schwarz 1, S.G. George 1 and H. Stokes 2 1 Astronautics Research Group, Faculty of Engineering & the Environment, University of Southampton, UK 2 PHS Space Ltd., UK IAC-14-A6.4.1

2. Volume 10×10×10 cm Mass < 1.33 kg Applications include: –Education –Remote sensing –Technology development “Most CubeSats fly at fairly low altitudes. They will not stay in orbit for decades. Furthermore, their trajectories can be controlled from launch, and they can be tracked fairly easily with radar. We know where they are, and where they are going. Fragmentation due to impacts with other objects is unlikely due to their small size.” Introduction & CubeSats

3. Historical CubeSat Launches

4. Historical CubeSat Conjunctions (1) Envisat

5. Historical CubeSat Conjunctions (2)

6. Historical CubeSat Conjunctions (3) Lifetimes > 25 years Lifetimes < 25 years

7. Based on predictions by SpaceWorks Enterprises Inc. Future CubeSat Launches

8. Initial population of objects ≥ 10 cm residing in or crossing the LEO region on 1 January 2013 30-year projection from 2013-2043 Future launch traffic based on launches from 2005-2012 –Without new CubeSat launches, or –With CubeSat launches corresponding to low, medium and high launch rates No explosions Spacecraft (except CubeSats) and rocket upper stages moved to decay orbits with lifetimes < 25 years at end-of- life (90% compliance) 100 Monte Carlo runs for each scenario DAMAGE Simulations

9. DAMAGE Results (1) 1-in-20 (SOCRATES)

10. DAMAGE Results (2)

11. DAMAGE Results (3) Medium launch rate

12. DAMAGE Results (4) Impactor mass > 500 kg Relative speed > 13.5 km/s

13. More than 360,000 conjunctions < 5 km involving CubeSats since November 2005 Millions of conjunctions predicted to occur in the next 30 years even for relatively low CubeSat launch rates –Many orbital regimes in LEO are affected –Most likely collision scenario is CubeSat and large object in Sun-synchronous orbit –Relatively few collisions (< 2) predicted Forecasted CubeSat activity is not sustainable without engagement with & leadership by “champions”, compliance with appropriate mitigation guidelines & understanding the shared “duty of care” for the environment Conclusions

14. Thank you for your attention Contact: hglewis@soton.ac.uk Financial support for this work was gratefully received from the Seventh Framework Programme (ACCORD Project 262824). Thanks to Holger Krag (ESA Space Debris Office) for permission to use the MASTER reference population, T.S. Kelso (CSSI) for assistance with the SOCRATES data, Craig Clark (Clyde Space Ltd.), Aleksander Lidtke (University of Southampton) and members of the IADC WG2 for valuable discussions.