IAC-10.A6.2.10 Effects of Space Debris on the Cost of Space Operations

1. IAC-10.A6.2.10Effects of Space Debris on the Cost of Space Operations William Ailor, The Aerospace Corporation James Womack, The Aerospace Corporation Glenn Peterson, The Aerospace Corporation Norman Lao, The Aerospace Corporation 61st International Astronautical Congress Prague, Czech Republic September 28, 2010

2. Overview • Background • Study Approach • Satellite Model • Constellations • Debris Model • Debris Effects on Satellite Lifetime • Debris Effects on Cost to Maintain Constellations

3. Today • Have about 1000 operating satellites • More than 20,000 tracked objects • Up to 600,000 pieces of debris large enough to cause loss of a satellite • Millions of smaller particles that can degrade performance

4. Possible Futures • No mitigation (no post-mission maneuvers to dispose of hardware) • 200 to 2000 km altitude orbits • 1997-2004 launch cycle • Predicts ~24 collisions in next 100 years • NASA study* shows removal of 5 large debris objects/year will stabilize population of orbiting objects in LEO • Discussions beginning on debris removal technique J.-C. Liou, “A statistical analysis of the future debris environment,” Acta Astronautica 62 (2008) 264 – 271. *J.-C. Liou and N.L. Johnson, “Active Debris Removal - The Next Step in LEO Debris Mitigation,” 26th IADC Meeting, 14-17 April 2008, Moscow, Russia. • PMD—Post-Mission Disposal actions • ADR—Active Debris Removal • Select objects with the highest [ mass  Pc ], where Pc is the instantaneous collision probability at the beginning of the year

5. Effects on Satellites and Satellite Operations • Higher costs of constellation maintenance • Replace degraded and destroyed satellites • Increased costs of satellites (robustness) • More collision avoidance maneuver actions (if service available) • Depends on quality of data • Increased threat during launch • Possible launch holds What will be the effect on cost?

6. Analysis Approach • Project populations of orbiting objects for 50 years • Define three generic satellites • Define critical areas for each satellite type and size of impacting object • 1 mm to 1 cm (untracked)—degrade solar panel performance • 1 cm to 10 cm (untracked)—degrade solar panel or kill satellite if strikes critical area • >10 cm (tracked objects)—strike anywhere kills satellite • Place satellites in “constellations” at worst-case altitude (850 km) • Assume constellations fully constituted in 2010, 2020, 2030 • Estimate changes in satellite lifetime due to debris environment • Estimate increased cost to maintain constellation at full strength for 20 years

7. Three Satellite Types & Sizes • Government satellite • Multiple missions • High reliability • High cost • Commercial #1 • Medium cost • Commercial #2 • Single mission • Low cost “factory built” Y direction X direction X direction Y direction Generic Government Satellite Z direction Z direction Generic Commercial Satellite

8. Debris Damage Assumptions solar arrays • Impacts on bus and payload {fatal only in critical areas} {fatal anywhere on bus and payload} {not fatal} 0 1 cm 10 cm Size of debris • Impacts on solar arrays critical areas 50% chance of no damage 40% chance knocks out 1 string 5% chance knocks out 2 strings 5% chance of fatal impact* 50% chance knocks out 2 strings 35% chance knocks out 3 strings 10% chance knocks out 4 strings 5% chance of fatal impact* No Damage 0 1 mm 1 cm 10 cm *This accounts for impact to harness, root connector, or yoke which would remove 25-100% of the array power and causes loss of mission

9. Constellations Government Commercial #1 Commercial #2

10. Location of Constellations • Satellites placed in region where flux of objects (and probability of collision) is highest • Sun-synchronous orbits at 850 km Location of constellations

11. Debris Size Ranges & Flux • Debris flux estimated using Aerospace model (>10 cm objects) and modified version of ESA’s MASTER05 (1 cm & 1 mm particles) • Includes man-made debris, micrometeoroids, operating satellites • Historical population up to 2005 • Model for 2010 and beyond adjusted for 2007 Chinese ASAT and 2009 Iridium/Cosmos debris • Added 2 to 3 debris producing events each decade • Collisions create debris clouds similar to Iridium-Cosmos collision • All satellites in highly inclined, sun synchronous orbits at ~850 km

12. Satellite Reliability Results 2-6% decrease 3-13% decrease

13. Constellation Replenishment Results 4-18% increase 2-8% increase

14. Replenishment Costs due to Debris Cost Assumptions Results 1-9% increase 3-18% increase 14

15. Summary • Results indicate slow cost increase due to debris environment at worst-case altitude • Small cost increase to operate in debris environment for next 30 to 50 years • Higher increase for commercial satellites due to lower solar panel margins; Increasing solar panel robustness reduces cost increase by ~50% • Collision avoidance service reduces cost increase by ~10%