1. © The Aerospace Corporation 2010 IAC-10.A6.2.10 Effects 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 61 st 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 2

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 3

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 PMDPost-Mission Disposal actions ADRActive Debris Removal Select objects with the highest [ mass P c ], where P c is the instantaneous collision probability at the beginning of the year *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. 4 J.-C. Liou, A statistical analysis of the future debris environment, Acta Astronautica 62 (2008) 264 – 271.

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? 5

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 6

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 X direction Z direction Y direction X direction Z direction Y direction Generic Government Satellite Generic Commercial Satellite 7

8. Impacts on bus and payload 1 cm010 cm {not fatal} {fatal only in critical areas} {fatal anywhere on bus and payload} Size of debris Impacts on solar arrays No Damage 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* 1 mm01 cm10 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 critical areas solar arrays Debris Damage Assumptions 8

9. Constellations Constellation No. of Satellites in Constellation Satellite Design Life (Years) Satellite Unit Cost ($M) Launch Cost ($M) Notes Government56750250Heavy lift ELV Commercial #120925080Medium lift ELV Commercial #270125080 Medium lift ELV, 5 satellites co-manifested per launch Government Commercial #1Commercial #2 9

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 10

11. Debris Size Ranges & Flux Debris flux estimated using Aerospace model (>10 cm objects) and modified version of ESAs 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 11

12. Satellite Reliability Results Satellite Type Mean Lifetime (No Debris) Mean Lifetime & Percent Reduction (With Fatal Impacts Only) Mean Lifetime & Percent Reduction (All Impacts) Launch Year2010204020102040 Government 5.67 years 5.55 years 2.1% 5.54 years 2.3% 5.48 years 3.4% 5.42 years 4.4% Commercial #1 8.97 years 8.56 years 4.6% 8.52 years 5.0% 8.29 years 7.6 8.17 years 8.9% Commercial #2 12.26 years 11.63 years 5.1% 11.56 years 5.7% 11.24 years 8.3% 10.65years 13.1% 2-6% decrease3-13% decrease 12

13. Constellation Replenishment Results Constellation Year Constellation Constituted Number of Replenishment Launches (No Debris) Number of Replenishment Launches (With Fatal Impacts Only) Number of Replenishment Launches (All Impacts) Government 2010 2020 2030 20.1 20.4 (2% Increase) 20.5 (2% Increase) 20.8 (4% Increase) 20.9 (4% Increase) Commercial #1 2010 2020 2030 51.4 53.7 (5% Increase) 53.8 (5% Increase) 54.1 (5% Increase) 55.9 (9% Increase) 56.2 (9% Increase) Commercial #2 (5 sats/launch) 2010 2020 2030 24.1 25.9 (7% Increase) 26.0 (8% Increase) 27.5 (14% Increase) 28.0 (16% Increase) 28.5 (18% Increase) 2-8% increase 4-18% increase 13

14. Replenishment Costs due to Debris Cost Assumptions Results Constellation Satellite Unit Cost ($M) Launch Cost ($M) Notes Government750250Heavy lift ELV Commercial #125080Medium lift ELV Commercial #25080 Medium lift ELV, 5 satellites co- manifested per launch Constellation Year Constellation Constituted Replenishment Cost ($B) No debrisFatal onlyAll impacts Government 2010 2020 2030 20.1 20.4 (1% increase) 20.5 (2% increase) 20.8 (3% increase) 20.9 (3% increase) Commercial #1 2010 2020 2030 17.0 17.7 (5% increase) 17.8 (5% increase) 17.9 (5% increase) 18.4 (9% increase) 18.5 (9% increase) Commercial #2 2010 2020 2030 7.9 8.5 (8% increase) 8.6 (9% increase) 9.1 (14% increase) 9.2 (16% increase) 9.4 (18% increase) 1-9% increase3-18% 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% 15