Space Debris Environment Impact Rating System

1. Space Debris Environment Impact Rating System H.G. Lewis1, S.G. George1, B.S. Schwarz1 & P.H. Stokes2 1 University of Southampton 2 PHS Space Ltd.

2. Introduction: ACCORD Alignment of Capability and Capacityfor the Objective of Reducing Debris • FP7-funded project: University of Southampton & PHS Space Ltd. • Aims: • Provide a mechanism for communicating the efficacy of current debris mitigation practices • Identify opportunities for strengthening European capability • Activities: • Surveying the capability of industry to implement debris mitigation measures • Reviewing the capacity of mitigation measures to reduce debris creation • Combining capability and capacity indicators within anenvironment impact rating system

3. Environment Impact Rating System • Tool to evaluate how spacecraft design & operation impacts the long-term debris environment • Communicate how mitigation measures and good design practices can improve environmental impact • Based on a single score: • Combines measures of compliance, capacity and capability of various mitigation techniques • Incorporates current state of debris environment • Final system will be available online as voluntary (and confidential) tool for industry • A prototype rating system for the LEO environment is presented here

4. Environment Impact Rating System Two aspects: • Space “Health” Index • Provides context and calibration forenvironmental impact rating • Score out of 100 • Environmental Impact Rating • Measure effect of future spacecraft on debrisenvironment • Input data provided by manufacturer/operator • Score out of 100 1. “Health” Index User InputsSPACECRAFT DATA, APPLIED MITIGATION MEASURES Calibration Environmental Impact Rating 2.

5. 1. Space “Health” Index “Health” ~Assess the “health” of the space environment with respect to 2 goals: • Widespread Implementation of Mitigation Measures • Protection of Service • Legacy of Service • Benign Space Debris Environment For each goal, the index calculates a score (out of 100), which is a measure of how well the goal has been realised A measure of the long-term sustainability of outer space activities Leads to a measure of a “healthy” space environment to be used in the impact rating calculation

6. 1. Space “Health” Index Measured Value ReferencePoint Outside influences affect achievement of goal: • ‘Pressures’ cause deviation away from goal • ‘Resiliences’ direct status towards goal For each goal, the index calculates: • ‘Present’ statusmeasured value, relative to a defined reference point • Predicted ‘Near-Future’ statusestimated using trend of status over previous 5 years, pressures and resiliences Present Status Goal 5 YearTrend Near-Future Likely Status Resiliences Pressures Technique adapted from Ocean Health Index Halpern et al. (2012, Nature)

7. 1. Space “Health” Index • Focus, to-date, on LEO: divided into 35 regions: • 7 altitude bands (categorised by perigee) • 5 inclination bands: • Equatorial (0º-19º) • Intermediate (20º-84º) • Polar (85º-94º) • Sun-Synchronous (95º-103º) • Retrograde (104º-180º) • “Health” score derived for each goal in each region (deg) Combined to give overall “health” of LEO

8. Goal 1A: Protection of Service Compliance with mitigation guidelines & good practicesthat are implemented to avoid loss during operations • Impact shielding, collision avoidance • Reference: • 100% compliance for all measures by all spacecraft in region • Pressures: • Technicaland financial challenges • Resiliences: • Availability of data, tools, techniques and supporting guidelines • Source of Data: • ACCORD industry survey, ACCORD compliance analysis

9. Goal 1B: Legacy of Service Compliance with mitigation guidelines & good practices that are implemented to preserve the space environment • Post-mission disposal, passivation, limiting release of MRO • Reference: • 100% compliance for all measures by all spacecraft in region • Pressures: • Technical and financial challenges • Resiliences: • Availability of data, tools, techniques and supporting guidelines • Source of Data: • ACCORD industry survey, ACCORD compliance analysis

10. Goal 2: Benign Space Debris Environment Current state of the debris environment and future trends: • Number of ≥ 10 cm debris objects • Reference: • Population of objects ≥ 10 cm on 1st May 2009 • Population of objects ≥ 10 cm on 1st May 2014 (no collisions scenario) • Pressures: • Technical and financial challenges of implementing mitigation measures • Resiliences: • The requirement to comply with mitigation guidelines and standards • Source of Data: • MASTER 2009 population and DAMAGE future projection

11. Data Sources DAMAGE Simulations: • Capacityof mitigation measures to limit creation of further debris • 16 Mitigation scenarios (PMD, PASS, MRO, CA; plus combinations) • Effectiveness of mitigation measure normalised between 0 (no mitigation) and 1 (full mitigation) in terms of no. objects & no. catastrophic collisions ACCORD Industry Survey • Technical and financial challenge of implementing mitigation measures (Capability) • Survey responses normalised to give score between 0 and 1 • Level of implementation of mitigation measures among spacecraft manufacturers and operators • Survey responses normalised to give score between 0 and 1

12. Data Sources http:// www.fp7-accord.eu

13. 2. Environmental Impact Rating Quantify impact of a prospective spacecraft on the space environment User-Specified Inputs(for prospective spacecraft): • On-Orbit Mass • Perigee Altitude • Orbital Inclination • Mitigation MeasuresImplemented • How Individual Measuresare Implemented in Design Lead to: 3 parameters, which combine to give single score for spacecraft (out of 100) How Mitigation Measures are Implemented UserInputs Orbit DataAltitudeInclination Mitigation Measures Used Defines LEO Region Rating Calculation

14. 2. Environmental Impact Rating Rating Parameters: • Debris score for the prescribedorbital region(how “crowded” the region is) • The capacity of appliedmitigation measures to limit the generation of new debris (from DAMAGE) • How the prospective spacecraftaffects the “health” index in thegiven orbital region (re-calculate “health” index) How Mitigation Measures are Implemented UserInputs Orbit DataAltitudeInclination Mitigation Measures Used “Health”Index Defines LEO Region Modification to “Health” Index for LEO Region Capacity of Mitigation to Limit Future Debris Crowding of Debris in LEO Region Environmental Impact Rating All scores expressed out of 100

15. Representative ‘Certificate’ Example:Generic Earth Observation Spacecraft • Inputs: • Mass: 1000kg • Altitude: 795km • Inclination: 98 • Applied Mitigation Measures: • Collision Avoidance • Passivation • Limiting MRO Release Impact Rating: 23 %Change in “health” of region:Change in “health” of LEO:Suggested ‘actions’ to improve rating +0.16 %+0.01%

16. Conclusions and Future Work • A prototype Environmental Impact Rating System for space systems has been developed comprising two aspects: • Space “Health” Index • Environmental Impact Rating • Based on data gathered from industry and other sources, in addition to simulations performed using DAMAGE • Future work: • Improve the assumptions made in the prototype • Community and industry engagement is anticipated (and welcomed) to address these assumptions and ensure the applicability of the finished system • Final system will be implemented in a web-tool and hosted client-side to ensure privacy

17. Funding provided by the European Union Framework 7 Programme (Project No. 262824). Thanks to Carsten Wiedemann (TU Braunschweig), Adam White (University of Southampton), Richard Tremayne-Smith, and HolgerKrag (ESA Space Debris Office) Contact: http:// www.fp7-accord.eu Dr. Hugh G. Lewis Astronautics Research Group University of Southampton United Kingdom E: hglewis@soton.ac.uk T: +44 (0) 23 8059 3880 W: http://www.soton.ac.uk/~hglewis