Space Debris Environment Impact Rating System 1 University of Southampton 2 PHS Space Ltd. H.G. Lewis 1, S.G. George 1, B.S. Schwarz 1 & P.H. Stokes 2

Introduction: ACCORD 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 an environment impact rating system Alignment of Capability and Capacity for the Objective of Reducing Debris

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

Environment Impact Rating System Two aspects: 1.Space “Health” Index –Provides context and calibration for environmental impact rating –Score out of Environmental Impact Rating –Measure effect of future spacecraft on debris environment –Input data provided by manufacturer/operator –Score out of “Health” Index Environmental Impact Rating Calibration User Inputs SPACECRAFT DATA, APPLIED MITIGATION MEASURES

“ Health ” ~ Assess the “health” of the space environment with respect to 2 goals: 1.Widespread Implementation of Mitigation Measures A.Protection of Service B.Legacy of Service 2.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 1. Space “Health” Index Leads to a measure of a “healthy” space environment to be used in the impact rating calculation A measure of the long-term sustainability of outer space activities

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

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 7 Combined to give overall “health” of LEO (deg)

Goal 1A: Protection of Service Compliance with mitigation guidelines & good practices that are implemented to avoid loss during operations –Impact shielding, collision avoidance 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

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

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 1 st May 2009 –Population of objects ≥ 10 cm on 1 st 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

Data Sources DAMAGE Simulations: –Capacity of 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 11

Data Sources

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

Rating Parameters: 1.Debris score for the prescribed orbital region (how “crowded” the region is) 2.The capacity of applied mitigation measures to limit the generation of new debris (from DAMAGE) 3.How the prospective spacecraft affects the “health” index in the given orbital region (re-calculate “health” index) 2. Environmental Impact Rating Environmental Impact Rating Defines LEO Region Orbit Data Altitude Inclination Mitigation Measures Used How Mitigation Measures are Implemented User Inputs Crowding of Debris in LEO Region Capacity of Mitigation to Limit Future Debris Modification to “Health” Index for LEO Region “Health” Index All scores expressed out of 100

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 % +0.01% Representative ‘Certificate’

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 16

Contact: Dr. Hugh G. Lewis Astronautics Research Group University of Southampton United Kingdom E: T: +44 (0) W: Funding provided by the European Union Framework 7 Programme (Project No ). Thanks to Carsten Wiedemann (TU Braunschweig), Adam White (University of Southampton), Richard Tremayne-Smith, and Holger Krag (ESA Space Debris Office)