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

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

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:
1. Space “Health” Index
– Provides context and calibration for
environmental impact rating
– Score out of 100
2. Environmental Impact Rating
– Measure effect of future spacecraft on debris
environment
– Input data provided by manufacturer/operator
– Score out of 100
4
“Health” Index
Environmental
Impact Rating
Calibration
1.
2.
User Inputs
SPACECRAFT DATA, APPLIED
MITIGATION MEASURES

5. “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

6. 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

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

8. 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

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:
– 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

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

13. 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

14. 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

15. 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%
Representative „Certificate‟

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
16

17. Contact:
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
http:// www.fp7-accord.eu
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 Holger Krag (ESA Space Debris Office)