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## The effect of modelling assumptions on predictions of the space debris environme

Laudig, Michele, Food Editor and Reporter has reference to this Academic Journal, PHwiki organized this Journal The effect of modelling assumptions on predictions of the space debris environment R. Blake in addition to H.G. LewisAstronautics Research Group, Faculty of Engineering & the Environment, University of Southampton, UKIAC-14-A6.2.4Evolutionary models are used to guide technical solutions to the space debris problemThese tools incorporate simplified models as long as estimating orbital motion in addition to collision probability, as long as exampleSimulations using these models make assumptions to reduce the many degrees of freedom that existSome research has already been done to underst in addition to the influence of assumptions made about external drivers (e.g. solar activity)Little research has been done to underst in addition to the influence of the model simplifications/assumptionsIntroductionFocus of this presentation is the Cube approachExternal driversSolar activityLaunch trafficExplosionsCompliance with mitigation measures

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Evaluates collision probabilities between orbiting objects using a sampling in time approach: Number of collisions: Collision rate: Spatial density:The Cube ApproachUdTwo identical objects i in addition to j in circular, polar orbits of a = 7000 km in addition to intersecting at 90:Idealised caseRelative velocity:Residential probability:Collision rate as long as this case:Idealised caseCombined collision cross-sectional area:

Space Debris Environment Tool Kit:Orbit propagator & Cube approach implemented in PythonImplementation in SDETKComparison of collision rates:Theory v Implementation in SDETKCollision rate is inversely proportional to the cube size:Increasing time-interval or decreasing cube size reduces the consistency of collision rate estimatesCube sizes 10 km, in addition to Time-intervals 0.05 days, are preferredIncreasing the number of Monte Carlo runs also enables good sampling of the spaceFindingsComputational cost

DAMAGE: full LEO-to-GEO evolutionary modelUses target-centred version of Cube:Cube Implementation in DAMAGEIdentifies all cases where a debris object resides within a bounding sphere centred on the targetSize of volume element is proportional to the size of the cube element11LEO 10 cm Population (May 2009)ESA MASTER 2009 population seen in DAMAGE29,370 objects 10 cmOverall collision rate estimates:DAMAGE Results

For the idealised, two-object case the number of co-occurring pairs in the cube remains constant but the volume increases (A): collision rate decreasesIn DAMAGE simulation, the number of unique co-occurring pairs in each cube increases as volume increases (B) or (C): overall collision rate appears ~constantDAMAGE ResultsABCCollision rate between two orbiting objects is inversely proportional to the cube size:Shown in theoryObserved in SDETK implementationIncreasing number of Monte Carlo runs in addition to cube size, or decreasing time-interval improves the consistency of collision rate estimatesDefault parameters in DAMAGE ( in addition to other evolutionary models using Cube) likely to be sub-optimalCollision rates appear ~constant as long as changing cube sizeDifficult to address due to computational costFurther research is required to underst in addition to implicationsConclusionsThank you as long as your attention Contact: hglewis@soton.ac.ukThanks to Holger Krag (ESA Space Debris Office) as long as permission to use the MASTER reference population, in addition to Aleks in addition to er Lidtke (University of Southampton) as long as valuable discussions about the work

## Laudig, Michele Food Editor and Reporter

Laudig, Michele is from United States and they belong to Phoenix New Times and they are from Phoenix, United States got related to this Particular Journal. and Laudig, Michele deal with the subjects like Food; Restaurants/Dining

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