The Next 100 Years Projection of Debris in GEO Space Systems Dynamics Laboratory Yuya Mimasu 1st March, 2007

Contents  Background  Objective  Modeling Concept  Projection Scenario  Result of Projection  Summary

Background Geosynchronous Earth Orbit (GEO) is the most valuable resource, and many satellites have been launched into this region. At present, Collision Hazard due to traffic jam is a serious issue. Mitigation Measures  Measurement  Modeling  Protection  Mitigation Debris Environment around Earth

Objective  We project the next 100 years by repeating insertion of the 8-year traffic for the years 1998 through 2005 as one cycle of projection by using GEODEEM. GEODEEM is GEO Debris Environmental Evolutionary Model developed at Kyushu University.

Modeling Concept Initial Condition Traffic at 1 st January 2006 Annual Number of Actual Launches in 1998 Annual Number of Actual Disposed Satellites in 1998 Traffic at 2007 Annual Number of Actual Launches in 1999 Annual Number of Actual Disposed Satellites in 1999 Traffic at Repeat during 100 years Insertion Data Explosions Collisions Explosions Collisions Explosion is occurred because of residual propellant or some failures.

Category  Space objects are categorized according to their longitude stability as shown in following table. CategoriesLongitude StabilityGEO crossing Operational SatelliteConstantYes Abandoned SatelliteLibrating/OscillatingYes Disposed SatelliteDriftingNo Rocket BodyDriftingNo Fragments crossing GEODriftingYes Fragments staying above/under GEODriftingNo

Operational Satellites Disposed Satellites Abandoned Satellites Post Mission Launch Rocket Bodies Earth Accumulation Process Normal Process Geostationary Ring Orbit more than 300 km above GEO

Operational Satellites Disposed Satellites Abandoned Satellites Launch Rocket Bodies Earth Accumulation Process Collision or Explosion Geostationary Ring Orbit more than 300 km above GEO

Initial Population Population of each category at initial state CategoryX1X2X3X4X5X6 Number X1: Operational Satellites X2: Abandoned Satellites X3: Disposed Satellites X4: Rocket Bodies X5: Fragments crossing GEO X6: Fragments staying above/under GEO

Propagator  The propagator is adopted to the Debris  Perturbations  Earth’s gravitational Attraction  Third Body (Sun and Moon)  Solar Radiation Pressure  Solution Analytical Solution

Collision Probability  Collision Probability is calculated by using following equation.  t: time that the object spends in the sphere p 1, p 2 : probabilities that objects will be in sphere during one revolution P: orbital period, V: volume of sphere  V: volume of overlapping portion A 12 : sum of representative area of two objects,

Projection Scenario  Economical and Political situation does not change from present state.  The increasing tendency of space objects will not change in 100 years. Assumption Scenario Project from 1 st January 2006 with 8-year traffic for the years 1998 through 2005 as one cycle of projection. Business as usual

Results of Projection Projection without DisposalProjection with Actual Disposal The Number of Collisions in 30 Monte Carlo run

Results of Projection Projection without DisposalProjection with Actual Disposal The Average Number of Explosions in 30 Monte Carlo run

Results of Projection Projection without DisposalProjection with Actual Disposal Population of Space Objects in Several Categories

Results of Projection Projection without DisposalProjection with Actual Disposal Distribution of Population of Space objects > 10 cm

Summary  Modification in this study  Update Initial Condition.  Update Launch History.  Inserted Traffic of Actual Disposed Satellite.  Conclusions  Although the disposed satellites lead to a decrease of population on GEO and collision probability, the population of debris do not change dramatically.  To decrease the hazard of debris, we need to decrease the number of explosions.

ご清聴ありがとうございました． (Goseityou Arigatou Gozaimasita)