Meteoroid and debris models and tools in SPENVIS H. Ludwig D. Heynderickx BIRA, Ringlaan 3, B-1180 Brussel, Belgium

Radiation environment models Implementation of MAGNETOCOSMICS (Geant4) Implementation of radiation belt models POLE GEO electron model SAMPEX/PET dynamic LEO proton model Jovian radiation belts Implementation of solar energetic proton models MSU model (Nymmik) ESP model for solar minimum (PSYCHIC) Extend the energy range of the JPL model below 5MeV and above 100MeV Upgrade of the orbit generator implement new trajectory types: hyperbolic, parabolic, interplanetary, escape modify other models and tools that use the orbit generator introduce flags for coordinate systems

Meteoroids and Orbital Debris Meteoroids originate from the asteroid belts and orbit around the Sun Space debris originate from break-ups of satellites and rocket upper stages Statistical meteoroid and debris flux models focus on particles with diameters between approximately 0.1m and 1cm Typical impact velocities: Debris: 10km/s Meteoroids: 20km/s

Damage Caused by Hypervelocity Impacts on Spacecraft Damage increases with particle size: 0.1m – 10m: Degradation of spacecraft surfaces and sensitive equipment (mirrors, optical sensors, …) 50m - 500m: Penetration of outer spacecraft coatings, foils, solar cells > 1mm: Penetration of exposed tanks, serious damage to impacted spacecraft component > 1cm: Complete destruction of impacted spacecraft component from G. Drolshagen, Hypervelocity impact effects on spacecraft, 2001

Meteoroids and Orbital Debris in Space Impact flux of particles on a randomly tumbling plate in LEO MASTER2001 debris model Divine-Staubach meteoroid model Impactor diameter [m] Cumulative flux [1/m 2 /yr]

Impact Risk Assessment Calculate the number of impacting particles (impact flux) using meteoroid and space debris flux models Use a suitable particle-wall interaction model to discriminate penetrating from non-penetrating particles Combine the flux model with the particle-wall interaction model to obtain the number of penetrating particles per unit area and time (failure flux)

Particle-Wall Interaction Models (“Damage Equations”) Empirical damage law defining the threshold particle diameter d p th for penetrating a wall of thickness t at velocity v and angle  Derived from test shot data Crater and hole size equations Single wall ballistic limit equation for maximum target thickness that can be penetrated:

Obtaining the number of penetrations For each impact velocity and angle, calculate the corresponding threshold particle diameter d p th (v,) Calculate the impact flux for an environment in which the smallest particle diameter is d p th (v,) Take the average of this flux over all impact velocities and angles according to the proper velocity and angular distribution

SPENVIS M/OD Calculation Tool (under development) Calculates the impact and failure fluxes to a plate on orbit Plate may have arbitrary orientation (fixed with respect to flight direction, sun-pointing, …) or may instead be randomly tumbling Flux models: Already included: NASA90 (debris), Grün (meteoroids) Planned: MASTER 200x (debris), Divine-Staubach (meteoroids) Damage equations: Single wall and double wall ballistic limit equations Crater size equations Calculation of cratered area, as well as average impact velocity and average impact angle To become available in December 2005