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    English presentation odoardi English presentation odoardi Presentation Transcript

    • Laboratory experiments for studying Collisional Disruption in the Solar System Based on a Donald R. Davis’ article English presentation Daniel Odoardi Monday, the 6th of December Master EFTIS IUFM de Nice - UNSA
    • Table of contents
      • Why to study collisional disruptions ?
      • Types of collisional outcomes
      • Fragmentation modes
      • Experimental laws
      • Extrapolation to the Solar System
    • Why to study collisional disruptions ?
      • Moon formation caused by a collision between a Mars-size body and the Earth
      • Extinction of the dinosaur (impact in the yucatan 65 million years ago)
      • More than 2000 collisions with a body of a mass greater than 1 kilogram per day
      • Anticipate the consequences of a collision between an asteroid and the Earth
      • Understand the Solar System formation
      • Study of the chondrites : the elementary bricks of the Solar System
      • Collisions between small bodies is the origin of planet formation
    • Type of collisional outcomes A question of velocity
      • Slow velocity impact
          • Accretion
          • Inelastic rebound
      • High velocity impact
          • Cratering
          • Fragmentation
    • Fragmentation modes Question of velocity and target material
      • Rock
          • Low velocity
          • High velocity
      • Ice
          • Low velocity
          • High vleocity
      • Iron
          • High velocity
    • Some definitions
      • Fragmentation degree : f d = M b /M o
          • M b : Mass of the biggest fragment
          • M o : Mass of the original body
          • If f d < 0.5  Fragmentation
          • If f d > 0.5  Cratering
      • Specific energy : Q = E tot / mass
          • It is a kinetic energy
    • The experimental laws
      • 1st experimental law : f d = K . Q -a
        • Where K and a are empirically determined
      • 2nd experimental law : N(>m) = (M b /m) b
      • N(>m) = number of fragments with a mass greather than m and b = 1/(1+f d )
      • Actually, to use two power law gives better results
      • 3rd experimental law : V(m) = V o .(m/M o ) -r
      • V o = V o (Q) and r ~ (1-b).4/9
    • Extrapolation to the Solar System
      • Scale difficulties :
        • Asteroïds are 10 6 at 10 8 bigger than bodies studied in laboratories
        • Specific energy Q* needed to have fragmentation depends of the size of the body
      • Solutions :
        • Power law for take into account the mecanical effects  dominant for small bodies
        • Power law for take into account the gravitationnal effects  dominant for big bodies
    • Conclusions
      • Study of collisional disruptions
        • Predict the consequences of an impact with the Earth
        • Understand the Solar System formation
      • Different types of collisional outcomes
      • Different types of fragmentation modes
      • Tree experimental laws
      • Power laws for extrapolation to the Solar System
    • Thanks for your attention