Making impact craters from numbers

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Making impact craters from numbers

• Natalia Artemieva
• artemeva_at_psi.edu
• Tucson-2007

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Content

• How to produce billions of numbers quickly?
• How to deal with these billions?
• Crater shape
• Seismic images
• Petrology and shock metamorphism
• Geophysics gravity and magnetic anomalies
• Ejecta and material exchange between planets

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Impact craters on the Earth and on other planets
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How to generate numbers?

• Navie-Stocks equations conservation of mass,
  momentum and energy
• Density(3)Energy(3)Concentration (2)
  Velocity(3)Stresses(6).. 11-17.
• Discretization of space
• 300?300?300 27?106
• Discretization of time millions of steps
• In total up to a billion of numbers on each
  time step

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How to make them visible?

• Look at them yourself for years
• Ask a kind person to extract something useful
• Use post-processing
• ø - low density
• ? - high density

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Density distribution and crater shape

• Bosumtwi crater
• 10-km-diameter, 1Myr
• Well-preserved and drilled recently
• Numerical shape is similar to a real one, but not
  identical
• Central uplift
• Rim height
• Too deep
• Problems with material density after the impact
  (dilatancy)

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Bake the crater

• Change density according to damage, temperature,
  and lithostatic pressure
• Define gravity anomaly

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Paint the crater

• Displacement of target material
• Maximum shock compression
• Correlation with seismic data and minerals in
  drill cores

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Measure its temperature

• Amount of melt and melt distribution
• Post-impact hydrothermal activity
• Density Temperature Mineralogy Magnetic
  signatures

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Ejecta what is outside the bowl?

• Velocity above escape and solid meteorites from
  Mars and Moon
• High velocity (below escape) secondary craters,
  tektites, distal ejecta
• Low velocity proximal ejecta, ejecta blankets.

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Ejecta meteorites from other planets

• Velocity above escape
• Moon 2.4 km/s, no atmosphere
• Mars 5 km/s, thin atmosphere
• Earth 11 km/s, thick atmosphere
• Solid (Plt 50 GPa)
• Correlation with observations
• Pre-impact depth
• Maximum compression and maximum temperature
• Pre-atmospheric size

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Life transfer?

• Impact and ejection
• High pressure and high temperature
• Flight in space
• Vacuum
• Low temperature
• Cosmic rays
• Atmospheric entry
• Heating and ablation

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Do we need more numbers?

• More cells is better, but computational time
  increases dramatically T h-4.
• Parallel processes
• Adaptive mesh
• More stable computational scheme
• Still unresolved problems
• Micro-effects versus macro-events
• Chemical reactions

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Recent publications

• Artemieva N.A. and Ivanov B.A. (2004) Launch of
  martian meteorites in oblique impacts. Icarus,
  171, 84-101.
• Artemieva, N., T. Karp, and B. Milkereit (2004),
  Investigating the Lake Bosumtwi impact structure
  Insight from numerical modeling, Geochem.
  Geophys. Geosyst., 5, Q11016, doi10.1029/2004GC00
  0733.
• Fritz J., Artemieva N., Greshake A. (2005)
  Ejection of Martian meteorites petrological
  data and numerical modeling. Meteoritics
  Planetary Science 40, Nr 9/10, 13931411.
• McEwen A.S., B. S. Preblich, E. P. Turtle, N.
  Artemieva, M. P. Golombek, M. Hurst, R. L. Kirk,
  D. M. Burr, P. R. Christensen (2005) The Rayed
  Crater Zunil and Interpretations of Small Impact
  Craters on Mars. Icarus, 176, 351-381.
• Artemieva, N., L. Hood, and B. A. Ivanov (2005),
  Impact demagnetisation of the Martian crust
  Primaries versus secondaries, Geophys. Res.
  Lett., 32 (18), L22204, doi10.1029/2005GL024385.
• Artemieva N., Lunine J. (2005) Impact Cratering
  on Titan II Global Melt, Ejecta, and Atmosphere
  Accretion. Icarus 175 522-533.
• E. Pierazzo, N.A. Artemieva, and B.A. Ivanov
  (2005) Starting Conditions for Hydrothermal
  Systems Underneath Martian Craters Hydrocode
  Modeling. GSA Special Paper, 384, 443-457.
• H. A. Ugalde, N. Artemieva, B. Milkereit (2005)
  Magnetization on impact structures constraints
  from numerical modeling and petrophysics. GSA
  Special Paper, 384, 25-42.
• Artemieva N. (2007) Possible reasons of shock
  melt deficiency in the Bosumtwi drill cores. MPS
  42, issues 4/5, 883-894.
• Stöffler, D. and 9 co-authors (2007) Experimental
  evidence for the potential impact ejection of
  viable microorganisms from Mars and Mars-like
  planets. Icarus 186, 585-588.
• Fritz J., Tagle R., Artemieva N. (2007) Lunar
  Helium-3 in marine sediments Implications for a
  late Eocene asteroid shower. Icarus 189, 591-594.