1. Meteorites: Rocks from space

2. Leonid meteor shower, 1998 European Fireball Network image Meteoroid Meteor (fireball) Meteorite

3. 1992 Peekskill fireball video clips (How to turn a $300 car into one worth $10,000.)

5. Results of ablation: fusion crust, thumbprints, fragmentation

7. Where do meteorites come from? Well-photographed meteors which have produced meteorites: Pribram, Czechoslovakia1959H5 Lost City, Oklahoma1970H5 Innisfree, Alberta1977LL5 Peekskill, New York1992H6 Tagish Lake, British Columbia2000CM1 Tagish Lake fireball

8. Meteoroid orbits: aphelia between Mars & Jupiter (asteroid belt) Jupiter Mars

9. Spectral reflectance of various meteorites & asteroids

10. How do meteorites get to the Earth? (1) Perturbations by Jupiter can put asteroidal material into Earth-crossing orbits (Kirkwood gap clearing). (2) The Yarkovsky Effect can cause rotating m-sized objects to spiral inwards to (or outwards from) the sun. Cosmic-ray exposure (CRE) ages of meteorites (~1 Ma to ~0.5 Ga) give travel time needed for m-sized object-- consistent with Yarkovsky Effect

11. Meteorites: different types DesignationProportion of metal & silicate Stony>> 50 % silicate Stony-iron ~ 50% metal, ~ 50% silicate) Iron>> 50% metal alloy

12. Meteorite types & parent bodies # parent DesignationClass & rock typesbodies* Stonychondrites: agglomerate> 13 Stonyachondrites: igneous, breccia> 8 Stony-ironpallasite: igneous> 3 Stony-ironmesosiderite: meta-breccia1 (2) Ironmany groups: igneous50-80? * as inferred from chemical & isotopic studies

13. Meteorites: different types DesignationType of rock Chondriteagglomerate-- never melted (stony) All elseigneous; impact breccias-- (stony, stony- melted at least once iron, iron)

14. Chondrites All other rocks

15. Undifferentiated meteorites: chondrites

16. Chondrites Meteorite type most often seen to fall (85.6%) Earliest-formed rocks (ages: ~4.55 b.y.) Formed in solar nebula Solar-like bulk composition (planetary building blocks)

17. protoplanetary disks

18. Chondrites have “solar composition” for most elements

19. Chondrites most contain chondrules mm to sub-mm-sized objects formed as melted dispersed objects some contain refractory inclusions (CAIs) mm to cm-sized objects formed at high temperatures in solar nebula some contain pre-solar grains grains formed around other stars some contain pre-biotic organic matter

20. “Chondritic texture”: an agglomeration of chondrules and fine-grained matrix matrix chondrules 0.2 mm

21. CAIs contains CAIs and pre-solar grains

22. CAIs Carbonaceous chondrite chondrules Image: J.A. Wood

23. Contains pre-biotic organic material

24. Carbonaceous vs. Ordinary Chondrites

25. Shocked chondrite: the 1992 Peekskill Fireball meteorite

26. Differentiated meteorites DAG 485 (urelilite) Gibeon (IVA iron)Millbillillie (eucrite)

27. Achondrite - any stony meteorite NOT a chondrite - samples of crusts and mantles of differentiated asteroids, the Moon, and Mars

28. Big! iron meteorite Irons - samples of the cores of differentiated asteroids

29. Iron meteorite: slow-cooling in a metallic core

31. Mesosiderite origin: collision of a stripped metal core & another differentiated asteroid?

32. Studies of meteorites provide evidence for: 1) widespread transient, high-T heating events in the solar nebula -- to form chondrules, CAIs 2) gas-dust chemical equilibrium in the solar nebula -- “equilibrium condensation model” valid 3) incomplete mixing & heating of dust in the solar nebula -- pre-solar material survived solar system formation!

33. Studies of meteorites provide evidence for: 4) short-lived heat sources in meteorite parent bodies -- many asteroids melted & differentiated -- many asteroids metamorphosed & aqueously altered -- short-lived radionuclides, induction heating (?) were important in early solar system 5) water in many meteorite parent bodies -- in the form of ice or hydrated materials -- water in some asteroids too

34. Studies of meteorites provide evidence for: 6) pre-biotic organic synthesis -- precursor materials for life formed in space! 7) impact & collision processes -- collisions important, probably even early in solar system -- asteroids may have been disrupted & reassembled

35. Studies of meteorites provide evidence for: 8) interplanetary rock-swapping -- we have martian & lunar meteorites -- this has implications for life