1. Origin of the Solar System
Planetary geophysics 2017

2. The Solar System

3. Evolution of the material in the Universe

4. Protoplanetary disk

5. Protoplanetary disk evolution

6. Crystalization sequence of solids

7. Planetesimals and protoplanets
Planetesimals are small objects (up to 100 m in diameter) which are formed by dust aggregation and collisions.
Protoplanets are larger objects formed by collisions of planetesimals. Thermal metamorphism and differentiation can occur in protoplanets.

8. Solar element abundances

10. Evolution of protoplanets
Frequent impacts and collisions
Growth vs. fragmentation
Heating and melting
Internal
Short-lived radionuclides (60Fe T1/2 = 1.5 Myr, 26Al T1/2 = 0.7 Myr)
Crystallization heat
Gravitational heat
Objects larger that approx. 300 km could have molten interiors
External
Impacts (in early Solar System evolution maybe more significant than internal sources)
Thermal metamorphism
Differentiation

11. Planetesimals and protoplanets

12. Chronology of the Solar System

13. Asteroids Asteroids are minor, rocky bodies of our Solar System
Size comparison of asteroid Vesta (525 km) and Ceres (950 km)
to our Moon (3400 km)
Asteroids are minor, rocky bodies of our Solar System
Their diameter varies from several meters to hundreds of kilometers (950 km for Ceres)
Most of rocky asteroids are orbiting between Mars and Jupiter, forming the main asteroid belt, or in jovian Lagrangian points (Trojan asteroids)
Recently, large population of icy bodies was discovered beyond orbit of Neptun (TNO’s)
Some of the asteroids have moon or are binary objects
Some are orbiting on trajectories approaching or crossing orbit of the Earth (Near Earth Asteroids, NEA)
Asteroid Ida (35 km) and its moon Dactyl

14. Planetary migration – Nice model

15. Asteroid belt

16. Asteroid belt

17. Asteroid belt

18. Asteroid belt
Snow line
~ 150 K

19. Asteroid belt

20. How to sample an asteroid
Meteorites are fragments of asteroids, moons and planets sent on Earth-crossing trajectories
The orbit of most of them originates in the main asteroid belt

21. Cosmic ray exposure ages in meteorites

22. History of meteorites
Meteorites were long time thought to be of terrestrial (volcanic) or supernatural in origin
The oldest observed and recorded fall is the Nogata meteorite (L6 chondrite) that fell in Japan in the year 861
1492 – fall of Ensisheim meteorite was depicted in woodcut (second oldest documented meteorite fall
The first book describing meteorites as extraterrestrial rocks is by Ernst Chladni (1794, Über den Ursprung der von Pallas gefundenen und anderer ihr ähnlicher Eisenmassen, und über einige damit in Verbindung stehende Naturerscheinungen)

23. Basic classification of meteorites
Stony meteorites
Chondrites
Ordinary chondrites
Carbonaceous chondrites
Enstatite chondrites
Achondrites
Primitive
Differentiated
Iron meteorites
Stony-iron meteorites

24. Classification of meteorites

25. Chondrites Contain chondrules
FeO/Fe ratio indicates oxidation conditions
C-chondrites are most oxidized (rich in volatiles, hydrothermal alteration on parent bodies), origin in cold environment
E-chondrites are most reduced, origin in hot environment

26. Chondrules Chondrules are 1-3 mm sized spherical objects
Bonded together by matrix (like sediment)
Rapidly crystalized droplets
Origin of chondrules by flash-heating (1000°C) caused by pressure waves in solar nebula
Glassy or crystalline (porphyritic, radial, barred, cryptocrystalline, granular)

27. Chondrites - classification
Chondrite group and petrographic type 1 2 3 4 5 6
< 200°C °C
Aqueous alteration
600°C °C > 750°C
Thermal metamorphism
Chondrules
Absent
Sparse
Abundant, distinct
Increasingly indistinct
Carbonaceous chondrites CI CM CR CO CV CK
R chondrites R
Ordinary chondrites LL L H
Enstatite chondrites EL EH

28. Shock scale
Stöffler et al. 1991

29. Shock scale
Stöffler et al. 1991

30. Ordinary chondrites
Composed of silicates (olivine, orthopyroxene), metal, sulfides
LL most oxidized, E most reduced
Various shock level,
Common presence of impact melt veins or impact breccias

31. Carbonaceous chondrites
Composed of silicates (olivine, serpentine), oxides, sulfides)
Presence of organics, water
CAIs
CI most primitive (most close to solar element abundances)
Some contain abundant FeNi metal (CH, CB)
Allende CV

32. Evolution of meteorite parent bodies

33. Not that simple… Several contradicting theories exist:
External (impact) vs. internal (radioisotope, crystallization, gravity) heating – thus, the onion shell structure may be reversed (more metamorphosed on top)!
Hydrothermal alteration of carbonaceos chondrites – individual or heterogeneous layered (even on partly differentiated) parent bodies

34. Allan Hills 81005 lunar meteorite
Achondrites
Similar to basaltic, plutonic, or mantle cumulate rocks
Primitive – chondritic composition, fine-grained whole-rock melt (Acapulconites, Lodranites, Winonaites)
Differentiated – mantial or crustal material of differentiated bodies
Breccias often present
Origin: asteroids (Angrites, Aubrites, Ureilites, Brachinites), Moon, Mars (SNC), Vesta (HED)
Allan Hills lunar meteorite

35. Iron and stony-iron meteorites
Most likely cores of early protoplanets
Structural classification (hexahedrites, octahedrites, ataxites)
Chemical classification (groups I-IV) based on Ga, Ge, and IR content
Made of FeNi kamacite (low Ni, α-pahse, bcc) and taenite (hign Ni, -phase, fcc)
Some show Widmanstätten pattern (exsolution of kamacite and taenite)
Stony irons –mixtures of olivine and metal
Pallasites are mixtures of iron and olivine (core-mantle boundary)
Mesosiderites are breccias with metal clasts

36. Meteorite chronology

37. Magnetic susceptibility of meteorites

38. Stardust and comet Wild 2

39. Stardust and comet Wild 2
The recovered grains include organic rich compounds as well as high temperature phases.
Early Solar System material mixing.

40. Presolar grains

41. Oxygen isotopes

42. Meteoritres and asteroids the scale difference
Itokawa asteroid
Hayabusa space probe B
550 m
Detail of the surface
Bjurböle meteorite C D
1 m
5 cm

43. What to remember
Protoplanetary disk and crystallization sequence of solids
Planetary migration
Asteroids are remains of old planetesimals and protoplanets
Collisions and impacts
Mixing of material within Solar System
Snow line
Meteorites bring samples from various regions of asteroid belt
Meteorite classification, mineralogy, chemistry