Planetary formation What a Nice model Density Early Solar System KOALA Conclusion The asteroids and the early Solar System B. Carry European Space Agency 1/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Resume of planetary formation Step-by-step a. Gas & dust cloud contracts b. Disk forms c. Rotation, accumulation @ center d. A star is born e. Accretion within the disk f. Planetary system 2/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Resume of planetary formation Step-by-step a. Gas & dust cloud contracts b. Disk forms c. Rotation, accumulation @ center d. A star is born e. Accretion within the disk f. Planetary system 2/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Resume of planetary formation Step-by-step a. Gas & dust cloud contracts b. Disk forms c. Rotation, accumulation @ center d. A star is born e. Accretion within the disk f. Planetary system 2/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Interest of asteroids 1. Large population ◦ 600 000 objects (several millions) ◦ Sample the whole Solar System [1{100 AU] ◦ Sample all the compositions [rocks ! ices] 2. Primitive population ◦ Small objects [km] ◦ Internal energy ≈ null ◦ No endogenous activity . Direct witnesses of the early Solar System 3/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion The 1982's view 1. Asteroid taxonomy • Reflectance • Albedo • 24 classes 2. Strong gradient in 1 AU • X : Iron cores • V,A : Crust & Mantle Bus-DeMeo Taxonomy Key • S : Melted silicates S-complex 1.5 S1 Sa S) S* S+ • C : Most primitive 0.45 2.45 • D,T : Comet nucleus ? C-complex BC C& Cg C,h Ch X-complex 3. Paradigm from 1982 X X' Xe X- ◦ Survey of 800 asteroids End members ◦ Visible spectrometry DK L T I In-situ formation A OQ R V 4/25 B. Carry, ESA, 2012-10-104 http://smass.mit.edu/busdemeoclass.html Planetary formation What a Nice model Density Early Solar System KOALA Conclusion The 1982's view 1. Asteroid taxonomy • Reflectance • Albedo • 24 classes 2. Strong gradient in 1 AU • X : Iron cores • V,A : Crust & Mantle Bus-DeMeo Taxonomy Key • S : Melted silicates S-complex Ordinary chondrites 1.5 S1 Sa S) S* S+ • C : Most primitive 0.45 2.45 • D,T : Comet nucleus ? C-complex Carbonaceous chondrites? BC? C& Cg C,h Ch X-complex Nickel-iron - Stony iron - Entatites 3. Paradigm from 1982 X X' Xe X- ◦ Survey of 800 asteroids End members ◦ Visible spectrometry ??? ? DK L T In-situ formation I ??? ??? A OQ R V 4/25 B. Carry, ESA, 2012-10-104 http://smass.mit.edu/busdemeoclass.html Planetary formation What a Nice model Density Early Solar System KOALA Conclusion The 1982's view 1. Asteroid taxonomy Relative fractions of classes • Reflectance • Albedo • 24 classes 2. Strong gradient in 1 AU • X : Iron cores • V,A : Crust & Mantle Adapted from Gradie and Tedesco, 1982 • S : Melted silicates • C : Most primitive • D,T : Comet nucleus ? 3. Paradigm from 1982 ◦ Survey of 800 asteroids ◦ Visible spectrometry I In-situ formation 4/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion The 1982's view 1. Asteroid taxonomy Relative fractions of classes • Reflectance • Albedo • 24 classes 2. Strong gradient in 1 AU • X : Iron cores • V,A : Crust & Mantle Adapted from Gradie and Tedesco, 1982 • S : Melted silicates • C : Most primitive • D,T : Comet nucleus ? 3. Paradigm from 1982 ◦ Survey of 800 asteroids ◦ Visible spectrometry I In-situ formation 4/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Some open questions 20 10 18 Nectaris (3.90 Gy) 10 Imbrium (3.85 Gy) Orientale (3.82 Gy?) 16 10 14 10 3.90 - 3.82 Gy 12 4.12 - 3.82 Gy 10 LHB Mass (g/year) 10 10 Apollo 17 Apollo 12 8 10 4.04.5 3.5 3.0 2.5 2.0 Age (109 years) • Late Heavy Bombardment • • Planetary migration • Excess cratering @ 3.8 Gy Hot Jupiters Thick disk for accretion Migration within disk Tiny fraction remains Solar System ? 5/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion The Grand Tack & Nice model A. Grand Tack { 100 kyr • Jupiter inward migration • Stopped by Saturn • Inner Solar System B. The Nice Model { 700 Myr • Jupiter-Saturn interaction • Neptune pushed out • Outer Solar System Overall result Walsh et al. 2011 • Complete mixing • Removal of 99% mass 6/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion The Grand Tack & Nice model A. Grand Tack { 100 kyr • Jupiter inward migration • Stopped by Saturn • Inner Solar System B. The Nice Model { 700 Myr • Jupiter-Saturn interaction • Neptune pushed out • Outer Solar System Overall result • Complete mixing • Removal of 99% mass Gomes et al. 2005 6/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion But... and the 1982's view ? Adapted from Gradie and Tedesco, 1982 In-situ formation ? 7/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion But... and the 1982's view ? Adapted from Gradie and Tedesco, 1982 In-situ formation ? Number instead of mass { Only largest asteroids 7/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion The era of all-sky surveys 1. Number of discoveries sky-rocketed in 30 years • 10,000 in 1982 ... 600,000 in 2012 • Completeness vastly improved (2{5 km) I Dynamic models 2. Compositional information available for thousands of asteroids • SDSS : visible colours for 100,000 asteroids (vs 800) • WISE : albedo for 150,000 asteroids (vs 2000) I Large-scale taxonomy 3. Density is needed to convert numbers in mass • Limiting factor I How do we measure density ? 8/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion The era of all-sky surveys 1. Number of discoveries sky-rocketed in 30 years • 10,000 in 1982 ... 600,000 in 2012 • Completeness vastly improved (2{5 km) I Dynamic models 2. Compositional information available for thousands of asteroids • SDSS : visible colours for 100,000 asteroids (vs 800) • WISE : albedo for 150,000 asteroids (vs 2000) I Large-scale taxonomy 3. Density is needed to convert numbers in mass • Limiting factor I How do we measure density ? 8/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion The era of all-sky surveys 1. Number of discoveries sky-rocketed in 30 years • 10,000 in 1982 ... 600,000 in 2012 • Completeness vastly improved (2{5 km) I Dynamic models 2. Compositional information available for thousands of asteroids • SDSS : visible colours for 100,000 asteroids (vs 800) • WISE : albedo for 150,000 asteroids (vs 2000) I Large-scale taxonomy 3. Density is needed to convert numbers in mass • Limiting factor I How do we measure density ? 8/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion How do we measure density ? M ρ = V 9/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion How do we measure density ? M ρ = V 10/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Mass measurements 1. Flyby Gravitational interaction ◦ Asteroid - Probe ◦ Precise but rare 2. Satellites ◦ Asteroid - Satellite ◦ Precise and about common 3. Deflection ◦ Asteroid - Asteroid ◦ Low precision but common 4. Ephemeris ◦ Asteroid - Everything ◦ Low precision but common 11/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Mass measurements 1. Flyby Gravitational interaction ◦ Asteroid - Probe ◦ Precise but rare 2. Satellites ◦ Asteroid - Satellite ◦ Precise and about common 3. Deflection ◦ Asteroid - Asteroid ◦ Low precision but common 4. Ephemeris ◦ Asteroid - Everything ◦ Low precision but common 11/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion How do we measure density ? M ρ = V 12/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Volume measurements M ρ = V • Masses : 287 • Diameters : ◦ IRAS : 2228 ◦ AKARI : 10 000 ◦ WISE : 150 000 ◦ Gaia : 10 000 13/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Volume measurements s M δρ δM2 δV 2 ρ = = + V ρ M V s δM2 δR2 • Masses : 287 = + 9 M R • Diameters : ◦ IRAS : 2228 ◦ AKARI : 10 000 ◦ WISE : 150 000 ◦ Gaia : 10 000 13/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Volume measurements s M δρ δM2 δV 2 ρ = = + V ρ M V s δM2 δR2 • Masses : 287 = + 9 M R • Diameters : ◦ IRAS : 2228 ◦ AKARI : 10 000 The Volume ◦ WISE : 150 000 is (easily) the ◦ Gaia : 10 000 Limiting Factor 13/25 B. Carry, ESA, 2012-10-104 Planetary formation What a Nice model Density Early Solar System KOALA Conclusion Summary of accuracy 14/25 B.