Lecture 7 part 2 of the "Introduction to Planetary Science" course at EPFL/Swiss Space Center Asteroids (where do they come from?, their diversity, relation with society) http://moodle.epfl.ch/course/view.php?id=6281&lang=fr

1. Asteroids
Lecture 7
Tuesday, November 12 2013
Dr Harold Clenet, EPSL, EPFL

2. What is an asteroid?
Tuesday, November 12 2013
2
Dr Harold Clenet, EPSL, EPFL

3. Outline
•
•
Diversity among the asteroids
• The electromagnetic spectrum and asteroids characteristics
• Asteroids families
• Some physical properties
•
Tuesday, November 12 2013
Where do the asteroids come from?
• At the beginning of our Solar System
• From planetesimals to planetary embryos… and asteroids
• Detection of asteroids
Asteroids and society
• Asteroids as hazards
• Asteroids as resources
3
Dr Harold Clenet, EPSL, EPFL

4. At the beginning of our solar system
Tuesday, November 12 2013
4
Dr Harold Clenet, EPSL, EPFL

5. At the beginning of our solar system
Discs around young stars in Orion
nebula (HST image)
Tuesday, November 12 2013
5
Dr Harold Clenet, EPSL, EPFL

6. At the beginning of our solar system
Disc around the young star AU Mic
(Keck telescope)
Vertical structure
Accretion of planetesimals
Tuesday, November 12 2013
6
Dr Harold Clenet, EPSL, EPFL

7. From planetesimals to planetary embryos… and asteroids
Growth process for
planetary embryos
Tuesday, November 12 2013
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Dr Harold Clenet, EPSL, EPFL

8. From planetesimals to planetary embryos… and asteroids
The small Mars problem
and the Grand Tack Scenario
Tuesday, November 12 2013
8
Dr Harold Clenet, EPSL, EPFL

9. Detection of asteroids
Giuseppe Piazzi
(1746-1826)
Tuesday, November 12 2013
9
Dr Harold Clenet, EPSL, EPFL

10. Detection of asteroids
Tuesday, November 12 2013
10
Dr Harold Clenet, EPSL, EPFL

11. Detection of asteroids
Tuesday, November 12 2013
11
Dr Harold Clenet, EPSL, EPFL

12. Detection of asteroids
Tuesday, November 12 2013
12
Dr Harold Clenet, EPSL, EPFL

13. Outline
•
•
Diversity among the asteroids
• The electromagnetic spectrum and asteroids characteristics
• Asteroids families
• Some physical properties
•
Tuesday, November 12 2013
Where do the asteroids come from?
• At the beginning of our Solar System
• From planetesimals to planetary embryos… and asteroids
• Detection of asteroids
Asteroids and society
• Asteroids as hazards
• Asteroids as resources
13
Dr Harold Clenet, EPSL, EPFL

14. The electromagnetic spectrum and asteroids characteristics
MGS
TES - 1996
MO
GRS - 2001
Gamma spectroscopy
MO
THEMIS - 2001
MRO
SHARAD - 2005
MEx
MARSIS - 2003
Radar
MGS
MOC - 1996
Thermal infrared
MEx
HRSC - 2003
MEx
OMEGA - 2003
MRO
CTX & HiRISE - 2005
MRO
CRISM - 2005
Visible optical imagery
Visible – Near Infrared spectroscopy
Tuesday, November 12 2013
14
Dr Harold Clenet, EPSL, EPFL

15. The electromagnetic spectrum and asteroids characteristics
Planck’s law
relation between the temperature of a body and the energy flux
2 hV
E ( ,T )
2
hV
5
(e
kT
1)
h = 6.63 10-34 J.s - Planck’s constant
K = 1.38 10-23 J/s - Boltzmann’s constant
V = 3.00 108 m/s - light speed
- wavelength
T - black body temperature
Tuesday, November 12 2013
Dr Harold Clenet, EPSL, EPFL

16. The electromagnetic spectrum and asteroids characteristics
Stefan’s law
Stefan’s law is the integration of Planck’s law for at all the wavelengths
E emis
2 hV
2
1
hV
5
0
ek
Stefan’s constant :
5 , 67 . 10
8
Wm
d
2
K
T
T
4
1
4
T=6000K, Fp=Fi=73.000.000 W.m-2
T=300K, Fp=Fi=459 W.m-2
Tuesday, November 12 2013
Dr Harold Clenet, EPSL, EPFL

17. The electromagnetic spectrum and asteroids characteristics
Wien’s law
For a given temperature, Wien’s law give the wavelength
where the enerfy flux is maximal
m
T
Cst
3000
mK
T=6000K, max at 0.6 µm (middle of the visible)
T=300K, max at 10 µm (in the thermal infrared)
Tuesday, November 12 2013
Dr Harold Clenet, EPSL, EPFL

18. The electromagnetic spectrum and asteroids characteristics
Black body spectrum
Tuesday, November 12 2013
Dr Harold Clenet, EPSL, EPFL

19. The electromagnetic spectrum and asteroids characteristics
Tuesday, November 12 2013
19
Dr Harold Clenet, EPSL, EPFL

20. The electromagnetic spectrum and asteroids characteristics
2 process producing absorptions
Tuesday, November 12 2013
Dr Harold Clenet, EPSL, EPFL

21. Asteroids families
Classification of asteroids based on
their spectral shape
Tuesday, November 12 2013
21
Dr Harold Clenet, EPSL, EPFL

22. Asteroids families
Tuesday, November 12 2013
22
Dr Harold Clenet, EPSL, EPFL

23. Asteroids families
Tholen classification
(source Wikipedia http://en.wikipedia.org/wiki/Asteroid_spectral_types)
253 Mathilde
433 Eros
21 Lutetia
Tuesday, November 12 2013
23
Dr Harold Clenet, EPSL, EPFL

24. Asteroids families
Carbonaceous chondrite
(enriched in C + O)
Asteroid from C-group
Links to meteorites
Mesosiderite and pallasite
(silicates and iron)
Asteroids from S-group
Iron meteorites
Asteroids from M-group
Tuesday, November 12 2013
24
Dr Harold Clenet, EPSL, EPFL

25. Asteroids families
Carbonaceous chondrite
(enriched in C + O)
Asteroid from C-group
Links to meteorites
Mesosiderite and pallasite
(silicates and iron)
Asteroids from S-group
Iron meteorites
Asteroids from M-group
Tuesday, November 12 2013
25
Dr Harold Clenet, EPSL, EPFL

26. Asteroids families
Tuesday, November 12 2013
26
Dr Harold Clenet, EPSL, EPFL

27. Some physical properties
25143 Itokawa
̴ 600 x 300 m
4 Vesta
̴ 500 km diameter
Tuesday, November 12 2013
27
Dr Harold Clenet, EPSL, EPFL

28. Some physical properties
Tuesday, November 12 2013
28
Dr Harold Clenet, EPSL, EPFL

29. Some physical properties
Ida and its moon Dactyl
Tuesday, November 12 2013
29
Dr Harold Clenet, EPSL, EPFL

30. Outline
•
•
Diversity among the asteroids
• The electromagnetic spectrum and asteroids characteristics
• Asteroids families
• Some physical properties
•
Tuesday, November 12 2013
Where do the asteroids come from?
• At the beginning of our Solar System
• From planetesimals to planetary embryos… and asteroids
• Detection of asteroids
Asteroids and society
• Asteroids as hazards
• Asteroids as resources
30
Dr Harold Clenet, EPSL, EPFL

31. Asteroids as hazard
Mercury
The Moon
Tuesday, November 12 2013
31
Dr Harold Clenet, EPSL, EPFL

32. Asteroids as hazard
65 My ago, end of dinosaurs…
Gravity map
Tuesday, November 12 2013
32
Dr Harold Clenet, EPSL, EPFL

33. Asteroids as hazard
Tuesday, November 12 2013
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Dr Harold Clenet, EPSL, EPFL

34. Asteroids as hazard
Tunguska (Siberia), 1908
Peekskill (New York), 1992
Tuesday, November 12 2013
34
Dr Harold Clenet, EPSL, EPFL

35. Asteroids as hazard
The Tcheliabinsk event
Tuesday, November 12 2013
35
Dr Harold Clenet, EPSL, EPFL

36. Asteroids as hazard
Potentially Hazardous Asteroids (PHAs)
> 1400 as early 2013
Tuesday, November 12 2013
36
Dr Harold Clenet, EPSL, EPFL

37. Asteroids as resources
Orion approaching robotic asteroid capture vehicle
Tuesday, November 12 2013
37
Dr Harold Clenet, EPSL, EPFL

38. Asteroids as resources
Phoebe
Orion approaching robotic asteroid capture vehicle
Tuesday, November 12 2013
38
Dr Harold Clenet, EPSL, EPFL

39. Asteroids as resources
Economic factors
•
•
•
Resources (metal/water)
Costs of the mission
Timing
Orion approaching robotic asteroid capture vehicle
YOU?
Tuesday, November 12 2013
39
Dr Harold Clenet, EPSL, EPFL