1. What’s New on the Planets?

2. Small Bodies of the Solar System
Asteroids: within the orbit of Jupiter
Centaurs: Between Jupiter and Neptune
Kuiper Belt Objects (KBO’s): Beyond Neptune
Scattered Disk: Extreme KBO’s
Comets: Icy bodies with elongated orbits
Meteoroids: Small objects
Meteors: vaporize in Earth’s atmosphere
Meteorites: survive to reach surface

3. The Asteroid Belt, 2001

4. The Asteroid Belt, 2010

5. Asteroid Discoveries Asteroids Year 1 1801 100 1867 500 1902 1,000
1921
2,000
1942
5,000
1972
10,000
1981
20,000
1993
50,000
1999
100,000
2000
200,000
2003

6. Recent Progress 2010 September 2 2013 February 1
Minor planets catalogued
Officially numbered
Named
2013 February 1
Minor planets catalogued
Officially numbered
Named

8. Can we predict impacts? Incomplete inventory of objects
May be a million km-sized objects
Initial observations don't permit completely accurate predictions
Comets vent gases and change orbits
The meaning of probability of impact
Planets don’t “wander”
Observational uncertainty

9. Example, Measuring A Lot
You measure the lot 5 times, getting 99.7, 99.9, 100.1, and feet.
Average = 100
Best estimate but might not be true value
Any random measurement has even odds of being too high or low
P All 5 too high or low = (1/2)5 = 1/32
P 4 too high or low = 5/32
P 3 too high or low = (5*4/2)/32 = 10/32

10. Impact Probability

11. Impact Probability

12. Meteorite Peekskill, NY 1992

13. Chondrite

14. Stony-Iron Meteorite

15. Iron Meteorite

16. Meteo-Wrongs Meteorites Never:
Have internal cavities
Have layers
Have veins
Flatten on impact
Mold around objects
Almost never light in color outside
If you “think” it’s magnetic, it’s not magnetic

17. Nope

18. Nope

19. Uh-uh

20. No Way

21. Nope

22. Nope

23. Nope

24. Tunguska, 1908

25. Tunguska, 1908

26. Sikhote-Alin Fall, February 12, 1947 Mass = 100,000 Kg

27. Sikhote-Alin Crater

28. Sikhote-Alin Crater

29. Sikhote-Alin Crater

30. Near Miss, August 10, 1972

31. 1972 Near Miss Object was about the size of a bus
Entered Atmosphere over Utah, travelling north, exited over Canada
Velocity 15 km/sec
Missed by 58 km

32. Returning to Space

33. Carangas, Peru, 2007

34. Carangas, Peru, 2007

35. Averting Impact Hazards
Simplest Strategy: Detection + Diversion
Destruction too unpredictable
Can object be destroyed?
“Cookie crumbs have no calories”
In real life, the pieces matter
The longer the lead time, the easier diversion becomes
Only need a close miss
Detection is cheap and off-the shelf

36. Diversion
“The question is: how to do it? These things must be done … delicately.”
Nukes?
Thrusters?
Space tug?
Gravitational?
Solar Sail
Laser?

37. Asteroid Itokawa

38. Space Tug

39. What is a Planet? Ancient: 7 (including sun and moon)
Copernicus: Sun and moon out, Earth in (6)
Uranus, 1781 (7)
Ceres 1801 (8); 12 by 1850
Asteroids Out, back to 7
Neptune 1846 (8) Pluto 1930 (9)
Kuiper Belt, 1990’s; Pluto out
This is not over yet.

40. What is a Planet? Current Definition:
Hydrostatic Equilibrium
Clears its vicinity
Will certainly need adjustment in the future

41. Hydrostatic Equilibrium

42. Hydrostatic Equilibrium

43. Clearing the Vicinity

44. Two Coming Comets PANSTARRS ISON
Comets are like cats; they have tails, and they do precisely what they want. –David Levy
PANSTARRS
March-April 2013
Near Moon on March 12
Faintly visible to unaided eye?
ISON
800,000 miles from Sun in November 2013
May be very bright in December
January 8, 2014, only 2° from Polaris

45. Ceres and Vesta

46. Dawn to Vesta and Ceres First Mission to use ion propulsion
First Mission to main belt asteroids
First Mission to orbit two different bodies

47. Getting There

49. Vesta’s Huge Crater

50. Rocket Science

51. Dropping the Heat Shield

52. Curiosity Landing

53. Where Things Landed

54. Mount Sharp

55. Layeerd Rocks

56. Conglomerate

57. Layered Rocks

58. Self Portrait

59. Drill Holes

60. Meteorite from Mercury?

61. Finding Other Solar Systems

62. The Sample Bias Problem

63. The Exoplanet Zoo Hot Jupiters Highly eccentric orbits Super-Earths
Must have migrated inward
Highly eccentric orbits
Super-Earths
Waterworlds?
861 as of February 19, 2013

64. Kepler Monitor 100,000 stars continuously for 4+ years
Views an area about 10 degrees across
Detects transits
Star dims by 1/10,000