asteroids: what, where, how and why we...

Asteroids: What, where, how and why we care?

Dr. Harold Geller George Mason University

30 June 2016

1

What is an Asteroid?

2

3

4

Asteroid Sizes

5

Where are they? &

Where do they come from?

6

7

1

1

2

3 4

8

How do we study asteroids?

9

LINEAR NEO Search Systems

10

Asteroids: Years of Discovery

1

11

Hubble!

12

Galileo Spacecraft

13

NEAR Shoemaker

14

EROS Asteroid 433

15

16

17

Hayabusa Visiting Asteroid Itokawa

18

Hayabusa Visiting Asteroid Itokawa

19

Why do we care?

20

21

22

What happens if an Asteroid hits

the Earth?

23

?

24

25

26

27

Meteor Crater, Arizona

28

Earth Sterilizing Impact

Mass Extinction Impact

Civilization Threatening Impact

29

What Happens When an Impact Takes Place?

Bolides (up to 5 MT) • Great fireworks display, no damage Tunguska-class (15 MT) impact • Damage similar to large nuclear bomb (city-killer) • Average interval for whole Earth: 100 yr. • Minor risk relative to other natural disasters

(earthquakes, etc.) Larger local or regional catastrophes (e. g. 10,000

MT) • Destroys area equivalent to small country • Average interval for whole Earth: 100,000 yr. • Moderate risk relative to other natural disasters Global catastrophe (> 1 million MT) • Global environmental damage, threatening civilization • Average interval for whole Earth: 1 million years • Major risk relative to other natural disasters

30

Could it happen to us?

31

32

33

Terrestrial Impact Frequency year

century

million yr.

billion yr.

ten thousand yr.

100 million million 10,000 100 1 0.01

Hiroshima

Tunguska

K/T

TNT equivalent yield (MT)

Global catastrophe

Tsunami danger

34

What Can We Do?

35

Strategies

• Detect Project NEO (Near Earth Objects) http://neo.jpl.nasa.gov/ • Deflect Gravitational Tractor Impactor • Destroy

36

LINEAR NEO Search Systems

37

38

39

Civilization Threatening Impact

40

Mass Extinction Impact

41

Earth Sterilizing Impact

42

Known Kilometer- Size Near Earth Asteroids

1000

500

1990 1995 2000

estimated total NEAs > 1 km

Spaceguard official start

43

44

45

46

47

48

Looks like a potato?

49

50

51

52

53

Questions??

54