Bolide impact

Question 1

What sthe avg per day tonnage of mateiral from space?

Answer 1

45

Question 2

What is the typicaly size of mateiral earth recicves from space everyday?

Answer 2

Very small particles about the size of a grain of sand

Question 3

What is a bolide?

Answer 3

asteroid or comet that can create a crater or burn up in the atmosphere

Question 4

What are the different types of bolide?

Answer 4

Asteroid
Comet
Meteroid
Meteor
Meteorite

Question 5

What is an asteroid?

Answer 5

Inactive rocky body oribiting the sun
Diameter between 1m to 900km
May be balls of rubble held togther by weak gravitational field

Question 6

What are comets?

Answer 6

Rocky ice body uptp 50km across
Ice can vapourise in sunlight forming coma (atmopshere) and sometimes a tail of fust, gas and ions

Question 7

What is a meteoroid?

Answer 7

Small piece from a comet or asteroid orbiting the sun
Up to 1m

MOst formed in early solar system

Question 8

What is a meteor?

Answer 8

Light phenomena when a meteoroid enets earths atmosphere and vaporises

shooting star

Question 9

What is a meteorite?

Answer 9

Meteoroid or small astroid fragment (rare) that survived passage through the atmopshere and impacted the surface

Question 10

When did political interest in bolides begin?

Answer 10

1994 when 21 fragments of comet struck jupiter (energy of 1 billion Hiroshima bombs)

started programs to monitor near earth objects

Question 11

Why is the impact of bolides so devestating?

Answer 11

Escape velocity of earth is 11 km/s so this is terminal velocity/ minimal speed but already travelling fast so impact velocity increased

Question 12

What are the 2 types of asteroid?

Answer 12

Stony (similar to mantle)
Nickel-iron (like core)

Question 13

Where are most asteroids located?

Answer 13

Asteroid belt between mars and jupiter

Question 14

What is the range of impacts velocities for asteroids?

Answer 14

11 km/s - 25 km/s

Question 15

What are near earth obects?

Answer 15

Perihelion (closest sun approach) of 1.3 astronomical unit or less

1 AU = distance between earth and sun

Question 16

How many near of asteriods have been discovered?

Answer 16

36,000
~850 1km + (probem is these all found but smaller ones not known about)

Question 17

What is the difference between NEAs (near earth asteroids) and PHAs ( potentially hazardous asteroids)?

Answer 17

PHAs larger at 140m +
If asteriod orbit is less then 0.05 AU MOID or 20 lunar distances

MOID = minimum orbit intersection

Question 18

What is the chnace of impact from PHAs?

Answer 18

1:75000 if earths orbit is intersected

Question 19

How is risk catergorised for bolide impact?

Answer 19

Torino scale

Question 20

What are the catergories on the Torino scale?

Answer 20

0-10
0 = none
1 = normal (predictable orbit - small chance)
2,3,4 = high priority (close approach once every few decades)
5,6,7 = extreme priority (threatening event - regional/ global devestation)
8,9,10 = Certain collision

Question 21

What was the process of downgrading Apophis?

Answer 21

When reported 1 in 300 in 2029
Later same day estimetd 1 in 62
Later same year accurate calculation showed no hit but in 0.1 lunar distance

Question 22

What is the relationship between frequency of impact and impactor size?

Answer 22

Larger impactor less frequent

Question 23

What are airburts?

Answer 23

Bolides with diameter less than 50m that become so hot they explode

Question 24

Over what size will an airbust pose a surface hazard?

Answer 24

~200 kilotons

Question 25

What was the Ural airburst and its effect?

Answer 25

2013 1 in 50 yr event (22 hiroshima bombs) Exploded close to city knocking out electronic networks and shattered windows causing injury ## Footnote No fatalities

Question 26

What were the effects of Tunguska 1908?

Answer 26

Flattened trees in area equivalent to greater London ## Footnote Remote area little loss but in city could kill millions

Question 27

What type of bolide may penetrate atmopsher and impact the surface?

Answer 27

Larger or denser (e.g. iron meteorites)

Question 28

Why cant impacts craters be used to show areas at risk?

Answer 28

Geographic sampling bias towards europe and North america

Question 29

How are impact craters made?

Answer 29

Imppact shockwave which melts material, earth then rebounds and settles forming pattern strucue dependent on size

Question 30

What are the possible environmental impacts of a 1km impact?

Answer 30

Impact winter - dust, soot and aerosols (months to years) Ultraviolet spring - UV flux higher than normal due to ozone depletion

Question 31

What would the human impacts from a major bolide be?

Answer 31

Effect of climatic disturbance on food production - developed countries only havr sufficient food supply for 1-2 months

Question 32

What is the impact of asteroids which are >10km across?

Answer 32

Mass extinction

Question 33

What were the effects of K-Pg?

Answer 33

75% all species wiped out Intense infra-red pulse - wildfires Dust blocked sunlight 10-20% reduced up to 10 years Emissions from wildfires and remaining co2 produced longer period of global warming

Question 34

When is deflection of a bolide possible?

Answer 34

Diameter of a km with warning of 10 years or so

Question 35

What problem is associted with trying to deflect bolides?

Answer 35

Might defect them so that it does hit

Question 36

What are some problems asscoited with deflection methods?

Answer 36

All untested Fragmentation - migh lead to more unpreditable fall

Question 37

What are short period comets?

Answer 37

orbital period less then 200 years (Kuiper belt beyond neptune) Return to inner solar system at predictable intervals

Question 38

What are long period comets?

Answer 38

Potentially from hypithesised Oort cloud and visit inner solar system at interval longer then 200 years

Question 39

WHy might long period comets be so big?

Answer 39

as have undergine little attrition from repeat passes close to sun