Impacts

Question 1

What is the role of impact cratering in Earth’s History?

Answer 1

• formation of the Moon
• extinction events

Question 2

stages of impact cratering

Answer 2

1. compression
2. excavation
3. modification

Question 3

TRUE or FALSE: the bolide (impactor) is typically vaporized in the impact event

Answer 3

TRUE

Question 4

compression stage

Answer 4

• shock wave expands out from point of impact
• compresses rock to 1/3 its usual volume
• rock can flow like a fluid

Question 5

excavation stage

Answer 5

• decompression wave follows shock wave
• target rock and bolide (vaporize) flow -> SPRAY OUT OF TRANSIENT CAVITY
• EJECTA travels out as a conical sheet
• crater rim overturned

Question 6

modification stage

Answer 6

• typical for large structures
• gravity unable to sustain the cavity
• slumping of crater walls
• central uplift

Question 7

What are 4 features of the impact cratering process?

Answer 7

1. impact melt sheet
2. breccia
3. tektites
4. ejecta rays, secondary craters

Question 8

How many impact craters are recorded in Earth’s crust?

Answer 8

~200

Question 9

During which geological period did the Chicxulub impact occur?

Answer 9

Cretaceous-Paleogene

Question 10

How large is the Chicxulub crater

Answer 10

180 km diameter

Question 11

How often do impact extinction events occur?

Answer 11

every 10s of million years

Question 12

TRUE or FALSE: a pandemic is considered an anthropogenic hazard.

Answer 12

FALSE –> pandemic = non-anthropogenic

Question 13

What is the 2022 Doomsday Clock Statement

Answer 13

It is 100 seconds to midnight.

Question 14

Rank the following major threats (hazards):
- climate changes
- pandemic
- disruptive tech in the age of disinformation
- nuclear security

Answer 14

1. nuclear security
2. climate change
3. pandemic
4. disruptive tech in the age of disinformation

Question 15

what can we do to mitigate the risk of impact?

Answer 15

1. observe (identify PHAs and determine their orbit)
2. plan
3. prepare (develop technology to deflect a PHA)

Question 16

What is the DART mission? target? purpose? was it successful?

Answer 16

• Double Asteroid Redirect Test
• NASA’s first Planetary Defence mission
• target: Didymos and Dimorphos
• purpose: demonstrate that a regionally-destructive asteroid could be deflected by KINETIC IMPACT
• SUCCESSFUL! –> changed orbit of Dimorphos

Question 17

TRUE or FALSE: the probability of an impact by a PHA in the next century is extremely high.

Answer 17

FALSE –> extremely low probability