1. Back-Projecting Secondary Martian Craters Using a Cone of Uncertainty
GEOG 596A Proposal, Spring
Tim Naegeli

2. Agenda Background Objectives Study Areas Data & Software Workflow
Anticipated Results

3. Background
In absence of samples, cratering is the only way to determine the age of a surface

4. Background
Laura, J., Skinner Jr, J.A., and Hunter, M.A. (2017) Large Crater Clustering Tool. Computers and Geosciences (submission).

5. Characteristics of Secondary Craters
Background
Characteristics of Secondary Craters
Pattern
Size
Depth
Shape

6. Background

7. Background

8. Background

9. Objectives
The purpose of this project is to determine an effective method to back-project secondary craters on Mars to determine the primary crater that created them.

10. Study Areas

11. Study Areas Zunil 10.1 kilometer diameter Primary crater
Secondaries occurring in obvious rays
“Control” for the project

12. Study Areas Lyot 222 kilometer diameter Primary crater
Older area than Zunil, no obvious rays
Robbins and Hynek (2011) identified secondaries up to 5,200 kilometers away from Lyot

13. Study Areas Bonneville 210 meter diameter Visited by Spirit in 2004
Like a secondary due to size and depth
Unknown primary source

14. Software & Data ArcMap THEMIS CTX HiRISE Mars Odyssey
100m IR, 18m VIS spatial resolution
2002 – Today
Planet wide coverage
CTX
Mars Reconnaissance Orbiter
8 m spatial resolution
2006 – Today
“Regional” coverage
HiRISE
25 cm spatial resolution
“Local” coverage

15. Workflow

16. Workflow

17. Workflow Crater characteristics are captured… …then categorized
Diameter Ellipticity (1 – Dminor/Dmajor)

18. Workflow

19. Workflow See how many line back-projections intersected with Zunil
By diameter and ellipticity
See how many cone back-projections intersected with Zunil
Compare line and cone results
At what cone size do the amount of intersections significantly improve (for each diameter and ellipticity)
Record “final” back-projection parameters

20. Workflow Part 2 – Lyot Part 3 – Bonneville
Process is essentially the same as Zunil, except start with the information learned at Zunil
Only go through combinations again if no progress shown
Part 3 – Bonneville
Digitize Bonneville
Create 3,000 km buffer
Digitize all craters with 20x Bonneville’s diameter
Find intersection(s)
Identify most likely source

21. Anticipated Results
Cone of uncertainty offers significant improvement over line
Each crater system and type will present new challenges, but generally there should be a way to identify the cone
More work needed
Other systems
Potential multiple sources?

22. Thank you!