1. Using Boulder Diameter- Crater Diameter Ratios to Differentiate Primary from Secondary Craters on the Lunar Surface Cody Carroll, Ally Fess, and Hannah Adams Kickapoo High School April 1 st, 2011

2. Purpose of Research To distinguish primary craters from secondary craters on the lunar surface using qualitative and quantitative properties.

3. Study Area: Southeastern Mare Imbrium Pytheas Lambert Euler Between latitudes: 10°N-30°N and longitudes: 20°W-40°W

4. The Formation of Secondary Craters

5. Significance of Study Being able to differentiate between primary and secondary craters enables a more accurate method of relative dating of the lunar surface. Being able to differentiate between primary and secondary craters enables a more accurate method of relative dating of the lunar surface.

6. Secondary craters, due to the trajectory angles from the primary impact site, should demonstrate a more eccentric shape than primary craters. “Ballistics of the Copernican Ray System,” E.M. Shoemaker Secondary craters should have asymmetrical ejecta rays of varying length distributed unevenly around the crater rim.

7. Ruler set in scale of pixels Secondary craters should demonstrate a larger ratio of boulder-diameter/ crater-diameter than primary craters. Conversion factor of:.513m/pixel R= B d /C d

8. M137699035LE Boulders of secondary craters should be chaotically distributed and oriented to the downrange region of the crater.

9. M142421418LE (lower) M142394256LE M144857093RE (bottom) M144870473LE (upper) Secondary Primary

10. M144856909LE (lower) M137699035LE (upper) M142421418LE (upper) M144870473LE (near center) Secondary Primary

11. Quantitative Data Primary Crater Results Image Number Diameter (m) Average Boulder Diameter (m) Ratio of Crater to Boulder M142394256LE4101.8460.0045 M142421418LE (1)651.5112.3020.018 M144856909LE (2)8006.41250.008 M144870473LE (1)461.75.84820.01266 M144870473LE (3)220.593.84750.01744 M144857093RE605.345.89950.009745

12. Quantitative Data Secondary Crater Results Image Number Diameter (m) Average Boulder Diameter (m) Ratio of Crater to Boulder M137699035LE (1)117.992.9750.0252 M137699035LE (2)292.416.1580.0215 M142421418LE (2)123.123.2490.0302 M144856909LE (1)548.9139.5010.0719 M144856909LE (2)51310.260.02 M144870473LE (2)1434.89360.03 M144857093LE (1)107.732.9490.027 M144857093RE104.6525.8920.0558

13. Analysis of Primary Craters (Diameter, Avg. Boulder size, Bd/Cd ratios)

14. Analysis of Secondary Craters (Diameter, Avg. Boulder size, Bd/Cd ratios)

15. Comparison of Primary to Secondary Boulder-diameter/ Crater-diameter Ratios Primary Crater- Bd/Cd ratio Distant Secondary Crater- Bd/Cd ratio *Proximal crater

16. M144856909LE Differentiating Ejecta Materials

17. Conclusions Secondary craters, due to the trajectory angles from the primary impact site, did demonstrate a more eccentric shape than primary craters. No correlation was observed between secondary craters and asymmetrical ejecta rays of varying length distributed unevenly around the crater rim. Secondary craters did demonstrate a larger ratio (.02 and above) of boulder-size/ crater-size than primary craters. Boulders of secondary craters were unevenly distributed and oriented to the downrange region of the crater (within the crater rim or within 60m outside of downrange rim).

18. References Bart, Gwendolyn D. and Melosh, H.J. (2007). Using Lunar Boulders to distinguish primary from distant secondary craters. Geophysical Research Letters, Volume 34, L07203. pgs. 1-5 Shoemaker, E.M. (1960). Ballistics of the Copernican Ray System. Proceedings of Lunar and Planetary Exploratorium Colloquim, Volume 2 Number 2, pgs. 7-20. McEwen, Alfred S., Preblich, Brandon S., Turtle, Elizabeth P., Artemieva, Natalia A. and many others. (2005). The rayed crater Zunil and interpretations of small impact craters on Mars. Retrieved from http://www.sciencedirect.comhttp://www.sciencedirect.com

19. Acknowledgements Mr. Andrew Shaner –For his providing of Adobe Photoshop for crater/ lunar boulder analysis Dr. Georgiana Kramer – for her student mentoring on scientific analysis and conversion of pixel size to distance on imagery Mr. Lynn Coffey –For his assistance in formatting of graphical analysis of data