1. The Gale Crater Mound: A Candidate Landing Site for the 2009 Mars Science Laboratory Jim Bell 1, Ken Edgett 2, Scott Rowland 3, Mike Malin 2 Representing the MSL Mastcam/MAHLI/MARDI Science Team 1 Cornell U.; 2 Malin Space Science Systems; 3 U. Hawaii First MSL Landing Site Workshop May 31, 2006

2. JFB: 5/31/062 Outline Scientific Justification: Why MSL to Gale? Site information Proposed Ellipse and Traverse Options EDL and Trafficability Summary

3. JFB: 5/31/063 Gale Crater Located at 5°S, 137.5°E (222.5°W) in the northeast Aeolis quadrangle, near the highlands/lowlands boundary 140-172 km diameter, named after the Australian eclipse & transit astronomer Walter F. Gale (1865-1945) MOLA Heights (Parker) Plains/Plateau: -1.1 to 0.0 km Floor: -4.5 km; Mound: +0.3 km 5°S 135°E140°E

4. JFB: 5/31/064 Science Case / MSL Relevance Key previous studies: –Viking/Mariner imaging: Scott et al. (1978); Greeley & Guest (1987); Grin & Cabrol (1997); Kuzmin et al. (1998);Cabrol et al. (1999) –and MGS MOC, MOLA: Malin & Edgett (2000, 2001); Edgett & Malin (2001) –and MGS TES; ODY THEMIS: Pelkey & Jakosky (2002); Pelkey et al. (2004) Complementary talk here by N. Bridges

5. JFB: 5/31/065 Gale Crater Highest point exceeds rim by ~1 km Highest point exceeds rim by ~1 km Gale Crater 40-50 km wide central mound

6. JFB: 5/31/066

7. 7 Gale Crater Central Mound Indurated, layered, possibly rocky materials partially covered by dust based on physiography, albedo, and color information Compositional information ambiguous: significant dust & sand cover reduces spectral contrast in currently-available data Distinct layering of outcrops suggests a sedimentary origin, although an igneous origin cannot be ruled out Angular unconformities, filled and exhumed channels, & other buried and exhumed erosional surfaces record significant changes in the depositional and erosional regime of this region regardless of the rock type Interpretation: Apparently, Gale and perhaps much of the surrounding region was completely buried and exhumed, at least once

8. JFB: 5/31/068

9. 9 Unconformity; buried erosional surface (MOC M03-01521) 500 m

10. JFB: 5/31/0610 Evidence for channels cut into the layered rock, then subsequently buried and re- exposed (inverted) (MOC M03-01521)

11. JFB: 5/31/0611 Perspective view of exhumed channel 200 m

12. JFB: 5/31/0612 Gale crater has had a complex history of erosion and deposition (likely sedimentary, but possibly volcanic?) Mound is a remnant of a once-larger deposit that may have filled the entire crater (and more) –The mound consists of hundreds of thin (< 10 m) beds in distinct units of similar thickness and material properties –Partially-exhumed craters (erosional unconformities) in some units indicate significant time between some depositional epochs –Evidence for channels cut into the layered rock, then subsequently buried and re-exposed (inverted) –Evidence for deposition of younger, massive units of light- toned materials at the top of the sequence Science Case / MSL Relevance

13. JFB: 5/31/0613 One Gale history model... (Edgett & Malin, 2000)

14. JFB: 5/31/0614 One Gale history model... (Edgett & Malin, 2000)

15. JFB: 5/31/0615 One Gale history model... (Edgett & Malin, 2000)

16. JFB: 5/31/0616 One Gale history model... (Edgett & Malin, 2000)

17. JFB: 5/31/0617 One Gale history model... (Edgett & Malin, 2000)

18. JFB: 5/31/0618 One Gale history model... (Edgett & Malin, 2000)

19. JFB: 5/31/0619 One Gale history model... (Edgett & Malin, 2000)

20. JFB: 5/31/0620 Chinle Triassic Moenkopi) Kaibab Ls Permian Toroweap Coconino Ss Hermit Sh Muav Ls Cambrian Bright Angle Sh Tapeats Ss Gale captures the essence of the larger, global picture: The mound is a layered, cratered, channeled volume. The story recorded there is rich and complex. The crater itself was filled, buried, then exhumed (at least once, maybe more). Edgett & Malin, 2001)

21. JFB: 5/31/0621 Proposed 20 km Ellipse MOC mosaic, >30 images, 2/06 (Ken Edgett) Ellipse is on a fan of material transported through a valley that cuts/runs down Gale’s wall in the northwest quadrant of the crater N

22. JFB: 5/31/0622 THEMIS-VIS mosaic of all Gale images as of Oct. 2005 Initial version, for THEMIS science team In false color where there is VIS color coverage Ellipse is near 4.6°S, 222.65°W (137.35°E) ellipse near 4.6°S, 22.8°W Bell et al., 2005 20 km

23. JFB: 5/31/0623 5 km

24. JFB: 5/31/0624 THEMIS-VIS V11330001 (7/4/04) 18 m/pixel 16:55 LTST Depositional fan fills about half the ellipse Relatively smooth unit Fan materials were transported through the valley in crater wall (upper left) 5 km

25. JFB: 5/31/0625 EDL and Trafficability/Traverse Edgett considered all possible places for landing ellipse in Gale Crater; Northwest fan ellipse seems like best location Landing might be challenging, but potential landing and traversing hazards appear (initially) no more problematic than at the MER-A site in Gusev Crater... The fan is not the primary scientific goal, but appears to be a safe and interesting place to land Fan could be a possible highlands “grab bag” site (also sampling ancient pre-Gale crust?) for initial scientific investigation; Possible lava on Gale floor, as well. Trafficable routes into the mound identified in MOC images But Gale is not JADPCL: A proposed traverse from the ellipse to the mound would utilize the “Go-to” capabilities of MSL to access to some of the diverse, sedimentary rock section in the mound.

26. JFB: 5/31/0626 Possible Traverse Goal: “Grand Canyon” of the Gale Mound; 500-1000 m of exposed layered sedimentary rock, cross-section of lowest element of Gale stratigraphy; Canyon ~1 to 1.5 km wide. 3 km

27. JFB: 5/31/0627 Summary Gale crater and its central mound of layered sedimentary rock represent an important enigma in our present understanding of Mars –Are the layers sedimentary? If so, how were they transported there? (wind? water?) Why is the central mound so “rhythmically” layered, and higher than the rim/plateau? Outstanding place to test habitability of early Mars We believe that the site meets the EDL, Trafficability, and Planetary Protection requirements of the MSL Project, although the most interesting geological areas will require a drive from a nearby landing site.

28. JFB: 5/31/0628 EXTRAS

29. JFB: 5/31/0629 Gale Crater topography Transverse Mercator contour topo map from the MOLA 128ppd gridded data. (Tim Parker)