1. AQUEOUS SEDIMENTARY DEPOSITS IN HOLDEN CRATER: LANDING SITE FOR THE MARS SCIENCE LABORATORY Rossman P. Irwin III and John A. Grant Smithsonian Institution, National Air and Space Museum

2. REGIONAL SETTING 150 km

3. LOCAL SETTING 50 km

4. THEMIS DAY IR WITH MOLA Most of the dissection and deposits are on the high- relief western crater rim. Note the low- thermal- inertia region in the crater center, contrast with outlying floor surfaces. 25 km

5. THEMIS NIGHT IR MOSAIC 25 km

6. HOLDEN CRATER: JUSTIFICATION Alluvial fans: weathering and transport processes, discharge and runoff production rates inferred from sedimentary load and structures. Light-toned layered deposits: composition, origin, environmental implications. Habitability? Paleoclimate of the Late Noachian to Early Hesperian transition. Discharge from an exterior drainage network. Relatively safe landing zone bordering areas of interest within range of the rover. Impact ejecta from 2.5 km crater in landing zone. HOLDEN CRATER: JUSTIFICATION

7. AGE OF HOLDEN CRATER 50 km

8. ALLUVIAL FANS 15 km

9. ALLUVIAL FANS 10 km

10. ALLUVIAL FANS Fan is 13 km across

11. ALLUVIAL FANS MOC E1600970 2.87 km across

12. UZBOI VALLIS DEPOSIT 5 km

13. LANDING AREA Zone is 20 km across

14. AREA OF INTEREST: 2 RADII Zone is 20 km across

15. HYDROLOGY Calculate critical shear stress for entrainment τ c given largest sediment grain diameter D: τ c = 0.06(ρ s  ρ w )gD Solve for flow depth H at that shear stress given measured slope S: τ = ρ w gHS Solve for discharge Q given channel width W: Q = HWV = H 1.5 W(8gS/f) 0.5 ρ s is sediment density, ρ w is fluid density, g is gravitational acceleration 1 km

16. MOC E0401686 2.89 km across LAYERED DEPOSITS MOC M0302733 2.87 km across

17. MOC E0102248 3.52 km across LIGHT-TONED LAYERED DEPOSITS

18. MOC E0102248 3.52 km across LIGHT-TONED LAYERED DEPOSITS

19. LANDING AREA MOC E0500667 2.86 km across

20. ENGINEERING REQUIREMENTS Engineering Parameter RequirementObservationsNotes Latitude60°N to 60°S26.4°S Altitude≤ 2000 m–2230 to –2330MOLA-derived elevation Landing ellipse radius≤ 10 km10 kmExcluding uncontrolled wind effects during parachute descent Slopes2 to 5 km length scale ≤ 3 degrees<1° in landing area Radar altimetry errors to start powered descent 20 to 40 m length scale ≤ 15 degreesHRSCRadar processing – spoofing 5 m length scale ≤ 15 degreesMOC or HiRISE stereo DEMs? Rover tilting Trafficability in loose granular material Rock height≤ 0.6 mHiRISE (flows likely unable to move this size) Probability that a rock higher than 0.6 m occurs in a random sampled area of 4 m 2 should be less than 0.25%. Suggests low to moderate rock abundance WindsSteady state horizontal ≤ 30 m/sModelsAt altitudes of 0 to 10 km above the surface Steady state vertical ≤ 10 m/sModelsAt altitudes of 0 to 10 km above the surface Wind gustsEvaluate case by case ModelsAt altitudes of 0 to 10 km above the surface Radar reflectivityKa band reflective Radar dataAdequate Ka band radar backscatter cross-section (>-20 db) Load bearing surfaceNot dominated by dust TI 288–504, albedo low Thermal inertia >100 J m -2 s -0.5 K -1 and albedo 0.01 for load bearing bulk density

21. GUSEV CRATER 25 km

22. GUSEV CRATER From Irwin (2003), 4 th MER landing site meeting

23. 20 km GALE CRATER

24. WHY HOLDEN? Alluvial fans are among the most compelling fluvial landforms on Mars. The segmentation, fan- head trenches, frontal scarps, and contributing alcoves in Holden are better developed and more complex than at any other site on Mars. No region is more heavily dissected than Margaritifer Sinus. The Late Noachian to Early Hesperian transition was arguably the most important time in Martian geologic history for fluvial activity. Sediment was delivered to this terminal basin from both inside and outside the crater. Both quiescent and dynamic deposits available.