# Presentation: 177770

## 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

## REGIONAL SETTING

- 150 km

## LOCAL SETTING

- 50 km

## 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

## THEMIS NIGHT IR MOSAIC

- 25 km

## 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.

## AGE OF HOLDEN CRATER

- 50 km

## ALLUVIAL FANS

- 15 km

## ALLUVIAL FANS

- 10 km

## ALLUVIAL FANS

- Fan is 13 km across

## ALLUVIAL FANS

- MOC E1600970
- 2.87 km across

## UZBOI VALLIS DEPOSIT

- 5 km

## LANDING AREA

- Zone is 20 km across

## AREA OF INTEREST: 2 RADII

- Zone is 20 km across

## 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*****(8*****gS/f*****)****0.5**** **
***ρ******s****** ***is sediment density, ***ρ******w*** is fluid density, ***g*** is gravitational acceleration

- 1 km

## LAYERED DEPOSITS

- 2.89 km across

- MOC M0302733
- 2.87 km across

## LIGHT-TONED LAYERED DEPOSITS

- MOC E0102248
- 3.52 km across

## LIGHT-TONED LAYERED DEPOSITS

- MOC E0102248
- 3.52 km across

## LANDING AREA

- MOC E0500667
- 2.86 km across

## ENGINEERING REQUIREMENTS

| Engineering
Parameter |  | Requirement | Observations | Notes |
| --- | --- | --- | --- | --- |
| Latitude |  | 60°N to 60°S | 26.4°S |  |
| Altitude  |  | ≤ 2000 m | –2230 to –2330 | MOLA-derived elevation |
| Landing ellipse radius |  | ≤ 10 km | 10 km | Excluding uncontrolled wind effects during parachute descent |
| Slopes | 2 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 degrees | HRSC | Radar processing – spoofing |
|  | 5 m length scale | ≤ 15 degrees | MOC or HiRISE stereo DEMs? | Rover tilting
Trafficability in loose granular material |
| Rock height |  | ≤ 0.6 m | HiRISE (flows likely unable to move this size) | Probability that a rock higher than 0.6 m occurs in a random sampled area of 4 m2 should be less than 0.25%.
Suggests low to moderate rock abundance |
| Winds | Steady state horizontal | ≤ 30 m/s | Models | At altitudes of 0 to 10 km above  the surface |
|  | Steady state vertical | ≤ 10 m/s | Models | At altitudes of 0 to 10 km above  the surface |
| Wind gusts |  | Evaluate case by case | Models | At altitudes of 0 to 10 km above  the surface |
| Radar reflectivity |  | Ka band reflective | Radar data | Adequate Ka band radar backscatter cross-section (>-20 db) |
| Load bearing surface |  | Not dominated by dust | TI 288–504, albedo low | Thermal inertia >100 J m-2 s-0.5 K-1 and albedo <0.25; radar reflectivity >0.01 for load bearing bulk density |

## GUSEV CRATER

- 25 km

## GUSEV CRATER

- From *Irwin* (2003), 4th MER landing site meeting

## GALE CRATER

- 20 km

## 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.