# Presentation: 063893

## Deltas and related sedimentary deposits:

- A key class of landing sites for the MSL Mission
- J.L. Dickson, C.I. Fassett, J.W. Head, M.A. Kreslavsky,
- J.B. Madeleine and M.I. Ivanov (Brown University)

## MSL Science Objectives

- Primary science objectives for Mars Science Laboratory:
- - Assess the biological potential of at least one target environment.
- - Characterize the geology and geochemistry of the landing region.
- - Investigate planetary processes of relevance to past habitability.

- Deltaic environments offer the greatest
- potential for achieving these objectives
- - Deltas suggest standing bodies of water in the past, increasing the potential for habitability.
- Smooth deposits on crater floors offer ideal locations for landing of MSL and traversing.
-  Here, we propose two separate landing sites that offer the greatest chance to achieve the scientific objectives.
-  Nili Fossae crater lake deposits.
-  Eberswalde crater fan deposits.

## 1. Nili Fossae Crater Lake Deposits

- THEMIS IR Daytime Mosaic
- w/ MOLA Color Topography

## Nili Fossae Crater Fan Deposits

- Two prominent fan deposits found in this 40-km diameter crater at mouths of entering streams.
- Total Area of two fans: ~56 km2.
- Outlet channel implies filled crater lake.

- THEMIS IR Daytime Mosaic
- w/ MOLA Color Topography

##  Influx: Crater Fan Deposits

- Mosaic of MOC images R23/00833 and S04/00725.

## The present minimum elevation of the outlet is higher than almost all of the crater floor, including the fan deposits.
This -2390 contour represents the minimum lake stand (assuming present topography).
Maximum depth of the minimum stand: >300 m.
Sediments also deposited on crater floor from suspension.

- The present minimum elevation of the outlet is higher than almost all of the crater floor, including the fan deposits.
- This -2390 contour represents the minimum lake stand (assuming present topography).
- Maximum depth of the minimum stand: >300 m.
- Sediments also deposited on crater floor from suspension.

## Qualitative Indicators of Persistent Flow

- Mineralogy:  Hydration and clay signatures are observed in OMEGA data within the watershed of the Nili Fossae delta deposits.

- Hydration

- Clay

- Mustard et al., OMEGA team 2005

## 2. Eberswalde Crater Fan Deposits

- Malin and Edgett, 2003
- Moore et al., 2004

- • Similar sedimentary fans and floor deposits.

## Eberswalde Crater

- • 10 km reference traverse (right) demonstrates access to key units.

## Eberswalde Crater - Engineering

**Low Elevation**
- Elevation of floor is
- -1500 m, well below the threshold for landing.
**High Thermal Inertia**
- Lowest values at
- ~400 J/m2K s1/2.
**Low Albedo**
- All values < 0.20.

**Low Slope**
- 99.4% of MOLA point-to-point slopes are below 10°, with the only steep slopes on the margin of the crater.

## Implications of the Nili Fossae Crater Lake and Eberswalde Crater Fan and Floor Deposits

- Persistent surface water was probably required to form the observed deposits.
- Each site has preserved, accessible sedimentary deposits. Date to Late Noachian-Hesperian.
- Terrain surrounding the fan deposits is flat at all measurable baselines, providing a safe location for landing and traverse.
- These sites fall under the category of “fluvio-deltaic and/or lacustrine settings” propsed as “optimal” by *Golombek and Grotzinger* (this conference).
- These types of sites merit further investigation.