THE EBERSWALDE DELTAIC COMPLEX AS A HIGH SCIENCE-RETURN TARGET FOR THE 2009

MARS SCIENCE LABORATORY

Juergen Schieber, Department of Geological Sciences, Indiana University, Bloomington, IN 47405

Ken Edgett, Malin Space Sci. Sys., P.O. Box 910148, San Diego, CA 92191-0148

Michelle Minitti, Center for Meteorite Studies, Arizona State University, Tempe, AZ, 85287-1404

Image Credits: NASA/JPL/MSSS

On EarthOn Earth – Life Needs – Life Needs WaterWater. . Evidence for Ancient Life Typically Found in Evidence for Ancient Life Typically Found in Water-Deposited Water-Deposited Sedimentary RocksSedimentary Rocks..

Sedimentary Rocks Typically are Sedimentary Rocks Typically are LayeredLayered..

Numerous Outcrops of Layered Rocks Have Been Numerous Outcrops of Layered Rocks Have Been Found on Mars (MOC images).Found on Mars (MOC images).

QUESTION of HABITABILITY – FOLLOW the WATERQUESTION of HABITABILITY – FOLLOW the WATER

Becquerel Crater, NASA/JPL/MSSS

Eagle Crater/Meridiani – sulfates, spherules, sand, cross-bedding

MER Team: playa – dune complex, water in pores & at surface

McCollum & Hynek: volcanic ash beds / volcanic surge deposits

Knauth et al.: impact surge deposits

Problem:Problem: ALL Sediments are Layered ALL Sediments are Layered But - NOT All Layered Rocks are Sedimentary But - NOT All Layered Rocks are Sedimentary

NASA/JPL

UNCERTAINTY - UNCERTAINTY - Which Location with LayeredWhich Location with Layered Rocks to Choose for the MSL Mission? Rocks to Choose for the MSL Mission? HABITABILITY

GOOD

BAD

WORST

The Question of HabitabilityThe Question of Habitability – Not Just Where H – Not Just Where H22OO

– But When? – But When?Omega mapping of smectites suggests more water and surficial bodies of water early in Mars history (Bibring et al., Science, v. 312, p. 400, 2006).

Mawrth Vallis smectite-rich outcrops (blue) are of Noachian age (Poulet et al., Nature, v. 438, p. 623-627, 2005)

OPTIMAL LANDING SITE for MSL Science Objectives:OPTIMAL LANDING SITE for MSL Science Objectives:

- - (1)(1) Layered Rocks Deposited in an Aqueous Environment Layered Rocks Deposited in an Aqueous Environment

- - (2)(2) Rocks from Early in Mars History (Noachian) Rocks from Early in Mars History (Noachian)

If even the Meridiani sediments are not clear cut If even the Meridiani sediments are not clear cut sediments to everyone, is it possible to find any sediments to everyone, is it possible to find any place where aqueous deposition can not be place where aqueous deposition can not be questioned? questioned? Fortunately – there is.Fortunately – there is.

The Sediments we know Best: Meridiani

MER Team: playa – dune complex, water in pores & at surface

McCollum & Hynek: volcanic ash beds / volcanic surge deposits

Knauth et al.: impact surge deposits

The Smoking Gun: The Smoking Gun: Eberswalde Deltaic Eberswalde Deltaic ComplexComplex

- persistent fluvialpersistent fluvial activity activity

- extended timeextended time periods of rainfall periods of rainfall

- into standing bodyinto standing body of water of water

- definitely depositeddefinitely deposited by flowing water by flowing water

- No plausibleNo plausible alternative scenario alternative scenario

Meandering ChannelsMeandering Channels prime evidence for prime evidence for on-going, persistent on-going, persistent flow of water flow of water

ChannelsChannels record complex record complex history of migration, history of migration, avulsion and bifurcationavulsion and bifurcation

- Multiple Delta LobesMultiple Delta Lobes - up to 150 m of sedimentup to 150 m of sediment

- 6-30 km6-30 km33 sediment vol. sediment vol. - minimum durationminimum duration estimates, 10’s to 100’s of estimates, 10’s to 100’s of years (Jerolmack et al., years (Jerolmack et al., Lewis & Aharonson) Lewis & Aharonson)

- by comparison toby comparison to terrestrial analogs, terrestrial analogs, sedimentary record more sedimentary record more likely ranges from likely ranges from 150, 000 years to several 150, 000 years to several million years million years (Bhattacharya et al.) (Bhattacharya et al.)

SO, WHERE to LAND ?SO, WHERE to LAND ?Eberswalde within Latitudinal and Eberswalde within Latitudinal and Elevation Constraints for MSL, Elevation Constraints for MSL, Overall Slopes Gentle (< 10 deg.)Overall Slopes Gentle (< 10 deg.) Dickson et al. next talkDickson et al. next talk

With a minimal drive-to With a minimal drive-to capability of 20 km, the capability of 20 km, the logical place would be # 2 logical place would be # 2

Yet, topography is Yet, topography is rough in comparison rough in comparison with e.g. the MER-B with e.g. the MER-B landing sitelanding site

A more realistic A more realistic ellipse ellipse (20 x 3 km)(20 x 3 km) can can be placed across be placed across “smoother” portions “smoother” portions of Eberswalde Craterof Eberswalde Crater

Yet, in close-up even those areas have roughness Yet, in close-up even those areas have roughness due to eroded bedrock surfaces due to eroded bedrock surfaces (MOC R13-02140, 3 km wide)(MOC R13-02140, 3 km wide)

500 m

Yet, in close-up even those areas have roughness Yet, in close-up even those areas have roughness due to eroded bedrock surfaces due to eroded bedrock surfaces (MOC R06-00324, 3 km wide)(MOC R06-00324, 3 km wide)

500 m

At site # 1 or vicinity a 20x3 km At site # 1 or vicinity a 20x3 km ellipse could probably be fitted onto ellipse could probably be fitted onto pretty smooth terrain, but we would pretty smooth terrain, but we would have to drive about 40 km to get to have to drive about 40 km to get to the delta complexthe delta complex

NOT within MSL specs, BUT…..NOT within MSL specs, BUT…..

Because of the widespread bedrock Because of the widespread bedrock erosion it is likely that there would erosion it is likely that there would be plenty of interesting and most be plenty of interesting and most likely sedimentary bed rock outcrops likely sedimentary bed rock outcrops along a drive towards the Deltaalong a drive towards the Delta

With MRO observations over the # 1 to Delta traverse, a route of With MRO observations over the # 1 to Delta traverse, a route of interesting outcrops could be chosen. Most likely Noachian interesting outcrops could be chosen. Most likely Noachian sediments, water deposited in part? sediments, water deposited in part?

If MSL is similarly durable as the MER rovers, it may well be able to If MSL is similarly durable as the MER rovers, it may well be able to make the trip and cap its observations with an in depth examination make the trip and cap its observations with an in depth examination of the Eberswalde Delta complex. of the Eberswalde Delta complex.

LatitudeLatitude LongitudeLongitude Elevation (m)Elevation (m) Landing / DriveLanding / Drive

Ellipse 1Ellipse 1 23.968 S23.968 S 34.442 W34.442 W - 400 to -600- 400 to -600 smoothest, long drivesmoothest, long drive

Ellipse 2Ellipse 2 24.091 S24.091 S 33.325 W33.325 W approx. - 1400 approx. - 1400 ± ± rough, but closerough, but close

Ellipse 3Ellipse 3 23.762 S23.762 S 33.050 W33.050 W - 600 to -700- 600 to -700 ± smooth, long drive± smooth, long drive

3 km

+

++

Studying Eberswalde will require either a long Studying Eberswalde will require either a long drive or landing in rough terrain, but the scientific drive or landing in rough terrain, but the scientific payback would be tremendouspayback would be tremendous

Goodies for Everyone: Goodies for Everyone: For the SedimentologistsFor the Sedimentologists

Sedimentary Rocks, aqueous environment. Rainfall & sustainedSedimentary Rocks, aqueous environment. Rainfall & sustained flow. Soil and clay formation? flow. Soil and clay formation?

Standing Body of Water, accumulation of fines likely.Standing Body of Water, accumulation of fines likely.

Heterolithic Succession, softerHeterolithic Succession, softer intervals mudstones? intervals mudstones?

Point bar and deltaic shallowing Point bar and deltaic shallowing upwards successions? Types & upwards successions? Types & associations of sedimentary associations of sedimentary features? Prodelta mudstones? features? Prodelta mudstones?

Microbial mats in sandy/muddyMicrobial mats in sandy/muddy deposits on delta platform? deposits on delta platform?

100 m

Studying Eberswalde will require either a long Studying Eberswalde will require either a long drive or landing in rough terrain, but the scientific drive or landing in rough terrain, but the scientific payback would be tremendouspayback would be tremendous

Goodies for Everyone:Goodies for Everyone: For the ExobiologistFor the Exobiologist

Aqueous environmentAqueous environment

Standing Body of WaterStanding Body of Water

Noachian in AgeNoachian in Age

If life was present, remains should have been buried inIf life was present, remains should have been buried in prodelta deposits prodelta deposits

Good preservation of organic matter & biomarkersGood preservation of organic matter & biomarkers because of rapid burial in prodelta muds? because of rapid burial in prodelta muds?

Potential for preserving microbial mats in sandy andPotential for preserving microbial mats in sandy and muddy deposits on delta platform? muddy deposits on delta platform?