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
Becquerel Crater, NASA/JPL/MSSS QUESTION of HABITABILITY – FOLLOW the WATER On Earth – Life Needs Water. Evidence for Ancient Life Typically Found in Water-Deposited Sedimentary Rocks. Sedimentary Rocks Typically are Layered. Numerous Outcrops of Layered Rocks Have Been Found on Mars (MOC images).
NASA/JPL GOOD BAD WORST HABITABILITY Problem: ALL Sediments are Layered But - NOT All Layered Rocks are Sedimentary 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 UNCERTAINTY - Which Location with Layered Rocks to Choose for the MSL Mission?
The Question of Habitability – Not Just Where H2O – 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: - (1) Layered Rocks Deposited in an Aqueous Environment - (2) Rocks from Early in Mars History (Noachian) 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 If even the Meridiani sediments are not clear cut sediments to everyone, is it possible to find any place where aqueous deposition can not be questioned? Fortunately – there is.
The Smoking Gun: Eberswalde Deltaic Complex • persistent fluvial activity • extended time periods of rainfall • into standing body of water • definitely deposited by flowing water • No plausible alternative scenario
Meandering Channels prime evidence for on-going, persistent flow of water Channels record complex history of migration, avulsion and bifurcation
Multiple Delta Lobes • up to 150 m of sediment • 6-30 km3 sediment vol. • minimum duration estimates, 10’s to 100’s of years (Jerolmack et al., Lewis & Aharonson) • by comparison to terrestrial analogs, sedimentary record more likely ranges from 150, 000 years to several million years (Bhattacharya et al.)
Eberswalde within Latitudinal and Elevation Constraints for MSL, Overall Slopes Gentle (< 10 deg.)Dickson et al. next talk SO, WHERE to LAND ?
With a minimal drive-to capability of 20 km, the logical place would be # 2 Yet, topography is rough in comparison with e.g. the MER-B landing site A more realistic ellipse (20 x 3 km) can be placed across “smoother” portions of Eberswalde Crater
Yet, in close-up even those areas have roughness due to eroded bedrock surfaces (MOC R13-02140, 3 km wide) 500 m
500 m Yet, in close-up even those areas have roughness due to eroded bedrock surfaces (MOC R06-00324, 3 km wide)
At site # 1 or vicinity a 20x3 km ellipse could probably be fitted onto pretty smooth terrain, but we would have to drive about 40 km to get to the delta complex NOT within MSL specs, BUT….. Because of the widespread bedrock erosion it is likely that there would be plenty of interesting and most likely sedimentary bed rock outcrops along a drive towards the Delta With MRO observations over the # 1 to Delta traverse, a route of interesting outcrops could be chosen. Most likely Noachian sediments, water deposited in part? 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 of the Eberswalde Delta complex.
+ + + 3 km
Studying Eberswalde will require either a long drive or landing in rough terrain, but the scientific payback would be tremendous • Goodies for Everyone: For the Sedimentologists • Sedimentary Rocks, aqueous environment. Rainfall & sustained flow. Soil and clay formation? • Standing Body of Water, accumulation of fines likely. • Heterolithic Succession, softer intervals mudstones? • Point bar and deltaic shallowing upwards successions? Types & associations of sedimentary features? Prodelta mudstones? • Microbial mats in sandy/muddy deposits on delta platform? 100 m
Studying Eberswalde will require either a long drive or landing in rough terrain, but the scientific payback would be tremendous • Goodies for Everyone:For the Exobiologist • Aqueous environment • Standing Body of Water • Noachian in Age • If life was present, remains should have been buried in prodelta deposits • Good preservation of organic matter & biomarkers because of rapid burial in prodelta muds? • Potential for preserving microbial mats in sandy and muddy deposits on delta platform?