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Gully Analysis by the 2009 Mars Science Laboratory

Gully Analysis by the 2009 Mars Science Laboratory. W. E. Dietrich, J. Schieber, B. Hallet, K. S. Edgett and M. C. Malin. Gullies are located at Middle and Polar Latitudes and Might be Key Sites for Recent Water and Habitability Science. There’s a variety of morphologic expressions….

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Gully Analysis by the 2009 Mars Science Laboratory

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  1. Gully Analysis by the 2009 Mars Science Laboratory W. E. Dietrich, J. Schieber, B. Hallet, K. S. Edgett and M. C. Malin

  2. Gullies are located at Middle and Polar Latitudes and Might be Key Sites for Recent Water and Habitability Science

  3. There’s a variety of morphologic expressions… ~3 km across, E16-00043, 41.8°S, 158.0°W

  4. …more examples…

  5. …and more examples.. ~ 3 km wide, S10-00964, 38.0°S, 167.2°W

  6. …and another… • Banked channels • Multiple flow events • Not cratered

  7. They Seem to Be Young • Superimposed craters are uncommon. • Some have dark floors; do not retain dust. • Some cut or superpose eolian bedforms. • Not all are young; some do have superposed craters or eolian bedforms; some have features cut by cracks or faults.

  8. How Do They Form?

  9. Malin/Edgett Still Favor Groundwater Hypothesis • Bolstered by recent excellent evidence that fluids emerged from beneath the ground, rather than by melting of snow. • Key examples include those at which gullies emerge at a fault, suggesting groundwater percolation along fault (image on far right).

  10. Can MSL Go to a Gully Site? D’oh! • We recognize that Planetary Protection likely precludes landing at a gully site, but we feel it is important to have discussed this topic at the 1st Landing Site Workshop. • It is critical to understand that, while MSL theoretically opens up a larger portion of Mars for landing than previous US surface missions, the design still precludes visiting certain key or critical targets.

  11. The Search for Places That a 20 km Diameter Landing Ellipse Will Fit • We examined every gully location known from MOC images, acquired through 30 May 2006, in both hemispheres to 60° latitude. • MSL obviously can’t land on gullied slopes. • MSL likely can’t drive down into craters with gullied walls. • So we sought craters with gullies that are large enough to put a 20 km diameter ellipse on the crater floor, snuggled up as close as possible to gully apron material. • Most craters with gullies are too small for a 20 km ellipse. • Most craters large enough for 20 km ellipse do not have gullies. • We found only 3 viable locations, with two craters at one of the three locations

  12. Candidate 1 & 2: South Terra Cimmeria elevations are ~ +0.4 km White boxes show existing MGS MOC coverage to 30 May 2006. 35.2°S, 203.9°W 35.8°S, 204.4°W

  13. Gullies in Candidate 1 Crater

  14. Floor of Candidate 1 Crater

  15. Candidate 3: Hale Crater (floor too rugged) White boxes show existing MGS MOC coverage to May 2006.

  16. Many, Many Terrific Gullies in Hale (example)

  17. And in Hale’s Central Peak Area (example)

  18. But Hale’s Floor is Pretty Rough

  19. Candidate 4: Wirtz Crater (probably the best) White boxes show existing MGS MOC coverage to 15 May 2006.

  20. Example Gullies on NW Wirtz Wall

  21. Example Gullies on SE Wirtz Wall

  22. Example of Wirtz Crater Floor

  23. Summary

  24. Recommendation • Consider sending MSL to a gully site. • Unfortunately, there are very few gully sites accessible with a 20 km landing ellipse. • Recognizing that going to gullies may not be possible, for Planetary Protection reasons, means there is something wrong with the system— how can NASA have not designed a mission (and its feed-forwardness) that could go to the only known class of sites on Mars where liquid water may have been present in relatively recent times? Mmmmm, gullies!

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