LEADING MSL TO WATER: PALEOLACUSTRINE LANDING SITES REDUX. J.W. Rice, Jr., Mars Space Flight Facility, Department of Geosciences, Arizona StateUniversity, Tempe, AZ 85287, [email protected] Introduction: The highest priority landing site tered bedrock outcrops. This is consistent with a for achieving the scientific objectives (assessment lacustrine setting. of local region for habitat potential for past or present life) of the Mars Science Laboratory will Holden Crater be a paleolacustrine basin containing accessible Location: 26.1.S,326E layered sediments. Ideally, this type of landing Diameter: 154 km site would be selected from both morphologic and Elevation: –2.200km mineralogic evidence. The MER Project had the Thermal Inertia: 320-470 SI units luxury of selecting two landing sites. One site Geology: Uzboi Vallis cuts the SW rim of based on mineralogy (Meridiani Planum) and one Holden. The southern floor of Holden contains on morphology (Gusev Crater). To date the Me- laterally continuous layered sediments, distribu- ridiani site has proven to be the wettest. The mor- tary fan (225km2), inverted channels and mean- phologic approach was unsuccessfully attempted dering channels. Medium thermal inertia repre- with the Gusev Crater site. However, it should be sents a combination of coarser loose particles, mentioned that some of us (voices in the wilder- crusted fines, a fair number of scattered rocks, ness) argued that the morphologic and geologic and/or perhaps a few scattered bedrock outcrops. evidence in Gusev Crater was much more com- This is consistent with a lacustrine setting. plicated and that the commonly accepted lacus- trine story was flawed. MSL will only get one Palos Crater chance. The morphologic approach can success- Location: 2.7S,110.8E fully select the site if it contains overwhelming Diameter: 55 km evidence of a true lacustrine setting. Some condi- Elevation: –0.750km tions that must be met include evidence of per- Thermal Inertia: 320-520 SI units sistent flow (meandering channels, meander cut- Geology: Tinto Vallis dissects the SW rim of Pa- offs and scrolls, inverted channels, cross cutting los. Crater floor is made of laterally continuous channels), ponding in a basin, and deposition of layered sediments. Medium thermal inertia repre- laterally continuous layered materials. Obviously, sents a combination of coarser loose particles, supporting mineralogic evidence would aid in crusted fines, a fair number of scattered rocks, providing the ‘slam dunk’ for site selection. Un- and/or perhaps a few scattered bedrock outcrops. fortunately, the surface of Mars does not always This is consistent with a lacustrine setting. cooperate due to its annoying dusty veil of sup- pression. All of the following sites satisfy engi- Nili Fossae Crater neering requirements. Location: 18.4.N,77.68E Candidate Sites: Diameter: 45 km Eberswalde Crater Elevation: –2.600km Location: 23.8.S,326.7E Thermal Inertia: 290-320 SI units Diameter: 65 km Geology: Valley networks cut northern rim of Elevation: –1.480km crater. Crater floor contains fans (56km2), layered Thermal Inertia: 380-510 SI units sediments and cross cutting inverted channels. Geology: Numerous channels cut western rim of Medium thermal inertia represents a combination Eberswalde. Distributary multi lobate fan of coarser loose particles, crusted fines, a fair (115km2) composed of layered sediment, mean- number of scattered rocks, and/or perhaps a few dering channels, inverted channels, meander cut- scattered bedrock outcrops. This is consistent offs and scrolls, cross cutting channels. Medium with a lacustrine setting. thermal inertia represents a combination of coarser loose particles, crusted fines, a fair num- ber of scattered rocks, and/or perhaps a few scat-.