4th MSL Landing Site Workshop Notes Monday Sept 27, 2010 Intro - John Grant focus on positives - theyre all good nobody voted off the island this time when do we start narrowing? 5th workshop - feed in go-to engineering info Mars program update - Mike Meyer repeat of yesterday re: landing sites - "we are going to challenge the quality of knowing" what do we know, what do we just think we know? MSL status report - Mike Watkins "MSL can look an NBA player in the eye and almost dunk" 90% increase in battery capacity new actuators need LOTS of heating can still do 28 samples and 4.5 km with margin at southern sites extra warmth in summer cancels out cold in the winter site safety - sites are indistinguishable in terms of several prespectives including safety traverse is the main difference MSL science objectives - John Grotzinger don't worry too much about traverses at this meeting whether or not the final site is your favorite, at some point have to think about what the best aspects of each is need to ID tactical science targets to predict traverses LSWG - Dawn Sumner nest steps: articulate science targets what ?s can be addressed (and where?) ?Minimum mission success criteria? No quantitative mission success requirements. There are capability requirements. set up website for community to suggest science targets? Preservations of organics or environments - Roger Summons much doubt about early life on earth comes from tectonism and weathering - different processes on mars context is critical strong oxidants and ionizing radiation are bad biological organics - patterns! Preservation in ancient cratered terrains - Jen Eigenbrode impacts:mars::tectonics:earth formation, concentration and preservation signatures of an ecosystem - where lithofacies variation and biosignatures overlap want geological framework in place before we land because surface time will be limited by contact instruments important to realize what we don't know complex histories will make things more difficult eberswalde is best for environment and framework (though she didn't say this outright) comment: but be prepared to throw framework completely out! Facies prediction on Mars - Dorothy Oehler we should look for shales/mudstones concentration of organics, sediment type, burial minerals important, but should start with regional basins, facies, etc Bethany Ehlmann: concern about type of life being considered. The biological potential of aqueous environments - Lindsey Tierney and Bruce Jakosky energy availability as a constraint look for chemical disequilibrium models of productivity: lots of assumptions holden and eberswalde - not a lot of evidence for redox mawrth - good evidence for oxidation of Fe gale - evidence for redox Discussion - led by Des Marais implications of obliquity? There are implications, we don't really know what they are yet... grotz: what is the risk that there is not chemoautotrophy in crater lakes? what is the concentration mechanism assuming life was there and was preserved? Pan Conrad: points out emphasis on organics rather than habitability grotz: public statement includes "preservation" so we need to make a best effort to find it sumner: chemolitho - mafics + water + CO2 gives reduction. expect it at the surface of mars. life on earth: genes include pieces of chemoauto genes, it's possible that photosynth just swamps extant chemoauto life Mineralogy CRISM maps - Frank Seelos new CRISM calibration removes a lot of high (spatial) frequency noise new Olindex2 - fewer false positives http://crism.jhuapl.edu/msl_landing_sites data quality metrics: left is detector temp, right is atmospheric dust CRISM mineral abundance mapping - Selby Cull estimating abundance and grain size volcano scan correction wont work fro this model teh atmosphere (radiative transfer) create look-up table for single scattering albedo for each scene use hapke mixing model (lots of assumptions) validation of ratioing ?how do you assess uncertainties? vary parameters individually to find (local) minimum in chi-squared space. Can rule out some local min as physically improbable test on lab spectra? working with bethany ehlmann ralph: we're looking at outcrop, not particulates. model can account for grain size and porostiy. ?: your ratio test tested the hapke mode, not the ratio. need to use lab data for "reality" not the model self-consistent models for geology and mineralogy from orbit and surface - Ray Arvidson ripples at oppy site formed in ancient easterly regime at higher obliquity "this is a little bit mind blowing, but..." (when showing a pca plot of soil chemistry) crism can do oversampling downtrack Site mineralogy - Milliken not all clays are created equal: mixed-layer clays mixed layers can tell you about diagenesis 2 distinct clay phases in ebeswalde - altered holden ejecta and deltas mawrth and gale have more smectites and mixed layer hydrated similar gale mineralogy in SE (including clays?) clays out on the plains west of mound (north end of dune field) looks like there are sulfates at mawrth (possibly below clays?) where are the "missing" salts after forming clays? at mawrth and gale they might be there (sulfates) maybe it's not a closed system (groundwater?) probably wont be able to tell between detrital/authigenic clays Discussion how do we explain immaturity at mawrth (impacts) and gale (burial) low permeability? little water post-deposition? back reaction? happens on earth but earth is very wet maybe we're overinterpreting the spectra Gale Gale context - Ken Edgett "imagine a road cut 3 miles high" Gale composition - Jim Bell Dawn Sumner DAY TWO Mawrth Vallis Overview - Joe Michalski mineralogically, lithologically diverse bedrock and sediments very ancient section cliam to have full sequence from clays to sulfates to oxides eras 2 types of phyllos in the ellipse ferrous hydrated phase detected? connected to regional/global picture examples of clays that were "clearly re-deposited" *why* do we see so much phyllo at Mawrth - good exposure rather than unique processes Mineralogy - janice Bishop tons of clays, some sulfate outcrops - diversity suggests redox gradients? no evidence for illitization or high-t mixed clays comment (McLennan): lack of illite may be due to lack of K on mars phyllos on mesa - phyllos may predate teh channel? phyllos in Oyama - filled with fluvially transported phyllos (how do they know they were transported?) shkuratov modelling - lots of phyllos ? how do you target biosignatures? - ?is stratigraphy a weathering profile? see eldar's talk Geology of the Landing Site - Eldar Noe Dobrea "in place deposits" does that just mean bedrock? don't all sites have that? access both noachian clays and hesperian caprock regional stratigraphy - can tie mawrth to 100s of km is compositional boundary depositional or diagenetic? inverted channels In the ellipse: capping unit - indurated aeolian? Al-phyllos - fractured, finely layered. mud/siltstone? Fe/Mg phyllos - high TI, bright, inverted fractures. altered sedimentary? dark unit - onlaps Fe/Mg unit, ridged. sand sheet? pitted/etched unit - dissolution? east part of ellipse and beyond No single process can describe the region Oyama's ejecta 1 km of rim is gone or buried - ejecta should be gone or buried too same stratigraphy inside oyama as outside! formation models? ejecta: +lots of craters/-makes bad layers, doesn't explain diversity airfall: +expected processes / - need too many events fluvio/lacustrine: +large system conceivable/ no basin! need thicker atm marine: +provides enclosed basin (north hemisphere!) / - where's the water? models: sedimentary, volcan/diagen, volc/diagen/pedogen all 3 models point to leaching Unknowns: origin of the phyllo-bearing layers (same as all sites on mars) origin of pyllos extend and pH of water dissecting uper unit nature of cap unit ?Grotz: seems liek Al-phyllo unit is "unglued" from physical stratigraphy. how do we know how old it is? physical layering doesn't "drape" but Al-phyllos do. One day, one month, one year at Mawrth - Damien Loizeau list of targets for MSL day one: what did we land on? month one: traverse example year one: explore the whole ellipse and beyond lobate ejecta just south of ellipse long-term targets: crater walls north of ellipse ?what do you see in oyama wall? - just dark cap unit, some exposures of underlying phyllos Conclusion - Jean-Pierre Bibring astrobio goals haven't changed since viking but capabilities have improved a LOT picture of mars *covered* in water claim that mawrth is older than most deltas we don't knwo the history of mawrth non-go-to better for sample return complexity as a plus "there is no equivalent on earth" access geology older than possible to access on earth - with context intact! mars could tell us about origin of life on earth Cratering at Mawrth - Dawn Sumner was uncomfortable with absence of a physical model for mawrth paper submitted: http://mygeologypage.ucdavis.edu/sumner/Sumner_mawrth.pdf used Crusta for virtual globe software (movies on youtube channel crustamars) did not find unambiguously sedimentary layring in the ellispe polygonal fracturing is related to modern surface conjugate fractures - regional stresses breccia "pods" - not planar, not layers in some places, these follow layers example of crater bench due to erosion, not layering can map dark "layers" 10 to 100s of meters layers rarely found on opposite sides of topo highs "scoop" shaped feature on crater wall with upturned beds - not a channel: an embedded impact crater accretionary tpography in sinuos looking layers just above "scoop" - maybe base surge but it is HUGE observtions inconsistent with "normal" (earth-like) sedimentary model how consistent is this with the mineralogy? Very! not consistent with through-going fluvial system which would require planing the topo impact origin might make it easier to get hydrous alteration could oyama have formed before rocks in ellipse? oyama interior is layered, ellipse much more brecciated Discussion Linda Kah: timing of oyama strata and ellipse rocks. Need to separate overprint of mineralogy from physical aspects. Dawn's model is based on physical aspects. Terrestrial person comment: Dawn's model fits nicely with Sudbury crater. This would be first time to see pre-LHB material. Could be very exciting! Bethany Ehlmann: obviously impact played a big role - it's a very old surface! Fluvial processes also played a role Michalski: light toned units exposed in walls of craters including oyama. so some of this stuff predates oyama. Then period of erosion, redeposition, even "mobilized" materials have same mineral strat Poulet: impacts would make composition heterogeneous. Sumner: disagrees. if you hit homogeneous rock, get homogeneous result. Arvidson: 1. might be oldest thickest preserved crust in SS, 2. layered! 3. probably representative 4. hydrated. The bad thing: too complex! Horton Newsom: struck by extensive stratigraphy (Eldar's work) terrestrial person: Impact was a really important process that we can't study as well on earth. Let's not shy away from impact complexity because that's representative of mars Eldar: confused by definition of Dawn's layers. assuming extensive (lacustrine) layers. other environments form mroe restricted layers lack of extensive layers could constrain env. in ellipse. Why don't we see more craters if they are so common in strat on crater wall Ken Tanaka: remember mawrth vallis itself - the oldest outflow channel. can learn a lot about outflow channels Michelle Minitti: VNIR says 50% clays, but TES doesn't see it. Why? Duke it out! Steve Ruff: some spectra look like weathered CRB. something that's clearly candidate phyllo, but question abundances. One explanation is crystallinity. Is VNIR seeing less-xtalline phyllos that TES can't see? Alian Wang: GRS data gives big picture. do we see high H at Mawrth? Eldar: No, there isn't a specific high at mawrth. Center of arabia is higher. Grotz: we haven't talked enough about possibility that mineral stratigraphy is younger and detached in time from physical strat. Nikolas Mangold: could be late alteration. 7 or 8 places on mars where we see this. Alteration must be before hesperian cap unit. Milliken: don't know if nontronite is detrital or not. Holden Holden Overview - Ross irwin located in big "Uzboi Ladon Morava Magaritifer" drainage system what is the Holden site all about? not just LTL rocks, not just fans *diversified habitability investigation* Pu-power may be unique to this mission - we should go south while we can what do you do when you land on the fans? don't just treatit as a safe landing strip and then leave get samples of noachian crust lost of other stuff to do with fans LTL materials types of evidence for paleolakes on Mars: context, stratigraphy, mineralogy only distinguishing feature between Holden and Eberswalde layers is that holden layeres are finer flat bedding, constrained in elevation great lists of what MSL would do at each major feature to evaporate all the water from the flood would take centuries outcrop of bedrock at end of traverse Summary 100m LTL strat section alluvial fans (on top of LTL) flodd deposits "bedrock" outcrops ?where else are there LTLs and are they all consistent with lakes? uzboi, ladon, holde, ritchie. fairly common. ?do we need meteoric precip? Yes for both holden and Eberswalde. Alluvial Fan Science Potential - Kelin Whipple fans are best evidence for early warm wet period eberswalde is a one-off but alluvial fans are all over ebeswalde drainage basin is much larger than holden's slope of holden fans suggests fluvial fans rather than debris flow (but debris flow fans are ok since they tend to form in huge rainstorms!) can estimate duration of formation and water volume using fan slope, volume and grain size measurements without in-situ can only guess fans may be younger than LTL or just prograding out across lacustrine environment ?Grotz: can we build a "hydrograph"? Probably can get peak discharge but not hydrograph (look this up) Holden Mineralogy - Jame Wray More diverse than we thought based on 5 of 32 CRISM observations look at crater wall upstream of the fan low and high Ca Pyrox, Mg and Fe Ol Fe/Mg phyllo and hydrated salt/zeolite megabreccia in extended mission could be valuable astrobio target possible breccia mounds in eastern ellispe Extensive Phyllo layer - Debra Buczowski exposed all along the rim of nirgal valles and Her Desher also shows up on nearby crater rims in-place phyllos in holden are different from those in the layer transported materials match better but could have been further altered after erosion or separated out during transport Hydrological context for holden and eberswalde: study of etythraea fossa - Peter Buhler southeast of holden older than holden but fluvial activity is younger than holden basins in fossa breached by valleys - lakes? Holden and Eberswalde are not just markers of flood events -contextualized hydrology Discussion Sumner: are LTLs distal equivalents of fluvial fans vs reflecting a temporal change? mineral story is consisten from ellipse to truncated fan to SE Irwin: fans extend on top of LTLs. alluvial gravel protects LTL Bell: great arguments for fan science. What about at Gale? can we objectively compare the science at the two fans? Whipple: they're pretty analogous, though you can't tie fan to mound very well. Irwin: Holden has some of the best fans, gale channel doesn't cut as deep Tanaka: craters on the fan surface - age? early hesperian compositional variability in fans? Whipple: no idea till we get there, but good stuff on the rim. if it's fluvial every bed will be mixed. debri flows will sample specific points from rim with more variation between beds Preservation potential of fans? Whipple: debris flows are gentler on weathered materials Grotz: any mapoing of the source terrain? Grant: it's just starting Sumner: low rock abundance in the ellipse. Whipple: could all be sandy material in the fan Irwin: points out that smallest rocks you can see in hirise are nearly a meter! Eberswalde Learning to read the fluvial system - Bill Dietrich "I am not Jim Rice" *a source to sink site* - well-defined drainage area, well exposed deposits deposits can guide modeling of hydrology, climate, sedimentology, geomorphic evolution no evidence that the delta was more extensive than now there's much more information in channels than that they just swept away material no subsidence makes things challenging improved odds of actually talking about hydrologic events rather than just peak flow "your pulse should quicken every time you see this picture [of the meander bend]" river channels can tell about discharge cant see depth or velocity from orbit rover obs would greatly reduce discharge uncertainty duration and freq of flows are difficult to estimate (even on earth) look for evidence of layering and sorting (chronic flow sorts better) meandering channels come from strength in the bank need to slow outer bank erosion on earth, need vegetation (cool movie of lab-generated channel) sources of strength on mars: mud - implications for eathering - silt and clay easy to transport but hard when dry! cement - implications for climate, mineralogy, geochem, hydrol, site evol ice - implies free running water in a frozen world - examples in alaska could look for ice wedges on mars many other sinuous ridges in eberswalde and elsewhere on mars great examples of inverted channels in atacama variation in channel morph suggests water entering lake fan volume is comparable to source channel volume ?mud-stabilized banks - could that just be clay-sized particles? composition should matter Hypotheses and science targets in the ellipse - Melissa Rice a lot of ancient surface no longer there, but still see old units (e.g. inverted channels) new hirise image ESP_018056_1555 - nice sinuous ridge pretty close to the ellipse possible breach from w lake to e lake narrow vein-like features common strat: LTL rock on polygonal fractured rock on discontinuous light rock polygonally fractured layer could be delta bottomsets - easily accessible in the ellipse but doesn't show up in mineral maps traverses: direct to delta - hit megabreccias, isolated mesa of plygonally fractured, LTLs and veins, then delta southern route - breccia, fractured LT unit, sunous ridge, vein ridge, southern fan and meander, delta north route - megabreccia, lobate feature w/ LTLs, inverted channels, ... delta ?Parker: is LT polygonal unit older than breccia? no, it onlaps the megabreccia ?how fast can we go if we gun it? wait for discussion tomorrow ?Tanaka: crater count can tell you how much has been removed Sink to source - Sanjeev Gupta "i was "skycraned into this area, given a three month battery life and told to worry about my career" "field geologists on earth would kill to have what we have at eberswalde" horizontal transect - distal to proximal eberswalde has a testable depositional model we're not going blind. if we don't find it we know why we went wrong Hypothesis: fluvio-deltais prograding into lake predict coarsening upward msl could tell us: grain sizes, facies associations, geometries, look for hiatusses... try to break walther's law inverted channels "sit proud" ?sumner: what do we expect to learn from the ground that you can't tell from orbit? can't see sed structures. we cn say it's a delta but can't know without details can look for time breaks, see if it all formed at once or not. look for simplest patterns in rock record ?des marais: how do we tell whether it was extremely intermittent? look for patterns. lack of patterns suggests intermittency ?significance of low slopes? grain size - shallower suggests smaller grains Evol and strat of Eberswalde basin - Kevin Lewis key questions: how much water, how long, lake? where does water come from? greater eberswalde basin ~5000 km2 2 km elevation range "let the traverse come to you" sample clasts from the basin local depressions above eberswalde planar units along south rim - at different elevations, suggest several stages channels rarely found below -1400m possibly controlled by overflow into eastern basin (like a dam) inverted channels occur at pour point MSL could resolve details of delta building phases "in eberswalde you have a built-in roadmap" you knwo where to drive to find certain fascies Where do you go to find the lake beds? as lobes move basinwards, build out over lakebeds, so lowest unit of delta should be distal facies ?is it possible that delta represents sediment only from below the small depressions? possibly, but other parts of the basin don't drain through there ?arvidson: how do we actually get time? can't calculate hiatuses, but fluvial can allow you to get models which predict times ?any terrace or other sign of paleostrandline in the crater? not much evidence The role of Holden in Eberswalde Fluvial - Nicolas Mangold fluvial deposits postdate holden ejecta blanket valleys carving ejecta of many craters between 25-40 degrees latitude hot ejecta melting ice? Holden could be an example of this precipitation not required? holden secondaries well preserved - may be really late impact lake could have been very transient ?whipple: no way that fan is a debris flow ?Ross Irwin: agree holden is relatively young but disagree with everything else. if you have ice plus ejecta and melt it, you get seepage but not enough discharge indicated by eberswalde. can't incise enough or transport enough sediment or maintain a lake. can't build valley networks by dewatering. Mangold: in noachian terrains we don't see secondaries. e.g. mojave crater (2-3 MYrs crater retention age) - snow falling on hot ejecta? Discussion Grant: Young Hale crater (young) shows channels, lots of older craters that don't show ?: structural presrvation potential is discussed, what's the chemical preservation potential? ?golombeck: where do we find bottomsets? Lewis: you land on them. don't know where exactly. Gupta: go to base of the cliff faces Milliken: strongest clay signatures are at front of delta low in strat, right where you expect. Low signal could be due to texture of rock. you would never see a black shale in crism, but that would be the holy grain for MSL. ?chemistry? Millike: holden ejecta has different clays, more Fe ?arguments for redox change? ?Jack Mustard: are the questions that we are addressing "what are the processes that form deltas on mars?" (Dietrich and Gupta get up) Whipple: if you don't care that's fine, but delta processes teach you about climate. Gupta: delta provides evidence to go test big hypotheses about climate Golombeck: it addresses two of MSL's main goals ?Mustard: if no organics, how does that affect significance of the habitability of mars? Gupta: i think we'll learn a lot about the climate history which addresses habitability. it's not like there's nothing to do if we don't find carbon Ehlmann: how do measurements of MSL supplement our knowledge beyond "wow there's a delta!" What do we look for ? (did they even hear bill dietrich's presentation?) Dietrich: we can transfer from a qualitative to a quantitative understanding. we go from "there was water on mars" to knowing lots more detail about environment. was it frozen, chemical precipitation? you can also say "oh wow, there are clay on mars" Ehlmann: skeptical that it tells us about the changing environment. Lewis: we don't have depositional rates at any of the sites, we have thickness. we can get quantitative estimates of time at eberswalde. need to fill basin 25x over to build this delta, meaning you need to get rid of water. harder to do with ice-covered lake Arvidson: big picture: 1) beautifully preserved structure, unique in solar system. 2) might be able to reconstruct hydrology 3) cool minerals 4) bottomsets are good for habitability evidence. it's not just Oh wow! Dietrich get's his own delta to look at. Eldar: focused on structure, what do we use all these compositional instruments for? (shock across the room) Scott McLennan: Context is everything for geochem too. ?: extended missoin targets? Holden! (hahaha) Oehler?: bottomsets are clearly best place on mars to look for organic carbon Summons: we know you improve your chances when you go to fine-grained seds deposited in water. confidence in context is the second big point that imporves your chances ?: it's exciting to compare deltas on mars and earth, but als need to be brave enough to explore what is different and confusing. wnat to see a mix of familiar and strange and wonderful in sites Ruff: lakebeds stripped away? are they in the ellipse or not? Lewis: Melissa is right Melissa Rice: see mesas of polygonally fractured unit (which is below delta beds) in ellipse Milliken: they have clay signatures, but weaker, with pyroxene ?: are there craters in the ellipse? Lewis: yes, there's an awesome one with awesome layers Grotz: I'm not 100% convinced it's a delta. The thing that keeps me up at night - we better be sure there was standing water there. Dietrich: I asked the same question when I was asked to give this talk. 1. stratigraphy 2. channels stop at common elevation that matches with overflow 3. change from meandering to digitate channels is a feature of a stream entering water. Alternative is an alluvial fan that's truncated. I've never seen an alluvial fan that looks like this. I don't know how it couldn't be a feature going into a shallow body of water. You don't go there to study delta formation. Why don't you see strandline? (heated discussion ensues) We should see them! No we shouldn't! Kieffer: what's the probability that this whole deposit was triggered by the holden impact? Huge implication on what we learn about habitability of mars. Irwin: I don't see how you can do it with the heat from holden's eject. completely inadequate. Looking for biosigs is high-risk high-return. Don't want to pass it up, but habitability investigation should be as broad as possible. Golombeck: Do we know the megabreccias are from holden? Edgett: not only are they from holden, but the pre-holden rock was junk in the bottom of the pre-holden basin Mangold: you can follow the breccia out of eberswalde into holden Golombeck: breccia was widespread, right Melissa? Breccia makes eberswalde not a one trick pony Melissa: Right, and there are different morphologies. some may be holden some may be bedrock Tanaka: there's no basin at the head of mwrth. considering age of holden and ebersw, may be seeing more features due to impact-released water Des Marais: this site is a singularity and is so well preserved that it suggests it was at the end of fluvial activity Grant: Lots of craters show this "shutoff" near the end Whipple: need to creat a tiger team to figure out if impact can be the source Grotz: You're hired. Irwin: in some cases you have 2 craters next to each other with fans coming from the ridge between. No aquifer! need precipitation Jim Bell: arvidson reminds us to "remember gusev". the apocryphal story is that we didn't expect to land on basalt. There was lots of debate before landing. Hearing a lot more consensus from world experts that Eberwswalde was a lake. Edgett says: "If these placese were not lakes, there were never lakes" Even a negative result would be huge Treiman: could this feature form with an ice cover? Dietrich: that's a central question. if it's frozen you don't get good shorelines. Whipple: hold the phone. if it's possible to build on a frozen lake, what's the difference from a crater floor? Chorus of responses: stream goes under the ice! Day 3 Characterization Plans for Engineering Analysis - Mike Watkins balance techincal risk and science value every mission before MSL "risk" has meant landing risk score=a*EDL risk + b*science value a>>b (but not infinitely so) you've got "what can your system do" and "what is mars doing to you?" for MSL this is the first predicted-to-be long-lived score=a*EDL risk + b*traverse risk + c*science value expand traverse risk into rissk of each waypoint risk of making it to waypoints is based on lots of things: how hard is teh traverse, what are you actually going to do? no black-and-white answer: some sites will be dark grey adn some will be light grey two key metrics: # of sam/chemin samples, total traverse distance conservative estimate: 10 samples for a 15 km drive or 28 samples for <5km drive probably optimistic for early mission, pessimistic for later mission defined different sol types for different seasons EDL risk is nearly the same for all sites (really incredible achievement) "MSL is moving toward a new world of landing site selection constraints that are more science driven and more surface ops driven" Atmosphere and Climate context - Ashwin Vasavada (deputy project scientist) the "MSL Council of Atmospheres" arrive at mars right now + one mars year Next time mars comes around the sun, we'll be thre to meet it Land in late N summer, late S winter lots of vigourous convection in north very cold in the south, storms in south are south of sites Gale is pretty free of concern weather-wise spacecraft steers itself through atmosphere (that's why we have a nice circular ellipse) we're flying through 100km of weather - most sensitive to atm at 2-30 km altitude lots of modeling to predict weather - use a variety of models, test against observations use scientific models GCM feeds into mesoscale models "we're using the best models available in the world" dust storm frequency from MOC-WA and MARCI have tried to simulate local/regional dust storms (don't expect global storms) simulate "dust bomb" - smallish dust storms propellant margin - "this is like the lunar lander game we all used to play" can optimize for a particular site once we choose it "atmospheric safety is not likely to be a driver for site selection" (at this point, previous sites wre more dangerous) Climatology of landing sites for mission design/performance strongly coupled to temperatures (need to heat the actuators) "stress test case" is a far south site that gets near frost point of CO2 and up to nearly 40C holden and eberswalde - nice and warm in the summer, very cold in winter mawrth is pretty mild all year long ?edgett: if we had actually launched on time and were going to holden, we would actually see dust lifting. is that ok?! we can survive a local or regional storm occurring at our site ?Ruff: has anyone assessed where in the ellipse previous missions have landed? is it random? Watkins: previous missions we didn't have the entry guidance system. MSL uses active guidance. probably can't compare Meter-scale topography - Ken Herkenhoff (for Randy kirk) HiRISE DTMs vertical precision depends on pixel scale, base-to-height ratio, ability to match features horizontal resolution no better than 3-5 pix DTM can have a block appearance combine older algorithm that doesn't make the blocks and newer high-res method get soem artifacts get slope errors of order 1 degree clouds can really screw up DEM spacecraft jitter can cause problems too re-image jittery areas or use jitter adjusting algorithm 15 DTMs in final four sites + 2 traverse DTMs for gale and Holden some do-overs, extras eberswalde ellipse is roughest, gale and holden are smoothest ellipses traverse areas are much rougher (that's why they're go-to!) acceptable traverse paths do exist within teh rough areas http://hirise.lpl.arizona.edu/dtm Rock in the ellipses - Matt Golombeck engineers define a rock as something you don't want to land on or to get in your way HiRISE changed everything - e.g. phoenix site selection automated rock counting segment out the shadows, fit an ellipse mapped 10 million rocks on northern plains for phoenix improved the algorithm for MSL can see rocks with 3-pixel shadows edit out non-rock shadows such as scarps "I think there's one rock in holden" gale rock density similar to gusev eberswalde has a big knob of rocks, but mostly good (.054% rocky) ?Vaniman: worried about taking out scarps entirely because those are dangerous! Golombeck: we still measure those as a risk, just don't use them for matching the model ?Sullivan: we touch down on our wheels. are little rocks dangerous? It looks like the major concern is stress propagation from wheel to suspension. But doesn't look as bad as thought previously. Biggest risk is a rock in the belly. ?Lakdawalla: (inaudible) probably suggested citizen science to help out? Golombeck: we could try it, but we're pretty comfortable with the model fits ?Ruff: Concern about a hobbled rover on landing. how much of a concern should we have? engineer: Don't worry about it. We've don a lot of detailed stress analysis. Recently found a couple areas of "negative margin" went in and tested or re-analyzed. basically means you're going beyond linear respinses, but doen't mean failure. We're not worried about breaking the rover. ?is there a need to do drop tests? There have been some, there will be more, plus static tests, plus more analysis Thermal Inertia - Robin Fergason bottom line: TI is not a factor for drivability. eberswalde has the most variation due to dark material vs exposed bedrock 2-4 cm of dust would completely mask underlying - don't see that low of TI in any ellipse gale has moderate and high (high is in the fan where soil is stripped away) holden is extremely uniform - bedforms are probably indurated or coarse-grained or seeing bedrock between them mawrth is pretty variable too, [my comment: seems to correspond to clay type?] ?Arvidson: How does TI compare to Spirit an Opp sites? both are around 200 (much lower than MSL sites which are 300-600) Arvidson: TI doesn't guarantee safety (examples from MER) ?Eldar: Mawrth TI variation is compositional ?Wray: how do we reconcile High TI with altered nature of rocks at edge of delta? If it's cemeted well enough it could be high TI, plus might fill the themis FOV better. [Fergason keeps saying High TI = unaltered. I'm very skeptical] Overview of surface characteristics of sites - Golombeck "New" ellipses! Due e-w ellipses 25x20 km eberswalde is without question the roughest site [slides are flying by fast! lots of pictures] look at 6 previous landing sites as ground truth dont want to land on the "foo foo dust" opportunity = a parking lot Spirit - pebbly phoenix smooth and dusty Pathfinder - very rocky Viking 2 - rocky, but smoother at longer lengths 900m relief - no worries 5m slopes dramatically rougher at Mawrth and Eberswalde but not much of a problem columbia hills-like releif "inescapable hazards" - might you land in a crater and be trapped? they look escapable in eberswalde: mesa! could probably drive off of it [start off with a great view] Inescapable dunes none of the sites, even the dunes at gale are inescapable [83 slides total in 30 minutes!] ?Edgett: So if you landed on a dune in Gale, you're ok? Yes, this lander tolerates slopes up to 30 degrees. Drive down to interdunes where there are routes through ?Ruff: surprised at lack of concern with bedforms in Holden. ar we stuck in troughs? Could probably corss them, but easier to parallel them ?Sullivan: any concern about spoofing the radar with stuff blowing around from rockets? We are concerned, we're looking at it. Testing it over similar dusty surfaces on earth. We're not panicked. Could probably fly through the blowing stuff. We might not like it but could do it. ?Sullivan: If we land on that plateau, it would be a nice "lion king" scenario, but are we worried about going down steep, bumpy slopes? See next talk EDL safety - Devin Kipp large portion of entry flying at pretty constant altitude, controll downrange target decellerate to mach 2 and open parachute once subsonic, drop the heat shield and turn on radar radar starts making measurements while still on chute stop taking altitude measurements once the rover is lowered, still measure velocity near surface, jets interact with surface, blowing stuff around once rover touches down "hopefully the rover-surface interaction perpetuates for the rest of the mission" can tune flight software to even out the risk across the sites 5-beam radar not actually looking at the exact spot we're landing as you come it kill all horizontal velocity, fly at very low altitude at near-constant velocity for up to 260 meters largest chance or radar-related failure is eberswalde at .001% (.0001% for other sites) lots of things could go wrong related to terrain sliding down a steep slope, not enough fuel, tangle with bridles, blast the rover with the plume or sandblast it loads and stability are really all that matters major focus since last meeting we're fine, 99% of the time overall landing success rate 98-99% we all know it's not true that we have equal prob of landing anywhere in the ellispe next step is convolve this Touchdown won't discriminate between sites but might influence final ellipse placement ?Minitti: what's the ability to aim for a certain spot in the ellipse, is that totally impossible? two ways to do that: with more analysis might be able to shrink ellipse, or you could accept a little more risk and reposition the ellips ?Bell: hoe much swinging and gyration is going on so we can use MARDI images? 3 degrees of max deviation from straight down at 300 feet altitude. max twist 35 degrees Traversibility - Paolo Belutta "I'm italian, please no jokes about italian drivers on mars!" use driving criteria similar to MER pretty similar except that MSL can drive over bigger obstacles (50 cm max) 15 degree slop on sand, 30 degrees on bedrock would take four years of work to analyze full travers for all the sites use an automated process MSL top speed is just slightly faster than MER not the biggest factor slopes are the biggest factor for trafficability also, obstacles (mostly rocks) compute a travesibility cost map combination of high slopes and obstacles - very time-expensive to drive co-registration of the data is *really important* subdivide terrain into 25 meter tiles and compute the cost to traverse can't traverse things that are casting a shadow end result - want to be able to go from "cost" to drives and # sols ?Arvidson: need to mine Spirit and Opportunity data to get more quantitative mapping and be able to avoid dangerous soils? ?Ehlmann: more info about driving modes for MSL? Rates of driving for visodo, blind, etc? Blind driving is 150m/hr for MSL. (MER is 135 per hour) dont have details of flight software for other modes. Autonav for MER is 30m/hr. For MER with outonav and visodo it is 15m/hr ?: confidence in steep slope driving? We've done it with 5 wheels on spirit ?Jim Bell: We've got higher res cameras, and Pu power. Why nto assume MSL will kick MER's butt on driving distance per day? There will be other limitations on drive distance and don't have that data yet. ?Aharonson: soils may be worst danger more than obstacles/scarps? DISCUSSION Let's keep it positive! Steering committee listed some key points for each site Everyone agrees that all 4 sites are worth considering no (known) fatal flaws for the sites Ruff: that question didn't include go-to Golombek: still looking at that, so can't really consider go-to yet Impromptu stratigraphy of Holden/Eberswalde area - Ken Tanaka debate of whether the channels feeding into eberswalde could have been produces by Holden impact there's some merit to considering this possibility holden impacted potentially water-rich sediments extra thick eject to NW of holden - oblique impact? valleys feeding eberswalve - low drainage density rather than dense networks suggestive of precip ladon vallis - collapsed floor within holden - fractures and warping of the floor in the S Thsi latitude is where the hesperian outflow channels formed - so likely groundwater geothermally driven groundwater flow you do need recharge as ross irwin pointed out lake could give local precipitation geothermal springs active for 100,000 to 1,000,000 years Grant: nearby craters have fans so there must have been a broader system Irwin: don't have temporal resolution to say eberswalde formed right after impact. releasing groundwater with ejecta heat couldn't erode enough GALE ?Oehler: reasoning behind lacustrine deposits? Sumner: laterally continuous beds over tens of km implies regionally uniform depositional environment. interpret as lake or playa-like. Airfall could also produce uniform thickness. Don't think there were duneforms, some marker beds look consistent with ash. they're flat with no bedforms. no intermixing of layer types which would happen w/ aeolian Also, to channel Edgett: if you didn't have a lake there, you probably didnt have lakes on mars ?Ehlmann: do we know groundwater created a lake? Edgett: I never said lake. But you need wetness to lithify this mound "groundwater" bullet edited milliken: airfall is not the same as aeolian. leave aeolian as a possibility we know channels have cut through the mound, so some fraction has to be fluvial Newsom: many publications show a many-km-deep hole fills with groundwater Grant: but there's no clear evidence. future effort is to help make that part of consensus definition of diversity? Arvidson: make hypotheses explicit Sumner: hypothesis: how did the environment and mineralogical signatures reflect the aqueous processes int he crater Arvidson: Is gale a place where we can test the hypothesis that this big-ass mound formed in a lake? age of the strata? where would MSL go to look for preserved organics? Edgett: there are no deposits on the wall of the crater , that's done. if you've looked just at one site, look at a different one MAWRTH Over-arching hypothesis: Mawrth records geologic processes during early martian history when aqueous phyllo-forming processes were pervasive and persistent and provides the opportunity to understand early habitability. need to figure out timing of strat and mineralogy. depositional settings need to be refined. Importance of impacts? Is there a go-to target for Mawrth? lots of things listed, but what's the top priority? maybe descend the layers of Mawrth vallis Bibring: Need more astrobiology study for Mawrth. Need the concrete targets HOLDEN Hypothesis: Holden preserves evidence of a fluvial-lacustrine system that provides the opp to apply a ssystems approach to evaluating a sustained, habitable environment. Future work: origin of LTLDs? list of targets. look at stratal geometries EBERSWALDE Hypothesis: Eberswalde crater stratigraphy, geomorphology and mineralogy records the evolution of a crater lake and associated fluvio-deltaic systems and additionally represents a habitable sedimentary environment that is fvorable to the presrvation of organics. DISCUSSION (for real this time) Mike Meyer: in laying out the target waypoints, the first point is obviously where you land. What can be done in the first couple months of the mission? Grotz: We're not just gonna dirve and not do science. ID and prioritize targets in the ellispe Ruff: Can we see the probability distribution of landing? Sure, but it's pretty circular gaussian Grant: if the ellipses shrink, you might move it away from hazards or closer to go-to, or near key targets in the ellipse Millike: if you don't have organics being produced in the lake, how well are detrital organics preserved? ?: in antarctic, detrital organics get in the way of those formed in-situ! Des Marais: it's amazing how much is destroyed in transport on continental shelf Eigenbrode: will depend on organics composition Milliken: For mawrth, the mineral contact cuts across bedding suggesting it's diagenetic. jarosite suggests acidic. What does that imply for preservation? Eldar: expose both altered and stuff that is from deeper. Michalski: in terms of preservation, pedogenesis is scary! but we might be wrong, and we have access to the deeper clays [a bunch of comments from Mawrth fans about how great minerals are] Eigenbrode: if you go through changes in conditions, you lose info about environment. when it comes to a more recent habitable env, there's a whole slew of things to look for Sumner: 2 issues at mawrth 1. lots of these maybe habitable envs, the concentration even on earth is very low. preservation tends to be very sparse and patchy. Need an environment and preservation conditions that are predictable silica in fractures would be great, but we need to know where that is. What are the *targets* for mawrth? Where do we look for organics in Mawrth Irwin: if you're standing at N-H transition, going forward and back in time it's drier. more water available. It's not gonna be brazil, but it might be utah. Wang: with laser you can tell hydration state (really?) you can save yourr silver bullet for the really good stuff Abby ?: use geol context to test different hypoteheses for origin of organics if you find them. Mahaffey: erosion rates would be really valuable for avoiding cosmic ray degratation Grotz: need to know more about preservation of organics in fractures. also think more about impactites let's pretend mawrth is dry: what could we learn from a time series of breccia deposits Newsom: want hydrothermal veins as back-up. look hard in crism data at high and low-res. Grotz: what about petrology of a stack of impactites? Newsom: one of the holy grails is to find mantle rocks. Minitti: best example for understanding what you get from impacts - Apollo samples! Also: please stop calling it a basalt prison! That first analysis spirit made totally changed out viewpoint of how mars differentiated ruled out magma ocean based on Ca/Al ratio. Throw us a bone every once in a while! Grant: maybe we should use current orbital assests while we have them to start looking at future sites 28 possible new sites are imaged, 11 stereo -5-+25 latitude looks likely for the 2018 mission there is funding for this could immature clays at gale and mawrth be due to late alteration? [arcane discussion of clay alteration ensues] Wray: how confident are we that it is mixed-layer clays? [back and forth between bethany and ralph for ten minutes, while astrobiologists on the other side of the room aren't given a chance to speak] Sumner: to address the impication for organic preservation. clays can only protect organics rpesent wehn they form or after. in theory you can make up scenarios where diagenetic clays can preserve organics Eigenbrode: bottom line - a record of habitability is a context. if you start to change that in any way, you lose info from the first. diagenesis can overprint the original