If these ideas strike you as interesting, and if you are looking for a career in Planetary Science that is guaranteed to start off mired in controversy, but at the leading edge of science, then try these:-
Potential Ph.D. Studies in Planetary Science -Mars studies within a "White Mars" Paradigm
1) Kasei Valles morphology used to analyse flow process and scale of the Outburst "Floods".
Background
Kasei Valles is perhaps one of the best defined valley systems on Mars. Stretching for over 1,000 km from its source in Coprates Chasma to its eventual merging into the northern plains, the valley system exhibits a spectacular variety of morphologies. These include wide shallow plains, narrow incised valleys, and simple or complex multiple channels. The Kasei system is an ideal testbed for flow models of the outburst "floods" and may hold the key to distinguishing between the traditional catastrophic water-flood models and the new CO2 vapour-supported density flow models.
Plan of Research
MOLA profiles will be assembled and, if necessary, relevelled to produce a detailed framework of topographic profiles. A local remosaicing of the Viking MDIM will be produced to coregister the two datasets as accurately as possible. Clear offsets exist between the Viking product and the MOLA dataset, due to changes in the adopted mapping datum. Smaller offsets exist within the Viking dataset itself, and these will also be compensated by geometric reprojection of the original images. Appropriate MGS images will also be embedded into a multi-layered dataset allowing high-resolution views to be accessed where available.
Infill to the MOLA topographic framework will be provided by photogrammetry and shape-from-shading analysis of Viking era intermediate resolution images to produce a detailed Digital Terrain Model (DTM) of Kasei Valles. In itself this will be a significant product for the planetary community and it is anticipated that the work will be carried out in cooperation with USGS and NASA scientists to ensure consistency, quality control, and acceptance of the final product.
Image analysis of the new mosaic will be one focus of the project. Detailed mapping of terrains and their possible interpretaion will be compiled to update existing geologic maps within a new paradigm of transport processes and event timescales.
Simultaneously, numerical modelling of flow processes within the channels defined by the new high-resolution DTM will allow insights into flow depths and velocities, under different assumptions as to flow process. Quantitative assessment of the volumes of water- vs gas-supported flows and of the sediment transported from erosional to depositional areas will be used to place bounds on the scale and processes involved in the outburst "floods".
During the course of the research, the candidate will be expected to modify and develop the detailed plan in the light of ongoing results, aiming for a scientifically significant outcome and timely completion. In particular, comparisons with other channel systems on Mars and Earth will be included in such detail as is required.
Key datasets:
· Extensive Viking era images including
a continuous MDIM mosaic and numerous higher resolution images
· MGS - MOC targetted images at extremely
high resolution
· MGS - MOC wide angle images showing
seasonal, climatic, and illumination variations over an extensive period
· MGS - MOLA topographic profiles and
derived grids
· MGS - TES thermal measurements and
derived rock abundance maps
· Spectroscopic data and inferred lithology
distributions
Skills required (or to be developed):
· Image analysis
· Manipulation of large digital datasets
of image and property data
· 3-D surface modelling
· Simple Programming
· Numerical analysis of fluidised flows
2) Structural state of the northern plains and its implications for Mars thermal and volatile history.
Background
The new topographic data supplied by the Mars Orbiting Laser Altimeter (MOLA) has revealed a previously unknown but pervasive set of wrinkle ridges throughout the lowland plains of Mars. These areas were previously believed to be smooth and featureless except for the relatively sparse young craters. Now, a new understanding is required. Possibilities include a network of lava tubes, suggesting a volcanic origin for the plains or that the features are compressional thrusts, as observed on Mercury. This latter alternative would have significant implications for the thermal state of Mars' interior. Analysing the distribution of wrinkle ridges in terms of local, regional, and global tectonics is a major step in understanding the evolution of the Red Planet.
Plan of Research
A compilation and relevelling of MOLA data will be used to build a detailed Digital Terrain Model for all of Mars' surface. This will be used, in conjunction with prior Viking-era and MGS-based work to analyse the stress distribution of Mars' surface. An integrated analysis of the topographic load, gravity anomaly, and near-surface stress state will allow testing of the hypothesis that the wrinkles are tectonic in origin.
In the event that the wrinkles are tectonic, then detailed studies of the wrinkle morphology in terms of asymmetry and relief will permit analysis of the underlying fault and fold elements responsible for this surface expression. Measurements of integrated expansion and contraction of Mars' surface as a function of geological age will permit strong constraints to be placed on the planet's thermal history and estimates made of its present-day internal temperature and heat flow. Prior work by the MOLA team on the relationship between long-wavelength gravity and topography, with implications for the evolution of crustal thickness on Mars will be used as a separate testable set of data to compare with the results of this study.
If the wrinkles fail to stand up as viable tectonic features, then mapping of their geometry and distribution will be used to analyse their mode of origin. The wrinkle ridges will be analysed in detail and compared to analogs on other planets. Alternative models include lava tubes, large-scale sediment waves, compaction features related to buried craters or possibly variable distribution of subsurface ices or volatiles. In any event, these alternatives must be tested in order for the tectonic hypothesis to gain rigour.
During the course of the research, the candidate will be expected to modify and develop the detailed plan in the light of ongoing results, aiming for a scientifically significant outcome and timely completion. One key decision point will be whether the wrinkle ridges adequately match a tectonic origin after the first phase of analysis. A negative answer to this test will require the study to focus on alternative formation mechanisms.
Key datasets:
· MGS - MOLA topographic profiles and
derived grids
· Extensive Viking era images including
a continuous MDIM mosaic and numerous higher resolution images
· MGS - MOC targetted images at extremely
high resolution
· Regional-scale Gravity data from
Viking and MGS orbit determination
Skills required (or to be developed):
· Image analysis
· Manipulation of large digital datasets
of image and property data
· 3-D surface modelling
· Simple Programming
· Thermal models of both deep and near-surface
structures
3) Atmospheric modelling of a Condensable CO2 atmosphere on early Mars in the presence of impact cratering.
Background
The Noachian of Mars is a poorly understood epoch when ongoing major bombardment was actively modifying the planetary surface. Dating from this time there is evidence of active erosion of landforms, of deposition of thick layered terrains, and of the formation of the Dendritic Valley Networks. These are probably all linked to the state of the early atmosphere. Conventional models of a warm and wet early Mars suggest that this was a time of persistence of a ~0.5 to 2 bar CO2 atmosphere, and that liquid water is responsible for most of the features we see. Indeed, a Northern Ocean of Noachian age has been invoked by some authors.
An alternative model is that the planet was an iceworld at this time, poorly warmed by the Faint Young Sun, and that any thick atmosphere was transient and ephemeral, associated with the heat pulse of major impacts. Detailed numerical studies of the stability of atmospheres on a cold early Mars and the processes of atmospheric generation and collapse associated with major impacts will allow a properly objective analysis of the merits of competing hypotheses for early Mars.
Plan of Research
Numerical models for Mars' early atmosphere will be constructed, involving a variety of 1-D, 2-D, and 3-D formulations for the vertical structure, latitudinal zonation, and dynamics of a CO2-dominated composition. These will draw upon prior work by Kasting, Pollack, Zubrin, Pierrehumbert etc. Models will be calibrated against the proven dynamics of modern Mars and then applied to Mars' past by varying parameters such as solar insolation, volatile availability, surface albedo and other potential secular changes. In the process, considerable information will be derived regarding habitable limits for terrestrial planets.
Once a stable set of steady-state models is available, the more complex and time-variant issue of impact heating will be addressed. In the simplest cases, these models may be viewed as a variant case to a non-rotating planet, where one hemisphere is exposed to a higher heat source than the other. This well-understood case results in volatile loss from the warm hemisphere and condensation on the cold hemisphere. Depending on the thermal state of the surface and the atmospheric density, the precipitation may be liquid or solid, and of water or CO2. Analysis of this special case will already yield interesting intermediate results.
A final set of models for more complex and perhaps stochastic situations involving time-varying 3-D heating will be the goal of this project. The outcomes from this stage of the work will have significant bearing on interpretations of the Noachian Dendritic Valley Networks. The results will place strong Constraints on their formation mechanisms and duration, the fluids involved, and whether this was a local or a global process.
During the course of the research, the candidate will be expected to modify and develop the detailed plan in the light of ongoing results, aiming for a scientifically significant outcome and timely completion.
Key datasets:
· Viking and Pathfinder atmospheric
and surface data
· Modern Mars GCMS climate modelling
· Prior work on Early Mars atmospheres
Skills required (or to be developed):
· A familiarity with atmospheric dynamics
is preferred
· Detailed atmospheric modelling
· Programming
· Numerical analysis of complex quasi-static
atmospheres and stability limits
· Numerical analysis of transient states
under gross non-equilibrium conditions
4) Physical studies of cryogenic and hyperbaric volatiles on Mars and their effects on rocks and regoliths.
Background
The prevailing paradigm for Mars surface evolution is that Mars was formerly warmer and wetter than it is today due to atmospheric greenhouse effects and perhaps secular loss of volatiles. A new competing hypothesis predicts that Mars has in fact always been cold and dry and that the features we see at its surface are signs of the activity of subsurface liquid CO2, not water. This new model makes a number of challenging predictions about mineralogy of surface and subsurface materials, and requires additional data on the formation, stability, and decomposition of CO2-bearing phases in the regolith.
In particular, data is needed on the behaviour of CO2-clathrate and its rate of decomposition as a function of external pressure and temperature, and the influence of physical and thermal agitation of clathrate/regolith mixtures.
Plan of Research
Equipment will be developed to study CO2 and CO2/water mixtures at a variety of low temperatures and moderate to high pressures appropriate to the subsurface of Mars. Stability fields and reaction rates will be quantified and the results used to improve our understanding of the likely state of volatiles in the subsurface of Mars, particularly of CO2-clathrates. This result will be used to compare with data returned from orbital radar sounding missions and, if available in the relevant timeframe, other geophysical studies planned for Mars.
Once formed, CO2-clathrates will be studied with particular attention to their physical properties and breakdown processes and rates. New data from images of the polar regions in springtime shows unusual behaviour related to the breakdown of dry ice and possibly also of clathrate. One key study will be the stability and degassing rate of clathrates involved in mass-flows. Transport of material inevitably involves collisions, grinding, and intense mixing processes. The effects of these on clathrate and dry ice decomposition rate will be simulated by heating, grinding, shearing etc.
In parallel, a series of experiments will be conducted with candidate Mars regolith materials including weathered and unweathered basalts and other appropriate analogs. Dense-phase anhydrous CO2 treatment of these samples will result in chemical alteration producing compounds rather different than in terrestrial aqueous-dominated systems. Appropriate analytical techniques will be used to characterise the changes to the bulk regolith, and any extracts derived from it by the CO2 leaching process.
During the course of the research, the candidate will be expected to modify and develop the detailed plan in the light of ongoing results, aiming for a scientifically significant outcome and timely completion.
Key datasets:
· Viking and Pathfinder Lander data
regarding composition and physical state of surface materials
· Spectroscopic data and inferred lithology
distributions
· Prior work on Supercritical CO2 treatment
of terrestrial materials
· Prior work on deepwater methane clathrates
Skills required (or to be developed):
· Laboratory Practical skills
· Experimental Safety
· Equipment design
· Protocol Design
· Investigative techniques such as
Electron Microscopy, XRF, XRD, GCMS etc.
· Data Analysis
5) Isidis Basin - a potential focus of cryovolcanic activity on Mars.
Background
Isidis Basin on Mars is filled by a smooth-surfaced unit of relatively young age, coaeval with the main northern plains depocentre but probably filled by a separate set of flows. The nature of these flows is at present indeterminate with fluvial, volcanic, marine, pyroclastic, and other exotic processes invoked. Key to understanding the deposits is the observation that many tens of thousands of small cones dot the plains in strings and chains. Each cone bears a small summit depression and they bear strong similarities to tuff cones on Earth. Nonetheless, there are dissimilarities too, for instance none of the 30,000 cones has any trace of a lava tongue or flow emerging from it, nor are any young flows seen on the plains surface.
One possible explanation is that these are pseudocraters formed by expansion of volatiles from a buried layer, and that the cones are formed by secondary processes without the direct involvement of magma. Within this context, two alternative models exist: The cones may have been formed by high temperature expansion of water, requiring near-magmatic temperatures and implying that the basin fill is essentially volcanic, perhaps a massive ignimbrite. The alternative is that the cones were formed at substantially lower, possibly cryogenic, temperatures and that the responsible volatile is CO2. This latter model implies a cold emplacement mechanism for the deposits. Alternatives do exist where the cones are formed in relation to much younger heating or fluid invasion events. These too must be carefully tested.
Plan of Research
MOLA profiles will be assembled and, if necessary, relevelled to produce a detailed framework of topographic profiles. A local remosaicing of the Viking MDIM will be produced to coregister the two datasets as accurately as possible. The study will rely heavily on high resolution Viking and MOC products to image the cones and conduct relative-age estimates from crater counts on representative terrains such as cone flanks and peaks vs background plains. TES rock abundance data will be integrated.
Image analysis of the new mosaic will be one focus of the project. Detailed mapping of terrains and their possible interpretation will be compiled to update existing geologic maps. Simultaneously, numerical modelling of cone-building processes will allow insights into fluid temperatures, abundance and expansion pressures, under different assumptions as to flow process. The results will be integrated into an understanding of the processes responsible for cone-building in Isidis Basin. If time permits, the analysis will be extended to other cone-like features elsewhere in the northern plains.
During the course of the research, the candidate will be expected to modify and develop the detailed plan in the light of ongoing results, aiming for a scientifically significant outcome and timely completion. In particular, comparisons with volcanic and cryovolcanic features on Earth, Mars, and other solar system bodies will be included in such detail as is required.
Key datasets:
· Extensive Viking era images including
a continuous MDIM mosaic and numerous higher resolution images
· MGS - MOC targetted images at extremely
high resolution
· MGS - MOLA topographic profiles and
derived grids
· MGS - TES thermal measurements and
derived rock abundance maps
· Spectroscopic data and inferred lithology
distributions
Skills required (or to be developed):
· Image analysis
· Manipulation of digital datasets
of image and property data
· 3-D surface modelling
· Simple Programming
· Understanding of volcanic analogues
· Numerical analysis of cone-building
processes
Maintained
by: Nick Hoffman
Email: nhoffman@unimelb.edu.au