• NEANIAS Space Research Community

Several paradigm shifts have occurred over the past several decades as our understanding of the hydrologic and climatic history of Mars has evolved. It is generally accepted that the early climate on Mars was capable of sustaining an active hydrological cycle, and that (possibly episodic) precipitation and runoff formed the low-to-mid latitude belt of valley networks. Age analyses from crater counts suggests a sudden decline in fluvial activity around the Noachian-Hesperian boundary, presumably associated with the loss of the early denser atmosphere. The climate in the Hesperian and Amazonian was generally considered less favorable for precipitation (most likely snow) and runoff. This paradigm, however, is being challenged by a growing suite of post-Noachian fluvial landforms that support evidence for a late, widespread episode(s) of aqueous activity. Because modification by water and ice on a paleolandscape is one of the most unambiguous markers of past climate, this dissertation investigates fresh shallow valleys (FSVs), deltas, paleolakes, alluvial fans and aqueous-rich ejecta deposits in northern Arabia Terra and northwestern Noachis Terra that formed in the Hesperian and Amazonian. The objective of this dissertation is to provide insight into the environment and associated climate regime that permitted the formation of these post-Noachian fluvial landforms, which furthers our understanding of the potential late-stage habitability of Mars.

The area surrounding Lomonosov crater on Mars has a high density of seemingly organised boulder patterns. These form seemingly sorted polygons and stripes within kilometre scale blockfields, patches of boulder strewn ground which are common across the Martian high latitudes. Several hypotheses have been suggested to explain the formation of clastic patterned ground on Mars. It has been proposed that these structures could have formed through freeze-thaw sorting, or conversely by the interaction of boulders with underlying fracture polygons. In this investigation a series of sites were examined to evaluate whether boulder patterns appear to be controlled by the distribution of underlying fractures and test the fracture control hypotheses for their formation. It was decided to focus on this suite of mechanisms as they are characterised by a clear morphological relationship, namely the presence of an underlying fracture network which can easily be evaluated over a large area. It was found that in the majority of examples at these sites did not exhibit fracture control. Although fractures were present at many sites there were very few sites where the fracture network appeared to be controlling the boulder distribution. In general these were not the sites with the best examples of organization, suggesting that the fracture control mechanisms are not the dominant geomorphic process organising the boulders in this area. © 2017 The Authors

The evolution and dynamics of the north-polar cap (residual-ice-cap/layered-deposits complex) of Mars is simulated with a thermomechanical ice-sheet model. We consider a scenario with ice-free initial conditions at 5 Ma before present due to the large obliquities which prevailed prior to this time. The north-polar cap is then built up to its present shape, driven by a parameterized climate forcing (surface temperature, surface mass balance) based on the obliquity and eccentricity history. The effects of different ice rheologies and different dust contents are investigated. It is found that the build-up scenarios require an accumulation rate of approximately 0.15–0.2 mm a−1 at present. The topography evolution is essentially independent of the ice dynamics due to the slow ice flow. Owing to the uncertainties associated with the ice rheology and the dust content, flow velocities can only be predicted within a range of two orders of magnitude. Likely present values are of the order of 0.1–1 mm a−1, and a strong variation over the climatic cycles is found. For all cases, computed basal temperatures are far below pressure melting.

This is a summary of the Group Design Project of the MSc course in Astronautics and Space Engineering in the College of Aeronautics at Cranfield University for the academic year 1997/98. Executive summaries from all the individual reports are contained in an Appendix to this report. The project represents about 8000 hours’ e®ort by the students of the course directed by sta®, and takes the form of a preliminary mission feasibility study. The project was based on ESA’s Mars Express mission. The proposed mission is for a Martian lander composed principally of a rover equipped to search for signs of past or present life on Mars. A controlled descent is required to ensure landing close to sites of particular interest. The surface exploration is planned to last 250 Martian days. A Mars orbiter (also part of the Mars Express mission) is used as a relay for the rover to communicate with Earth. The mission appears feasible as far as the study goes. Topics requiring further study were identified and include thermal design, communications with Earth, achieving the required landing precision, and mobility on the Martian su