When: Thursday 8 December at 14.00
Where: Microsoft Teams – Robert Hooke/Online
Speaker: Lonneke Roelofs (Utrecht University)
Hosted by: Alexander Barrett/Manish Patel
Gullies on Mars come in different shapes and sizes; from classical gully systems on crater walls resembling gully systems on Earth, to the linear gullies on large dune fields that lack an Earth analogue. It has long been hypothesized that Martian gullies were formed by the action of liquids. However, recent activity and new flow deposits have shifted the leading hypothesis from water-based flows to CO2-driven flows, as it is hard to reconcile present activity with the present-day low availability of stable water. Nonetheless, the lack of direct observations of these flows leaves science at a stalemate caused by underdetermination. With small- and medium-scale flume experiments in different Mars chambers we try to resolve this impasse. In these experiments we have created CO2-driven granular flows under Martian atmospheric conditions that run out over distances from 1.5 to 4 meter, under angles as low as 10°. These experiments prove that the sublimation of small amounts of CO2-ice can fluidize sediment and sustain granular flows under Martian atmospheric pressure. During this seminar I will discuss the latest results of our experiments, present ideas on flow dynamics and initiation mechanisms, and examine what implications our results have for surface processes on Mars in the past and on the surface processes on other planetary bodies.
Monday, April 3, 2023 - 14:00 to 15:00