Special APEX seminar 7 Jun: The nature of ejecta blankets formed in small impacts on Mars

We look forward to welcoming visiting speaker, Alex Sokolowska, for a special Astrobiology and Planetary Exploration (APEX) seminar on Wednesday 7th June at 13:00:

• Dr Aleksandra Sokolowska (Brown University) - The nature of ejecta blankets formed in small impacts on Mars 

Abstract

There is ample evidence for water having flowed across the surface of Mars in the past. The data from radar observations, gamma ray/neutron spectroscopy, and the Phoenix lander, point to the possibility that some of this water may be trapped in today's Martian subsurface as ice. However, in general we know very little about the detailed structure or composition of the subsurface. At the same time, meteorite impacts continuously bombard and penetrate the surface, distributing target material laterally to large distances which appear to vary with terrain types. If we leverage the fact that the variations in physical dimensions of craters and ejecta are likely present due to the variations in subsurface properties such as the material strength, and/or volatile concentration, we may open an exciting new window into the nature of the shallow subsurface on Mars. 

In this talk I will discuss two studies. The objective of the first study was to assess whether the spectrum of the most likely martian target materials significantly affects the ballistic emplacement and the spatial distributions of ejecta. I will show numerical models of impact cratering conducted with the hydrocode iSALE on a particular crater scale which is beneath the typical onset crater diameter for producing layered ejecta on Mars and hence small enough to warrant considering ballistic emplacement as the dominant mechanism. This proof of concept study showed promise for using ejecta spatial distributions as subsurface probes in the future. Then I will discuss the applicability of this method to fresh craters on Mars which is the second and ongoing study. Fresh craters on Mars present us with an opportunity to study present substructures up to the depths of meters at many different locations, and the resolution of the HiRISE camera onboard Mars Reconnaissance Orbiter is sufficiently high to enable studies of the details of these fresh strength-dominated impact sites. The main goals of this research theme are to aid the interpretation of remote sensing image data of the impact sites and provide a new independent data type on the subsurface content.

This will be a hybrid event, held in Lecture Theatre G22 on the ground floor of the North West Wing building at UCL. Zoom joining details have been circulated. Please contact Joanna Fabbri if you are not on our regular mailing lists and wish to attend the meetings. As always, everyone interested is welcome to attend. 

Our regular APEX seminars will resume in Autumn 2023/24.

Links 

• Dr Sokolowska's website
• Recordings of previous APEX talks