Active Surface Processes

We study processes that actively shape planetary surfaces today. Using high-resolution orbital, and in situ data, we are able to quantify changes occurring at the metre-scale on Earth and other planetary bodies.

Mars

Mars is not a dead planet. Instead, it is a dynamic world with many surface processes still active today. With the exception of occasional meteorite impacts, all of the changes we observe are driven by the environmental conditions close to the surface. Changes in controlling factors such as atmospheric temperature, pressure, and water content (most as a result of seasonal differences) are thought to be responsible for the processes occurring at the surface today. However, it is also possible that internal processes, such as Marsquakes, are not only occurring today but are also causing changes through faulting at the surface. The NASA InSight mission will be the first mission designed to specifically determine whether there are active Marsquakes today, which can then be used to study the interior structure of Mars.

For the first time, we now have the data and methods necessary to identify and monitor active surface processes from orbital data. Since the arrival of the Mars Reconnaissance Orbiter in 2005, near global coverage of unprecedented resolution has been achieved, offering long-term, repeat coverage of the surface of Mars. Moreover, with the advent of sub-metre resolution, even small-scale surface changes can be identified and large areas examined.

Using a new image analysis approach we have attempted to identify and quantify three different types of active surface process on Mars. First, young fault systems on Mars were studied to determine whether they are active today, by quantifying any surface movement down to the millimetre per year scale. The discovery and analysis of marsquakes using this method offers an important independent and complementary data set to that of the InSight mission. Second, surface deposits that are thought to be rich in ice and similar to glaciers on Earth have been monitored to determine whether they are flowing today. Glaciers can flow in a range of different ways, but most involve at least small amounts of meltwater, which is vital in studies of habitability on Mars. Third, we have monitored many wind-blown deposits such as dunes and ripples, to calculate how fast sand is transported across Mars, which is important in modelling the martian atmosphere and climate and also for the safety and operation of future lander missions.

One of the main advantages of this work is that it uses data from the ESA 2016 Trace Gas Orbiter mission, which not only offers the repeat coverage necessary for the method to work, but also a much longer time-frame over which to monitor these active surface processes.

The Moon

The age of every planetary surface beyond the Earth-Moon system is ultimately derived from the lunar cratering record. Studying the size and density of impact craters on a planetary surface is the only technique to derive an age through remote sensing. The Moon, through samples returned by the Apollo and Luna missions, provides the critical calibration data for the chronology of impact craters throughout the Solar System. So if our understanding of lunar crater chronology is wrong, then our understanding of the age of every planetary surface in the Solar System is also wrong. While the ages of ancient lunar impacts are relatively well understood because they were sampled directly, the age and geological context of younger impact material is controversial to this day. We will use the Apollo 17 landing site as a key to determining whether our knowledge of the last 800 million years of solar system bombardment history is correct, by studying the origin and dynamics of the ‘light mantle’ landslide. By extension, we will detect and quantify a range of active surface processes at the Apollo 17 landing site and also globally on the Moon. This work forms part of our role as Co-Investigators in the NASA Apollo Next Generation Sample Analysis (ANGSA) program.

Earth

There is scientific consensus that humans are changing the climate of the Earth. Moreover, the impact of human activity now extends to almost the entire surface of our planet, causing significant geological change and the definition of a new epoch: “The Anthropocene”. The advent of the space age has allowed Earth observation satellites to provide global coverage of the planet with increasing spatial and temporal resolution. In effect, orbital data are bearing witness to geological processes occurring on human timescales.

The overall aim of this work is to exploit enhanced geological processes on the Earth caused by human activity, to better understand the evolution of Mars. The goal is twofold: (1) to quantify the rate of geological processes enhanced during the Anthropocene Epoch on Earth, in order to (2) investigate the extent and punctuated decline of water throughout the history of Mars. This will be the first to attempt such a novel planetary analogue approach. Specific objectives are the monitoring and study of (1) lake drainage and delta formation, (2) climate change and ice loss, and (3) desertification and dune activity, all on two different planets.