Interns from the School of Physics and Astronomy presented their discoveries and insights from the SURE (summer undergraduate research experience) programme for 2022, as reported by Leigh Fletcher.
Every year, the SURE programme provides paid opportunities for talented undergraduates to get a flavour of the cutting-edge research being undertaken within the School of Physics and Astronomy. Projects are offered from across the portfolio of research, ranging from space instrumentation to Earth observation, from planetary exploration to Astrophysics. Eight of eleven students gave talks on their work during hybrid meetings on Tuesday August 30th and Wednesday August 31st 2022.
Samuel Carter (working with Beatriz Sanchez-Cano) used the radar sounder MARSIS on the Mars Express mission to characterise radio bursts at Mars. Mars Express has been operating since 2005, with the MARSIS instrument designed to probe the Martian subsurface and ionosphere, but also providing a tool to track plasma density variations at Mars. A painstaking search through 13 years of data revealed more than 700 radio burst events on the Martian dayside, which became more common during periods of solar maximum. Samuel’s work looked at several examples where solar flares propagated outwards from the Sun, first being detected by Stereo-A (a satellite between Mars and the Sun) before generating the unusual spectrograms detected by Mars Express, providing a new window onto the Sun’s influence at Mars orbit.
Staying with Mars, Niamh Topping (working with John Bridges) used cutting-edge scanning electron microscopes at the University of Leicester to study meteorites from the red planet. In particular, nakhlites are a family of meteorites formed from ancient lava flows at a volcanic site on Mars, then ejected by a large impact, to eventually find their way (coated in a fusion crust) all the way to Earth. Using thin slices of these meteorites, Niamh was looking for evidence of alteration of the igneous rocks by the flow of water – maybe ancient rivers and lakes on the Martian surface. The electron microscopy, coupled with X-ray spectroscopy, produced spectral fingerprints of the elements contained within the meteorites, showing ‘alteration veining’ and the formation of clays within the samples – an excellent way of exploring the history of water on the surface of Mars.
Moving inwards, Mark Sharman (working with Simon Lindsay and Adrian Martindale) had been developing software to help prepare Leicester researchers for the BepiColombo mission to Mercury, and specifically planning for observations from the MIXS X-ray instrument developed here in Leicester. Mercury has been visited only twice, by Mariner 10 and then Messenger. The southern hemisphere in particular remains significantly under-explored. When BepiColombo starts science operations in 2026, MIXS will use x-ray fluorescence of surface minerals to map the composition of the surface, using the MIXS-C instrument for global coverage, and MIXS-T for more targeted observations. Mark developed Python code to understand the coverage of the surface based on a number of different proposed orbital tours, finding plenty of opportunities to study unusual hollows (pitted regions with flat bottoms, maybe due to sublimation of volatiles during surface evolution); bright faculae (volcanic vents, possibly from explosive volcanism), and low-reflectance material that could be evidence of Mercury’s ancient graphite-rich crust.
Two of our summer interns delved into theoretical and numerical simulations of extreme astrophysical events, as a means to understand observed emissions. Peter Gorringe (working with Chris Nixon) explored the disruption of stars by supermassive black holes. A stars pass close to these black holes, within the tidal radius, they can be torn apart by the gravitational forces to generate a debris stream, roughly half of which falls into the black hole, with the rest ejected. These can be very luminous events (detectable in x-rays), with short lifetimes of around 10 years, meaning that they can be observed in their entirety, providing unique insights into how black holes feed and gain mass. Using a hydrodynamical code, Peter simulated the interaction of a binary pair of black holes with the debris of a disrupted star, looking at how the accretion of material depends upon the starting conditions of the simulations (masses, velocities, etc.), and looked ahead to how such simulations might be applied to forthcoming cataloging of tidal disruption events by the Vera Rubin observatory (formerly LSST).
Samuel Tosh (working with Gavin Lamb) continued the theme of high-energy events, this time looking at simulating the light curves of gamma-ray bursts (GRBs), high-energy outbursts whose mechanisms remain a mystery. Samuel converted one potential model (the internal shock model) into a Python simulation, whereby the central engine (e.g., a black hole) ejects matter in shells, each with different masses, widths, and velocities, which then collide with one another to create different shocks, generating radiation via synchrotron emission and inverse Compton scattering. The resulting lightcurves had multiple spikes representing the shocks, and looked similar to x-ray measurements of the GRBs. Having perfected the model, the next step will be to attempt to fit the GRB data to say something about the number of shells and the nature of the central engines.
Closer to home, Jazmin Stewart (working with Steve Leach) looked at improving the efficiency of instrumentation for the detection of Cherenkov radiation, the characteristic blue light created by muon showers resulting from gamma-rays interacting with our atmosphere. The Cherenkov Telescope Array (CTA) aims to observe this radiation as a window on the universe, so the team had Jazmin working on techniques to improve the signal from the individual showers. Using a water bath surrounded by detectors, Jazmin tested a number of wavelength-shifting materials which are designed to transform higher frequencies into lower ones, making them easier to detect. Results for some materials were somewhat unexpected, and surprising amounts of electronic interference were observed in the data, including from mobile phones in the vicinity creating detectable but spurious signals, giving the CTA team plenty of new challenges to consider.
Earth Weather and Telecoms
Two of our interns worked on practical tools with the team at Space Park Leicester that will someday benefit the wider community. Nathaniel McCabe (working with Neil Humpage) was tasked with creating an online weather dashboard for the Space Park Leicester weather station, which has been taking data since July 14th, including the recent heatwave. This application was required to take data from a variety of sources, including ECMWF (the European Centre for Medium-Range Weather Forecasting), the Met Office, DEFRA, and the Copernicus data store (which used the Sentinel satellites), and combine it with data from the SPL weather station. From this vast array of resources, the new application demonstrates meteorological conditions (temperature, humidity, rainfall, pressure), alongside key air quality indicators (such as the pollutants NO2, O3, PM10 and PM2.5, where “PM” is the particulate matter with a particular size distribution in microns). This application will someday be available via the web.
Finally, Thomas Morland-Nuttall has achieved a first for the SURE scheme – he has been working with AST Mobile, a company based at Space Park Leicester. We hope that this scheme can expand in years to come, bringing undergrad students into this amazing new facility. Thomas has been working on simulations of the attenuation of mobile phone signals by ocean waves, with potential application to satellite provision of mobile phone reception to remote locations in the ocean. He explored the influences of diffraction, reflection, and blocking by the geometry of the waves, accessing sea states from ECMWF to generate height maps of the sea surface, to conclude that signal strength could actually be enhanced over water. Such research, using tools and concepts developed during the physics course, could directly benefit AST Mobile in the years to come.
We are proud and grateful to our interns for all their work this summer, and wish them the very best, wherever their careers take them next! Watch this space for opportunities in Summer 2023.