The 'daily grind' - cold mechanochemical reactions on Earth and Mars
- Event time: 1:30pm until 3:00pm
- Event date: 3rd May 2017
- Speaker: Dr Jon Telling
- Location: Room 4325B, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
When early people first struck one flint against another and created a spark, they were inventing the science of mechanochemistry. Mechanochemistry is the science of broken bonds - the breaking of mineral structures to produce free radicals (‘dangling bonds’), and their consequent recombination with other reactants. In the example of striking a flint, freshly formed silica free radicals react swiftly with atmospheric gases to combine nitrogen and oxygen into smelly nitrous oxides, with the release of sufficient energy to light kindling.
My recent research has focused on mechanochemistry in cold environments. On Earth, the crushing of silicate minerals under glaciers and ice sheets produces abundant mineral free radicals that can potentially split water. This can produce hydrogen gas and oxidants that may help sustain subglacial microbial communities on Earth, with potential implications for the habitability of subsurface icy environments on extraterrestrial bodies.
The abrasion of sand grains in aeolian environments can also initiate mechanochemical reactions. Gentle grinding during wind abrasion may react the surfaces of sand grains with methane to form methyl-silica bonds – a novel potential sink and store for methane gas. While on Earth such reactions may be of only minor importance, in the far thinner atmosphere of Mars such reactions could provide globally significant sinks. I’ll describe how such novel mechanochemical reactions provide part of a recent successful UK Space Agency Aurora grant collaborating with two ongoing Mars missions – the recently arrived European Space Agency/Roscosmos ExoMars Trace Gas Orbiter that will map temporal and spatial variations in methane and other trace gases in unprecedented detail, and the ongoing NASA Mars Reconnaissance Orbiter (MRO) orbiter that is mapping patterns of sand movement on Mars.
The astrobiology seminar series is run by the UK Centre for Astrobiology based in the School of Physics & Astronomy. Astrobiology is a multi-disciplinary subject and the seminar series actively encourages attendance by undergraduates, postgraduates and academic staff from other departments..