How London's super sewer led to the EnVISION mission to Venus
Interferometry from radar satellite systems, which 30 years ago so dramatically revealed ground movements associated with the Landers earthquake, has evolved into a routine ground engineering monitoring tool able to measure the subtle movements caused by tunnelling and dewatering. At up to 90 metres deep, London's Tideway Tunnel provided the perfect opportunity to test the limits of the technique. The results proved stunningly far from mundane, identifying ongoing geological fault movements an order of magnitude smaller than ever previously measured, just 1 mm/yr, in a location where such movements were completely unexpected and yet entirely predictable. Moreover, they demonstrated that here was a tool capable of determining from orbit whether Venus is as active as Earth, as dead as Mars, or somewhere in between, and so key to understanding why our 'twin' planet is so different to our own. The discoveries in London also reveal a new way of understanding the geology of our nearest neighbour that resolves the paradox of its impact crater distribution. This talk discusses how EnVision overcame technical challenges and overturned a geological paradigm to win the M5 selection.
Prof. Richard Ghail is a Professor in the Department of Earth Sciences of the Royal Holloway University of London. Richard specializes in intra-plate tectonics on Earth and Venus uses radar interferometry (InSAR) to measure fault movements on exceedingly small scales of millimetres per year. He applies the technology to monitoring the surface effects of engineering in the ground and to understanding impact of intra-plate deformation on civil engineering infrastructure, particularly tunnels. He founded the Engineering Scale Geology Research Group to develop these ground investigation techniques and advance their study. Richard proposed Envision and led the ESA science study up to its selection. The mission will apply many of the InSAR technologies and techniques developed for ground engineering to characterise and measure geological activity on Venus.
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