Mars has intrigued sky gazers for centuries but now seismology, imaging and surface exploring has rapidly increased our knowledge of this neighbouring planet.
Much smaller than the earth [half the diameter and only 10% of the mass} and having lost most of its atmosphere, it gives us a contrasting geological evolution and the tantilising thought that it could have had some life-form and might just retain some evidence of that.
Its southern hemisphere is heavily crated some with features like slumping and various ejectile patterns. The northern part looks much smoother but the consensus is that it too is heavily cratered but these have been mainly obscured by subsequent weathering deposits. An impact in December 2021 generated a crater 750m across.
Vulcanicity certainly gave rise to massive shield volcanoes and very large calderas which in turn show landslip and other process features. Basaltic rocks predominate but with lots of iron and magnesium elements the chemical weathering of which gives the planet its characteristic red image. Vesicular lava forms part of the samples collected by the recent rover.
Images of faceted rocks show the power of wind erosion albeit at a very slow rate. Likewise both linear and barchen sand dunes probably only move 1 or 2 metres a year. Water may have featured both creating alluvial fans within craters and indeed generating an ocean with multiple shorelines. Even stranger is the evidence for tsunamis being generated by large objects from space crashing into and melting a frozen ocean.
Polar ice caps existed and have left unusual spindle and Swiss cheese patterned features. Might there be fossilised life evidence here too?
Seismology instruments on the Insight Lander have detected 1300 marsquakes up to Richter scale 5. The presence of fault features also may imply internal magma movements still continue.
Altogether Keith ably demonstrated for us how much has been learnt recently about this fascinating planet.
Some group activities and meetings are held at Ty Price, St Thomas Community Hall, St Thomas’s Square. There is no off street parking here. The approach on foot is a gentle slope to double entrance doors. The ground floor of the building is fully accessible and there is a disabled toilet. The stairs to the first floor are wide and well-lit with a handrail on both sides, but there is no lift. There is a hearing induction system on the ground floor.