The Siding Spring cometary encounter with Mars: A natural experiment for the Martian atmosphere?

Abstract

On 19 October 2014 comet C/2013 A1 will encounter Mars. The planet is anticipated to pass through the coma resulting in a greater than four order-of-magnitude increase in the accretion of dust with 430 tonnes of dust with diameters between 1 μm and 12.4mm surviving atmospheric passage. At high altitude, the dust would impact temperature and may affect limb dust extinction and cloud formation. The UV photolysis of the organic carbon content of the dust, 1.9 to 4.6 tonnes, would have a negligible effect on atmospheric methane. Should C/2013 A1 brighten, increases in upper atmospheric accretion of coma particles will exceed the background dust and the population of small coma particles may be constrained from orbital measurements. For M 1