Evaluating the hazard from Siding Spring dust: Models and predictions

Abstract:

Long-period comet C/2013 A1 (Siding Spring) will pass at a distance of ~140 thousand km (9e-4 AU) - about a third of a lunar distance - from the centre of Mars, closer to this planet than any known comet has come to the Earth since records began. Closest approach is expected to occur at 18:30 UT on the 19th October. This provides an opportunity for a ``free’’ flyby of a different type of comet than those investigated by spacecraft so far, including comet 67P/Churyumov-Gerasimenko currently under scrutiny by the Rosetta spacecraft. At the same time, the passage of the comet through Martian space will create the opportunity to study the reaction of the planet’s upper atmosphere to a known natural perturbation. The flip-side of the coin is the risk to Mars-orbiting assets, both existing (NASA’s Mars Odyssey & Mars Reconnaissance Orbiter and ESA’s Mars Express) and in transit (NASA’s MAVEN and ISRO’s Mangalyaan) by high-speed cometary dust potentially impacting spacecraft surfaces. Much work has already gone into assessing this hazard and devising mitigating measures in the precious little warning time given to characterise this object until Mars encounter.

In this presentation, we will provide an overview of how the meteoroid stream and comet coma dust impact models evolved since the comet’s discovery and discuss lessons learned should similar circumstances arise in the future.