Meteor hurricane at Mars on 2014 October 19 from comet C/2013 A1

Abstract

Comet C/2013 A1 will make a very close approach with the planet Mars on 2014 October 19. For this event, we compute the density of cometary dust particles around the Mars Express spacecraft, in order to assess the real risk for space probes. We also estimate the zenithal hourly rate (ZHR) and discuss observational opportunities for the resulting Martian meteor shower. We find, for a surface of 2.7 m2, that the Mars Express spacecraft will experience approximately 10 impacts from particles larger than 100 μm in size. The fluence per square metre is found to be 3.5 during the encounter. The equivalent ZHR is computed to be ZHR ≃ 4.75 × 109 h−1, making this event the strongest meteor storm ever predicted. We call this event a ‘meteor hurricane’, which we define to be a meteor shower with ZHR exceeding 106 h−1. The event will last approximately 5 h in total, and peak around 20:00 ut (Earth ut time). We call for observations of this unique event by all possible means, but also warn operators of Mars-orbiting spacecraft against the risks of impacts from comet particles larger than 100 μm, with impacts speeds of 57.42 km s−1.