Comet Siding Spring and Mars. Animation of NASA's MAVEN spacecraft and Comet Siding Spring during its encounter with Mars. Comet Siding Spring (C/2013 A1) passed within around 132, 000 kilometres of Mars on 19 October 2014. This was extremely close in planetary terms, and the planet was showered with cometary dust and particles, detected by the orbiting spacecraft. MAVEN (Mars Atmosphere and Volatile Evolution Mission) also detected an intense meteor shower.