Yesterday the comet C/2013 A1, also known as Siding Spring, passed very close to Mars. The distance from the planet was as low as about 140,000 km (about 87,000 miles), one third of the distance of the Moon from Earth, very close in astronomical terms. The event was followed by several telescopes but nearby ther was was the Earth’s “star fleet” consisting of NASA’s probes and rovers, ESA’s Mars Express probe and the Indian MOM – aka Mangalyaan – probe.