C/2013 A1
Comet Siding Spring as seen by Hubble in March 2014 NASA, ESA, and J.-Y. Li

A comet, dubbed 'C/2013 A1 Siding Spring', is gradually approaching Mars for an extremely rare and close fly-by around the Red Planet later this year.

Expected to fly past Mars on 19 October, the comet has prompted Nasa to shelter its Mars orbiters and rovers from the encounter, which is likely to put on a "barnstorming show" on the planet according to the space organisation.

Dust particles from the comet will hurtle past Mars at 35 miles per second and will have the ability to pierce a hole in the gas line of a spacecraft, or disrupt a computer board. At that velocity they could also crack a glass lens, or take out a few cells on a solar panel.

"They are essentially little cannonballs and bullets flying around, and they could do real damage," Richard Zurek, chief scientist for the Mars Program Office at NASA's Jet Propulsion Laboratory, told the LA Times.

The comet, which was discovered by an Australian comet hunter named Robert McNaught in January 2013 at the Siding Spring Observatory in New South Wales, Australia, will pass Mars at a distance that is 10 times closer to the planet's surface than any identified comet has ever flown past Earth.

At the time of its discovery, Comet Siding Spring was farther from the Sun than Jupiter is, and was about 7.2 times farther away from the sun than Earth, according to Nasa.

It had been part of the icy Oort Cloud at the edge of the solar system for billions of years, before a 'gravity-based shake-up' directed it toward Mars. It has travelled for over one million years to reach the Red Planet.

Nasa plans to gather valuable scientific data on the comet in the days before and after its closest approach, according to Earth Sky.

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