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NASA Preparing to “Duck and Cover” for Mars’ Close Encounter with Comet

At just one third the distance of our Moon, Comet Siding Spring (C/2012 A1) is set to pass Mars ten times closer than any recorded comet has ever passed Earth. As NASA currently have two spacecraft orbiting the red planet (and one on the way), cautionary measures are being drafted to manoeuvre the spacecraft (if necessary) out of harms way.

It may not be known for a few months how much of a threat Comet Siding Spring will be, and although its course is now well mapped out, it’s the sheer unpredictability of how active the comet will become that has scientists preparing for the worst case scenario. Between now and May, Siding Spring will draw close enough to the Sun for ice on its surface to start vaporizing and releasing dust particles, these particles drift slowly away from the comet and by October could be abundant and dense enough to envelop Mars as Siding Spring passes by.

Comet Siding Spring's Path

Planning Ahead

“It’s way too early for us to know how much of a threat Siding Spring will be to our orbiters,” JPL’s Soren Madsen, Mars Exploration Program chief engineer, said last week. “It could go either way. It could be a huge deal or it could be nothing — or anything in between.”

“How active will Siding Spring be in April and May? We’ll be watching that,” Madsen said. “But if the red alarm starts sounding in May, it would be too late to start planning how to respond. That’s why we’re doing what we’re doing right now.”

Meanwhile, ground based spacecraft on Mars are hoping to get a glimpse of the comet as it passes 80 times closer than Comet ISON did last year. “We could learn about the nucleus — its shape, its rotation, whether some areas on its surface are darker than others,” said Rich Zurek, Mars Exploration Program chief scientist at NASA’s Jet Propulsion Laboratory. “Our plans for using spacecraft at Mars to observe comet Siding Spring will be coordinated with plans for how the orbiters will duck and cover, if we need to do that.”

Faster than a Speeding Bullet

Orbiting spacecraft are designed to withstand dust particle collisions and most collisions do not damage a mission’s objective. By blanketing vital components in a spacecraft, it lessens the chance of anything important becoming damaged. Comet Siding Spring is travelling in the opposite direction to Mars which means any dust that should hit an orbiter would do so at 50 times the speed of bullet. If enough of these dust particles were to hit an orbiter at this speed over a short period of time, the chances that damage would occur to vulnerable equipment would be significantly high.

Some of the plans to make sure this doesn’t happen involve shielding the spacecraft behind the planet itself or orienting the spacecraft in such a way that vulnerable equipment is pointing away from incoming dust. Of course, the further in advance that these manourverers are planned, the lesser the fuel that will be needed to do so.

The next few months will be vital in assessing how much of a threat Comet Siding Spring will become to spacecraft orbiting Mars, if it rapidly brightens, this will be an indication that the “Duck and Cover” plans will need implementing.

You can keep track of Comet Siding Spring’s current distance from Mars and see an animation on our LIVE data page.

Image credit: Courtesy NASA/JPL-Caltech.