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collision course a comet heads for mars

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presented by science at nasa

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over the years the space-faring nations

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of earth have sent dozens of probes and

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rovers to explore mars

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today there are three active satellites

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circling the red planet while two rovers

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solar-powered opportunity and

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nuclear-powered curiosity wheel across

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the red sands below

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mars is dry barren and apparently

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hauntingly lifeless

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soon those assets could find themselves

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exploring a very different kind of world

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there is a small but non-negligible

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chance that comet 2013 a1 will strike

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mars next year in october of 2014 says

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don yeomans of nasa's near-earth object

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program at jpl

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current solutions put the odds of impact

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at one in two thousand

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the nucleus of the comet is probably one

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to three kilometers in diameter and it

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is coming in fast around 56 kilometers

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per second

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125 000 miles per hour

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if it does hit mars it would deliver as

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much energy as 35 million megatons of

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tnt estimates humans

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for comparison the asteroid strike that

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ended the dinosaurs on earth 65 million

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years ago was about three times as

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powerful

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100 million megatons

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another point of comparison is the

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meteor that exploded over chelyabinsk

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russia in february of 2013 damaging

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buildings and knocking people down

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the mars comet is packing 80 million

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times more energy than that relatively

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puny asteroid

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an impact wouldn't necessarily mean the

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end of nasa's mars program but it would

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transform the program along with mars

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itself

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i think of it as a giant climate

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experiment says michael meyer lead

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scientist for the mars exploration

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program at nasa headquarters an impact

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would loft a lot of stuff into the

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martian atmosphere

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dust sand water and other debris

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the result could be a warmer wetter mars

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than we're accustomed to today

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meyer worries that solar-powered

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opportunity might have a hard time

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surviving if the atmosphere became

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opaque nuclear-powered curiosity though

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would carry on just fine he also notes

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that mars orbiters might have trouble

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seeing the surface for a while at least

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until the debris begins to clear a

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direct impact remains unlikely

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paul chodus of nasa's near-earth object

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program stresses that a one in two

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thousand chance of impact means there's

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a one thousand nine hundred ninety nine

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in two thousand chance of no impact

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a near miss is far more likely he points

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out

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even a near miss is a potentially big

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event the latest orbit solutions put the

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comet somewhere within 300 000

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kilometers of the red planet at closest

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approach

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that means mars could find itself inside

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the comet's gassy dusty atmosphere

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visually the comet would reach zeroth

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magnitude that is a few times brighter

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than a first magnitude star as seen from

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the red planet

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cameras on all of nasa's spacecraft

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currently operating at mars should be

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able to take photographs of comet 2013

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a1 says jim bell a planetary scientist

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and mars imaging specialist at arizona

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state university

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researchers will be keenly interested to

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see how the comet's atmosphere interacts

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with the atmosphere of mars

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for one thing there could be a meteor

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shower

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another possibility is martian auroras

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unlike earth which has a global magnetic

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field that wraps around our entire

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planet

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mars is only magnetized in patches

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here and there magnetic umbrellas sprout

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out of the ground creating a crazy quilt

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of magnetic poles concentrated mainly in

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the southern hemisphere

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ionized gases hitting the top of the

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martian atmosphere could spark auroras

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in the canopies of the magnetic

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umbrellas

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nasa is sending a new spacecraft to mars

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to study the dynamics of the martian

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atmosphere

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maven is scheduled to launch in november

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2013 and would reach mars just a few

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weeks before the comet in 2014

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however maven's principal investigator

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bruce jokowski of the university of

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colorado notes that the spacecraft won't

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be fully operational and ready to

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observe the comet when it reaches mars

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it takes a while to get into our science

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mapping orbit he explains but he adds

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there are some effects that i would

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expect to linger for a relatively long

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period especially if the comet hits mars

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and we will be able to observe those

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changes

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astronomers around the world are

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monitoring 2013 a1

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every day new data arrive to refine the

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comet's orbit as the error virus shrink

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yeomans expects a direct hit to be ruled

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out the odds favor a flyby not a

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collision he says

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either way this is going to be good