[meteorite-list] Could a Comet Hit Mars in 2014? (Comet C/2013 A1)

[Ron Baalke]

http://www.space.com/20045-comet-hit-mars-2014.html

Could a Comet Hit Mars in 2014?
Ian O'Neill
Discovery News
March 4, 2013

A recently discovered comet will make an uncomfortably-close planetary flyby 
next year - but this time it's not Earth that's in the cosmic crosshairs.

According to preliminary orbital prediction models, comet C/2013 A1 will buzz 
Mars on Oct. 19, 2014. The icy interloper is thought to originate from the 
Oort Cloud - a hypothetical region surrounding the solar system containing 
countless billions of cometary nuclei that were outcast from the primordial 
solar system billions of years ago.

We know that the planets have been hit by comets before (re: the massive Comet 
Shoemaker-Levy 9 that crashed into Jupiter in 1994) and Mars, in particular, will 
have been hit by comets in the past. It's believed Earth's oceans were created, 
in part, by water delivered by comets - cometary impacts are an inevitable part 
of living in this cosmic ecosystem.

C/2013 A1 was discovered by ace comet-hunter Robert McNaught at the Siding Spring 
Observatory in New South Wales, Australia, on Jan. 3. When the discovery was made, 
astronomers at the Catalina Sky Survey in Arizona looked back over their 
observations to find "prerecovery" images of the comet dating back to Dec. 8, 2012. 
These observations placed the orbital trajectory of comet C/2013 A1 through Mars 
orbit on Oct. 19, 2014.

Could the Red Planet be in for a potentially huge impact next year? Will Mars 
rovers Curiosity and Opportunity be in danger of becoming scrap metal?

It seems the likelihood of an awesome planetary impact is low - for now.

According to calculations by NASA's Jet Propulsion Laboratory (JPL), close approach 
data suggests the comet is most likely to make a close pass of 0.0007 AU (that's 
approximately 63,000 miles from the Martian surface). However, there's one huge 
caveat.

Due to uncertainties in the observations - the comet has only been observed for 
74 days (so far), so it's difficult for astronomers to forecast the comet's 
precise location in 20 months time - comet C/2013 A1 may fly past at a very 
safe distance of 0.008 AU (650,000 miles). But to the other extreme, its orbital 
pass could put Mars directly in its path. At time of Mars close approach (or 
impact), the comet will be barreling along at a breakneck speed of 35 miles per 
second (126,000 miles per hour).

Also, we don't yet know how big comet C/2013 A1 is, but comets typically aren't 
small. If it did hit, the impact could be a huge, global event. But the comet's 
likely location in 2014 is also highly uncertain, so this is by no means a 
"sure thing" for Mars impact (Curiosity, you can relax, for now).

One thing is looking likely, however. Mars could be in for its own "cometary 
spectacular."

A flyby of that distance will mean that should C3/2013 A1 erupt with a tail and 
coma around its nucleus (as it becomes heated by solar radiation), our Mars 
rovers and orbiting armada of planetary observation satellites will have a very 
intimate view of this historic moment. It has the potential to be a more impressive 
sight than Comet ISON's inner-solar system trek later this year. But understanding 
the nature of comets is hard to predict; we won't know if the sun's heating 
will be sufficient enough for the comet nucleus to erupt and start out-gassing 
for some time to come.