Last year, the web went abuzz when it was announced that a newly found comet, now named Comet Siding Spring, was possibly on a collision course with Mars come October 2014. Although even at the time, the exact odds according to Don Yeomans of NASA's Near Earth Object Program, were only about 1 in 2000, the frenzy continued.
Now, almost exactly a year later, the possibility of an impact is now at zero, the fact that the comet will come within 85,000 miles of Mars is still major news for the space community.
Now, just-released pictures from the Hubble Space Telescope show that the comet has just sprouted a pair of jets that are spewing material out into space.
So, what's going on?
Speaking on these observations, Jian-Yang Li, of the Planetary Science Institute in Tucson, Ariz., said that "this is critical information that we need to determine whether, and to what degree, dust grains in the coma of the comet will impact Mars and spacecraft in the vicinity of Mars." Right now, scientists are not worried about the Curiosity and Opportunity Mars rovers, but are somewhat concerned about satellites orbiting Mars. Come April or May, though, there will be more concrete observations to alleviate, or boost fears, depending on what new discoveries indicate.
Sharing his thoughts on an impact, Michael Meyer, lead scientist for the Mars Exploration Program, said that "I think of it as a giant climate experiment . . . an impact would loft a lot of stuff into the Martian atmosphere--dust, sand, water and other debris. The result could be a warmer, wetter Mars than we're accustomed to today."
Another intriguing possibility: as seen from Mars, the comet will appear very bright, probably around zero magnitude. For scientists working on NASA's current Mars missions, the thought of imaging the comet from Mars is an exciting possibility, albeit one not without problems.
Jim Bell, a planetary scientist and Mars imaging specialist at Arizona State University, spoke on the central problems with imaging a comet from Mars, namely that "the issue with Mars Odyssey and the Mars Reconnaissance Orbiter will be the ability to point them in the right direction; they are used to looking down, not up,” adding that “the issue with the Opportunity and Curiosity rovers will be power for imaging at night . . . Opportunity is solar powered and so would need to dip into reserve battery power to operate the cameras at night . . . on the other hand, Curiosity is nuclear powered, so it could have better odds at night-time imaging.”
Another intriguing possibility is how the cometary and Martian atmospheres will reach, possibly to the tune of Martian aurora. Unlike Earth, Mars only has a patchy magnetic field, which means that, should the comet's atmosphere interact with one of these areas, ionized gasses could react with the Martian atmosphere and spark aurora.
In the end, though, only time will tell what happens. Will the comet hit or merely pass by Mars? Will there be Martian lights? Will our robotic emissaries be able to photograph the event? Right now, no one knows, so stay tuned.
Another question: will the impact (if it even happens) be able to be seen from Earth? Well, possibly. According to NASA, the comet is about a half to one and a half miles across,traveling at about 25 miles per second, and would hit with the force of about 35 million megatons of TNT, or about a third as much force as the impact that wiped out the dinosaurs. Needless to say, the impact, should it take place, would be a big one, an event that could quite possibly, with telescopic aid, be seen from Earth.
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