Will Mars Be Hit By Comet?

Will a comet strike the planet Mars next year? If id does what does this mean for NASA's Mars Program? Image Credit: NASA
Will a comet strike the planet Mars next year? If it does, what does this mean for NASA’s Mars Program? Image Credit: NASA

We might lose one of the two rovers currently roaming Mars, maybe even one of the orbiters that are presently circling the Red Planet—but not due to age or a technical glitch. A comet, known as Comet 2013 A1, or more commonly as the “Siding Spring Comet,” which is approximately 1–3 kilometers in diameter, is barreling toward Mars at this very moment. It could impact the dusty Martian terrain in October 2014.

While it might be dramatic to imagine one of mankind’s Martian pathfinders snuffed out by a rogue comet, it is also highly unlikely to occur. The odds of the comet striking Mars alone are remote. Estimates coming out of NASA’s Jet Propulsion Laboratory (JPL) put the chances of impact at about 1 in 2,000.

These estimates are from JPL’s Near-Earth-Object Program, the group responsible for tracking wayward leftovers of the solar system’s formation.

“It if does hit Mars, it would deliver as much energy as 35 million megatons of TNT,” said Don Yeomans of NASA’s Near-Earth Object Program at JPL.

Comet 2013 A1 is estimated to be traveling at some 125,000 miles per hour (approximately 56 kilometers per second). This imparts a great deal of energy to the comet, and therefore a great deal of destructive potential as well. This potential energy is what determines how many “megatons” of fury will be brought to bear.

To provide an idea of just how destructive this dirty snowball could be, the asteroid that caused the mass extinction of the dinosaurs some 65 million years ago was about three times as powerful. Mars is about one third the size of the Earth—do the math.


Video Courtesy of ScienceAtNASA

Some models have a warmer, wetter Mars emerging after a possible impact. This would be caused by all of the dust, water, and other particulates tossed up into the Martian atmosphere.

If this were to occur, it would almost undoubtedly spell the end of one of NASA’s longest-serving Martian explorers—the Mars Exploration Rover (MER) Opportunity. Opportunity landed on Mars in 2004 shortly after her sister rover, Spirit. Opportunity is solar-powered, and having the Sun blotted out would probably spell the end of her career.

The other rover operating on Mars, Curiosity, is nuclear-powered and therefore would not be impacted by a lack of sunlight (although it remains to be seen what impact that much matter would do to the signals the rover both sends and receives on a daily basis). In short, the only way that Curiosity could find her time on Mars come to a comet-induced close, is if she were to be in the impact zone.

NASA plans to use the Mars Reconnaissance Orbiter, which is currently circling the Red Planet to conduct science as the comet approaches - and hopefully passes. Image Credit: NASA / JPL
NASA plans to use the Mars Reconnaissance Orbiter, which is currently circling the Red Planet to conduct science as the comet approachesand hopefully passes. Image Credit: NASA / JPL

While this would not necessarily mean the end for NASA’s Mars Program, it would fundamentally alter both it and the planet itself. For their part, NASA representatives are remaining calm about the comet’s upcoming trip to Mars.

“We are mainly looking at the Siding Spring Comet as an opportunity to do some interesting science because of its close approach to Mars. We will get into detailed planning once we have better information about the trajectory and brightness. We expect to observe it with HiRISE and perhaps other instruments in 2014. We are working to get a practice run with comet ISON later this year,” said NASA Deputy Project Scientist on NASA’s Mars Reconnaissance Orbiter team Leslie Tamppari.

NASA’s Mars Reconnaissance Orbiter, or “MRO,” is one of three spacecraft currently in orbit around the Red Planet. It’s suite of scientific instruments have been used to image both a rover and a lander’s descent to the Martian soil. They would now be turned to eye a comet.

As has been the case on Earth lately, there will be just a near-miss. Last month, an asteroid conducted a similar close flyby of our home world. Dubbed 2012 DA14, this piece of space rock passed incredibly close to Earth, closer than some of the satellites that we have orbiting overhead. A close pass, in and of itself, would be stunning as the distance of closest approach (without getting pulled into Mars’ gravity well and striking the planet) is 300,000 kilometers—that places the planet within the long gaseous coma, or “tail,” of the comet.

“Cameras on all of NASA’s spacecraft currently operating at Mars should be able to take photographs of Comet 2013 A1,” said Jim Bell, a planetary scientist who has worked on several missions to Mars. “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. Mission designers will have to figure out if that is possible.”

NASA is preparing to launch its next-generation Mars orbiter, the Mars Atmosphere and Volatile Evolution, or “MAVEN,” in November 2013. It, however, won’t be operational in time to image the Siding Comet’s pass through the Martian system.

Theoretically, the one Mars rover most at risk is the Mars Exploration Rover Opportunity, who will be in her tenth year during the comet's approach. If there were to be an impact - the sun would likely be blotted out and therefore the rover's source of power would be cut off. Image Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ.
Theoretically, the one Mars rover most at risk is the Mars Exploration Rover Opportunity, who will be in her 10th year during the comet’s approach. If there were to be an impact, the Sun would likely be blotted out and therefore the rover’s source of power would be cut off. Image Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ.

“It takes a while to get into our science mapping orbit, deploy the booms, turn on and test the science instruments, and so on,” said MAVEN’s Principal Investigator Bruce Jakosky. “MAVEN won’t be fully operational until perhaps two weeks after the comet passes.  There are some effects that I would expect to linger for a relatively long period—especially if the comet hits Mars—and we will be able to observe those changes.”

Researchers are very interested in seeing how the Martian and cometary atmospheres interact with one another. The comet will be very bright on the Martian surface, reaching a predicted 0th magnitude—brighter than a 1st magnitude star.

Currently, researchers and scientists are studying the models to see by how much the comet will miss Mars—or if it will miss it at all. Generally, determining such things is a very accurate procedure. However, as was the case the day of the close pass of 2012 DA14, surprises happen. On the same day that the asteroid conducted its close pass, another hunk of space debris, a meteorite, slammed into Russia, breaking windows and injuring residents. So we’ll just have to wait and see what takes place with the Siding Spring Comet.

This article was produced using content provided by Science at NASA.



  1. I have no confidence in the ability of NASA to predict any object hitting any planet when they did not see the “100 year event” object hit Russia….

    • This is unfair criticism towards NASA or any other agency for that matter. No one could have ever seen the meteor that hit Russia, because its trajectory showed that it came from the direction of the Sun during daytime. No telescope or earth-bound instrument can observe under these conditions. It’s like humans. Could you stare directly at the Sun at daytime and detect a 15m rock in the same direction at the same time without getting blinded?

      • Great reply thanks for the insight as to what happened….You are the first explanation that I have read from any source…It was not given by the lame stream media…Nor was a solution which based on what you said a pair of observation satellites that operate perpindicular to each other and the sun.

        • Sadly, there is so much misinformation about space subjects on the general media, that is no wonder that people really don’t have a clue as to what is going on in space. If you want to be informed, don’t count on media and TV. You have to start reading and searching for yourself.

          There are instruments and survey programs observing the skies for near-earth asteroids. All these are collectively called ‘Spaceguard’ (an umbrella term). You can look it up on Wikipedia here:


          Actually in the 1990’s, NASA was directed by Congress to discover and catalogue all possible threats from nearby asteroids (NEO’s) bigger than 1 km, and NASA did a very good job. It catalogued approximately 80-90% of them. You can read NASA’s report about the project here:


          The problem is that the detection capability limits (and lack of funding!) were such that only asteroids bigger than 1km could be traced. The one that hit Russia, was only 15-20m long, and it’s calculated that there may be 20.000 more out there with such a samll size. So, no one could have seen the meteor over Russia in advance, even if they wanted to.

          NASA Administrator Bolden, recently testified before Congress about the whole subject, and in essence he said, if you want asteroids to be detected, pay now, or pray later!
          You can watch part of Bolden’s testimony here:


          Hope that helps!

          • Wow….
            I guess we are doomed or perhaps some of those new start up companies that will mine astroids will keep an eye out for the one that gets close enough that they can “capture” for mining and that will be our “failsafe”….Still I am shocked we didn’t see that rock that hit Russia !!! I cannot think of what the damage would have been if it hit the ground and only at 20 meters but at 55kps it had the energy of 500 Hiroshima bombs…It would have ruined everybodies day

            • Yes, if that meteor had hit the ground with that kinetic energy, it would have been a really bad day.

              But the thing is that asteroids and meteors aren’t a sudden and new threat. They didn’t suddenly materialised out of thin air. They have been with us since the birth of the Solar System, and it’s 4.5 billion years-old! It’s just that recent events have made us to suddenly look up and acknowledge their existence. Many small meteors through the years must have fallen in the oceans or in unpopulated areas, where nobody was there to see it. The one above Russia just happened to be over a populated area.

              The point is, that although people should keep a watchfull eye, they should not panic and freak out. All this sudden hysteria about ‘death from the skies’, is just the usual mainstream media sensationalism and fear-mongering.

              It would be better to use our time and resources at discovery efforts and cataloguing (which means we should put our hand in our pocket and reach out for the bucks) than freaking out, thinking we’re doomed.

              If the Universe wants to wipe us out someday, it’ll do it while we’re sleeping, without us ever knowing about it!

  2. The possible comet impact on Mars promises to be a very interesting scientific event even if some of the probes do not survive. It is reminiscent of the comet that struck Jupiter. It would also be fortunate for us Earthlings as Mars would perform a Jupiter-like “cleaning” of this piece of space debris.

  3. You seldom get better odds than 1 in 2000 for such things. It would be a huge benefit if it actually hit mars for both science and public perception.

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