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.
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.
“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.