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NASA prepares for Comet Siding Spring with plan to protect Mars-orbiting satellites while still gathering awesome science

This Hubble Space Telescope view of Comet 2013 A1 Siding Spring, taken earlier this year, shows the abundant dust and debris already being thrown off the comet's surface. (Credit: NASA, ESA, and J.-Y. Li (Planetary Science Institute))

This Hubble Space Telescope view of Comet 2013 A1 Siding Spring, taken earlier this year, shows the abundant dust and debris already being thrown off the comet's surface. (Credit: NASA, ESA, and J.-Y. Li (Planetary Science Institute))

By Scott Sutherland
Meteorologist/Science Writer
Wednesday, July 30, 2014, 3:56 PM

Later this year, on October 19, Mars will be experiencing a close encounter of the cometary kind. Comet 2013 A1 Siding Spring will be making a very close flyby of the Red Planet, and NASA is taking no chances with its orbiting spacecraft.

While missions on the surface of Mars, like Curiosity and Opportunity, get most of the attention these days, NASA currently has three different satellites orbiting the planet - Mars Express (with the ESA), Mars Odyssey and the Mars Reconnaissance Orbiter - with a fourth arriving towards the end of September - the Mars Atmosphere and Volatile EvolutioN or MAVEN. Any worries of an impact between the comet and the planet were wiped away months ago, so the rovers will be perfectly safe while Siding Spring passes. In fact, they might be treated to some truly spectacular meteor showers on that day. However, in orbit, although it now looks like the comet's nucleus is going to pass far enough away from the planet (about 125,000 kms above the surface), there's still some potential danger.

"The hazard is not an impact of the comet nucleus, but the trail of debris coming from it," Rich Zurek, chief scientist for the Mars Exploration Program at NASA's Jet Propulsion Laboratory, said in a NASA JPL statement. "Using constraints provided by Earth-based observations, the modeling results indicate that the hazard is not as great as first anticipated. Mars will be right at the edge of the debris cloud, so it might encounter some of the particles - or it might not."

Schematic of Comet Siding Spring's discovery, orbit, and flyby of Mars (Credit: NASA/JPL-Caltech)

If the planet does pass through the debris trail, that will put the spacecraft in jeopardy, as they will be pelted with ice and rocky fragments that are travelling at speeds of over 200,000 km/h. To protect against that possibility, NASA will use the planet itself for protection. Since the window of danger is about 20 minutes wide, and has been timed out carefully to about 90 minutes after the closest approach, they have begun a series of special maneuvers for their spacecraft, so that they will be on the opposite side of the planet as the comet passes.

The satellites won't just be cowering from the comet, though. They'll be busy for the entire flyby, taking observations of the comet's nucleus, coma and tail, reading the gases boiled off of it by the heat of the Sun, and studying how the debris interacts with the solar wind and Mars' atmosphere. They may see temperatures changes in the atmosphere and maybe even cloud formations (perhaps noctilucent clouds, which are thought to form from meteorite dust).

In all, this has the potential to become one of the most spectacular events we've ever witnessed in the solar system, but it should be especially useful to scientists. Since this looks like Comet Siding Spring's first journey through the inner solar system, that means that the gases and debris thrown off by it have likely remained undisturbed since the formation of the solar system, billions of years ago. The data collected by the satellites could, according to the JPL statement, "provide a fresh source of clues to our solar system's earliest days."

For more information about Comet Siding Spring and NASA's plans for this incredible encounter, see their website (click here), and check back here, on, for more updates as the day approaches.

STAY TUNED: More Mars stories will be featured on during this unofficial Mars Week here on The Weather Network, leading up to the 2nd anniversary of the Curiosity rover's landing.

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