[no sound] [no sound] >>INTERVIEWER: Mars is facing a close call on Sunday, October 19th, when a rare comet will pass by at an extremely close distance. And here to tell us more about Comet Siding Spring, out of NASA's Goddard Space Flight Center in Greenbelt, Maryland, is Planetary Science Division Director Dr. Jim Green. Thank you for joining us. >>JIM: Thank you. >>INTERVIEWER: What is a comet and why do we study them? >>JIM: Well comets have been looked at for millions of years here on Earth by humans and they're just beautiful objects. They're bright with long tails. And when we look inside them, we see that the nucleus is a dirty snowball, made up of ices and rock, that as it gets close to the Sun, produces these long, beautiful tails. These comets were actually born in the early part of our solar system. They're older than the planet Earth. And interactions with the Earth, they're throwing these comets out for millions of miles, and now we have a wonderful opportunity to see Siding Spring come by into the inner solar system. >>INTERVIEWER: So what makes Comet Siding Spring so special, and will we be able to see it here from Earth? >>JIM: Well Siding Spring is very special because it's coming in from the far reaches of our solar system. It's going to pass right in front of Mars. Mars will be bathed in cometary material. Now what's really great about the comet is we'll have assets like Opportunity and Curiosity on the surface observing the comet. In addition to that, we're going to have our spacecraft, like MAVEN, and Mars Reconnaissance Orbiter, and Mars Odyssey, making observations of the comet as it flies by. >>INTERVIEWER: Is this comet dangerous, and will the satellites orbiting Mars be damaged? >>JIM: The comet is not dangerous, in the sense that our spacecraft will be on the other side of the planet Mars when the dust tail goes by. So we've phased them just right so that they're out of danger. And this is very important because it also enables them to observe the comet before, during, and after this fabulous encounter. [no sound] [no sound] >>INTERVIEWER: Sounds great. Where can we learn more? >>JIM: For more information, please go to mars.nasa.gov. [no sound] >>INTERVIEWER: Great, thank you very much, Dr. Jim Green. >>JIM: You're welcome, thank you. [beep beep... beep beep... beep beep...] [beep beep... beep beep... beep beep...]