Historic Comet Fly-By Over Mars to Occur Sunday

EDITOR’S NOTE: We preface the following general university news release with comments from Nicholas B. Suntzeff, distinguished professor of physics and astronomy at Texas A&M University and director of the astronomy program:

“Most people have no idea what 87,000 miles really means. It is one-third the distance between the Earth and the Moon and would be really, really close if we were talking about the Earth and not Mars. No historical comet of this size has passed close to the Earth, and it is very unlikely that any comet of this size comes near a planet. But if it does and it hits the planet, the results would be devastating, with an impact of the roughly half-mile diameter comet on the order of a hundred-thousand megatons. Such an impact would produce mega-tsunamis, rapid global cooling, societal disruption and could threaten life.

“This comet, however, will only come close to Mars and will not come close to Earth. But the fact that any comet can come close to a nearby planet should make us heed its warning: We must watch the skies for Near Earth Objects (NEO). Congress has mandated that NASA take this threat seriously, and there are multiple NASA telescopes and satellites that are searching for all such Armageddon NEOs.”

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COLLEGE STATION — On Sunday, a comet will hurl past Mars at extremely close range — only 87,000 miles away — and two rovers that have been on the planet for years will capture once-in-a-lifetime images of the event while under the supervision of a Texas A&M University professor.

Mark Lemmon, associate professor of atmospheric sciences and camera team member, will play a key role operating the cameras on the rovers Opportunity and Curiosity as they snap photos of comet Siding Spring, which will be traveling at 126,000 miles per hour and is about one mile in width.

Lemmon has been part of NASA camera crews for years, especially those involving the Mars rovers Spirit and Opportunity, which landed in 2004, and Curiosity, which landed in 2012. He works closely with fellow scientists at the Jet Propulsion Laboratory in Pasadena, Calif. Some of the images taken by Lemmon have been displayed in the Smithsonian Air and Space Museum exhibit, “Spirit & Opportunity: 10 Years Roving Across Mars.”

Comet Siding Spring — named for the Siding Spring Observatory in New South Wales, Australia, where it was discovered — has been on its current journey for billions of years as it travels to Mars. It’s believed it will likely never return.

Astronomers at first realized the comet could crash into Mars, but further observations showed that it would miss Mars within 87,000 miles. To put that into perspective, our Moon is about 239,000 miles from Earth.

“It will come by very close, so close that several satellites orbiting around Mars have been re-positioned and moved behind the planet for protection as Siding Spring flies by,” Lemmon explained.

“Opportunity and Curiosity are on opposite sides of the planet. Opportunity will take images from the surface in the dawn twilight, hours before the comet buzzes Mars. After the Sun sets on the other side of the planet, Curiosity will take pictures as the comet departs Mars. All of this should happen around 3:30 p.m. Sunday our time.”

Comets are difficult to predict, but images will be returned to Earth over the weekend and into next week. The rover images will be released by NASA to public websites, allowing arm-chair explorers to hunt for the comet along with NASA.

“The comet came from what we call the ‘Oort Cloud,’ which is material left over from when the solar system was first created,” Lemmon added. “This is its first and last time coming close to the Sun before it leaves the solar system.

“We cannot plan missions to comets like this — this one was discovered less than two years ago. It is incredible luck that it is saving us the trouble of going to it, as it flies by Mars which is being explored by 7 active robots. It’s believed Siding Spring is about 4.5 billion years old, so we will be looking at something that is one of the oldest objects in the solar system.

“So this very much is a once-in-a-lifetime event, for us and our rovers.”

For more about the comet, go to http://mars.nasa.gov/comets/sidingspring/.

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Contact: Keith Randall, (979) 845-4644 or keith-randall@tamu.edu or Mark Lemmon at (979) 458-8098 or lemmon@tamu.edu