Debris of 'Doomsday' Comet Elenin to Pass by Earth Sunday (SPACE.com)

The moment long feared by conspiracy theorists is nearly upon us: The "doomsday comet" Elenin will make its closest approach to Earth Sunday (Oct. 16). Or what's left of it will, anyway.

Comet Elenin started breaking up in August after being blasted by a huge solar storm, and a close pass by the sun on Sept. 10 apparently finished it off, astronomers say. So what will cruise within 22 million miles (35.4 million kilometers) of our planet Sunday is likely to be a stream of debris rather than a completely intact comet.

And the leftovers of Elenin won't return for 12,000 years, astronomers say.

"Folks are having trouble finding it, so I think it's probably dead and gone," said astronomer Don Yeomans of the Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif. [Gallery: Comet Elenin in Pictures]

That means it probably won't present much of a skywatching show Sunday, scientists have said.

The doomsday comet

Elenin's apparent demise may come as a relief to some folks, since apocalyptic rumors circulating on the Internet portrayed the comet as a major threat to Earth.

One theory claimed Elenin would set off havoc on Earth after aligning with other heavenly bodies, spurring massive earthquakes and tsunamis. Another held that Elenin was not a comet at all, but in fact a rogue planet called Nibiru that would bring about the end times on Earth. After all, the comet's name could be taken as a spooky acronym: "Extinction-Level Event: Nibiru Is Nigh."

Those ideas were pure nonsense, Yeomans said.

"Elenin was a second-rate, wimpy little comet that never should have been noted for anything, really," he told SPACE.com. "It was not even a bright one."

Elenin's remains will not be the only objects about to make their closest pass of Earth. One day after the Elenin flyby, the small asteroid 2009 TM8 will zip close by. Like Elenin, it poses no risk of striking our home planet.

Asteroid 2009 TM8 is about 21 feet (6.4 meters) wide and the size of a schoolbus. It will come within 212,000 miles of Earth  –  just inside the orbit of the moon  –  when it zips by on Monday morning (Oct. 17).

Say goodbye to Elenin

Elenin was named after its discoverer, Russian amateur astronomer Leonid Elenin, who spotted it in December 2010. Before the icy wanderer broke up, its nucleus was likely 2 to 3 miles (3 to 5 km) in diameter, scientists say.

Elenin never posed any threat to life on Earth, Yeomans said. It was far too small to exert any appreciable influence on our planet unless it managed to hit us.

"Just driving to work every day in my subcompact car is going to have far more of a gravitational effect on Earth than this comet ever will," Yeomans said.

Elenin's supposed connection to earthquakes was just a correlation, and a weak one at that, he added. Relatively strong earthquakes occur every day somewhere on Earth, so it's easy — but not statistically valid — to blame some of them on the comet's changing position.

Yeomans views the frenzy over Elenin as a product of the Internet age, which allows loud and often uninformed voices to drown out the rather more prosaic results that scientists publish in peer-reviewed journals.

"It's a snowball effect on the Web," Yeomans said. "You get one or two folks who make an outrageous claim, and a bunch of others pile on. Some folks are actually making a living this way."

Elenin's crumbs will soon leave Earth in the rear-view mirror, speeding out on a long journey to the outer solar system. But Yeomans doesn't think the departure will keep the conspiracy theorists down for long.

"It's time to move on to the next armageddon," he said.

You can follow SPACE.com senior writer Mike Wall on Twitter: @michaeldwall. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

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NASA: UARS Satellite Debris Poses 1 in 3,200 Chance of Hitting Someone (ContributorNetwork)

NASA's Upper Atmosphere Research Satellite (UARS) will fall to Earth sometime during late September or early October, NASA told reporters today in a teleconference. Atmospheric changes that take place on a daily basis making it impossible to predict exactly where or when it will come down with any real accuracy even as close as two hours prior to the re-entry.

Satellites the size of UARS, on average fall to Earth about once every year and are the subject of detailed break-up analyses by NASA scientists. In this case, NASA expects that UARS will break up in such a way that 26 pieces will strike the ground at speeds ranging from tens of miles per hour to hundreds of miles per hour, according to Nick Johnson of NASA's Orbital Debris Program. In fact, said Johnson, NASA has calculated the odds of any piece of the debris striking a person as 1 in 3200. A number which he says is very, very low and is simply based on the area of possible landfall and global population density.

The re-entry of UARS should be very visible even if it occurs in daylight said Johnson. However, it will b impossible to give enough advance information about where it will re-enter to advise people where and when to look for it. Based on the amount of water versus the amount of land in possible impact field, it is most likely that it will take place out over an ocean and may only be incidentally visible to passing aircraft or ocean vessels.

UARS made a number of important scientific observations over its 14 year effective lifespan including detailed measurement of Earth's atmosphere and of solar radiation. Since 2005, other satellites have replaced its full suite of observational capabilities.

Factbox:

* UARS was built in the 1980's and launched in 1991 at a total cost of $750 million.

* Intact, UARS masses 5.7 metric tons and completely fills the cargo bay of a space shuttle.

* Without NASA intervention, UARS would have remained in orbit until 2025, but its orbital decay was intentionally accelerated by using up all remaining onboard maneuvering propellants in 2005 when it had exhausted its scientific usefulness.

* UARS was the first satellite to record solar flux data over and entire 11 year solar cycle.

* The largest piece of UARS expected to reach the ground masses a little over 300 pounds.

* Other than being struck by fallen debris, NASA says, the biggest risk from the debris is a person getting cut by sharp edges if they try to handle the debris after is has landed. There are absolutely no toxic materials on board, according to Paul Hertz of NASA's Science Mission Directorate.

* All pieces of UARS remain the property of the U.S. government and their location should be made known to local law enforcement officials. Possession or sale of any of the debris by private individuals in the United States is illegal and subject to prosecution.

* In a typical year, 400 pieces of tracked man-made debris re-enters Earth's atmosphere.

* One piece of man-made space debris survives to reach the ground, on average, each week.

* In 2010, approximately 75 metric tons of man-made space debris fell from orbit Earth.

Read more:

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Follow @Space_Matters on Twitter or 'like' the Space Matters Fan Page on Facebook for more of this author's space-related writing.

Brad Sylvester writes about the space program for the Yahoo! Contributor Network. Watching the Apollo missions through the static on a small black and white television sparked a lifelong interest in the space sciences for him. Since then, he has spent 40 years watching improvements in the technologies of space travel and our understanding of the universe.

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Space debris risks colliding with orbital station

The International Space Station is seen with the docked space shuttle Endeavour in this photo provided by NASA and taken May 23, 2011.

Credit: Reuters/NASA/Handout

MOSCOW | Tue Jun 28, 2011 12:01pm EDT

MOSCOW (Reuters) - Six astronauts were forced to take refuge aboard the International Space Station's "lifeboat" crafts on Tuesday, bracing for the threat of a collision with floating space debris, the Russian space agency said.

"A situation arose linked to unidentified 'space trash' passing very close to the space station. The crew was told to take their places aboard the Soyuz spacecraft," Roskomos said in a statement.

The space junk narrowly missed the vulnerable orbiting station by just 250 meters (820 feet) on Tuesday as astronauts were prepared to jump ship, the RIA Novosti news agency cited an official as saying.

It is not the first time space station crews have scrambled for shelter from accumulated space junk. Crews are routinely put on alert to prepare to move out of harm's way.

Three crew members were forced briefly to evacuate the space station in an incident in March 2009.

The station -- a $100 billion project of 16 nations under construction about 220 miles above the earth since 1998 -- is currently manned by three Russians, two Americans and a Japanese astronaut.

Only 10 percent of all objects in Earth's orbit are satellites, while the rest is trash: spent rocket stages, defunct satellites, acceleration blocks and other debris, a spokesman for the agency told state news agency Itar-tass.

Even small objects present a danger to astronauts in orbit, where trash the size of an egg can travel at dangerous speeds.

The minefield of space debris is a growing hazard with ever more satellites in orbit, and one of the most important challenges of future orbital ventures, industry expert Vladimir Gubarev told Reuters.

"Everything is spaced out just some 100 meters from each other. One satellite gets in the way of the next. It's way too crowded," said Gubarev, a renown space journalist and the Soviet spokesman for the joint Apollo-Soyuz mission in 1975.

(Writing by Alissa de Carbonnel; editing by Paul Taylor)

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