Don Davis

Artwork by Don Davis shows a meteor streaking over Chelyabinsk. More of Davis' art is on his website.

Now that they've worked out the orbital path of the meteor that blew up over Russia last month, scientists are saying that the asteroid behind the blast crossed Earth's orbit regularly for thousands of years. Two weeks ago, it looked as if the 1.1 million residents of the city of Chelyabinsk had been hit by a cosmic stroke of bad luck — but now they're talking about turning the most powerful asteroid impact in more than a century into a tourist attraction.

The Feb. 15 aerial explosion and the shock wave it set off caused an estimated $33 million in property damage, much of it in the form of shattered windows and weakened walls. It also injured about 1,200 people, with most of them hurt by the flying glass from those windows. Authorities started the cleanup work almost immediately, while researchers rushed to figure out the scale of the explosion.

Based on the readings from infrasound sensors stationed all over the world to monitor nuclear-weapons tests, NASA said the energy release was equivalent to 500 kilotons of TNT, or roughly 30 times the energy released by the atomic bomb dropped on Hiroshima at the end of World War II. That translated into an object about 17 meters (55 feet wide), weighing 10,000 tons. The space agency said it was the biggest cosmic impact recognized since the 1908 Tunguska asteroid blast that leveled millions of trees in Siberia.

Less than a week after the blast, Colombian astronomers worked out a rough orbital path for the Chelyabinsk asteroid, based on an analysis of the videos captured by dashboard cameras and traffic cams in the area. On Friday, NASA produced a more definitive orbital track, based not only on the videos but also on the readings from the federal government's space sensors. The report took advantage of a recently signed agreement with the Air Force Space Command for the public release of previously hush-hush data.

Sizing up a superbolide
Friday's assessment is the first entry in a new NASA database for fireballs and bolide reports, which classifies the Chelyabinsk meteor as a "superbolide."

The latest readings confirm the conclusion that the object's orbit ranged from the main asteroid belt, beyond the orbit of Mars, to well within Earth's orbit. They also show that the Chelyabinsk asteroid's approach couldn't have been detected by ground-based optical telescopes because the space rock was hidden in the sun's glare.

P. Chodas et al. / NASA / JPL-Caltech

An orbital diagram shows the pre-impact orbit of the asteroid that blew up over Russia on Feb. 15, based on the track of its atmospheric entry. The asteroid came at Earth from the sunward side.

"The impactor had likely been following this orbit for many thousands of years, crossing the Earth's orbit every time on its outbound leg," NASA's Near-Earth Object Program Office said in Friday's assessment.

The fresh readings tweaked previous estimates of the object's size and brightness as well: NASA said the meteor was 17 to 20 meters wide (55 to 65 feet wide), and reached peak brightness at an altitude of 14.5 miles (23.3 kilometers), when it was traveling at a speed of 41,760 mph (18.6 kilometers per second). There's also quite a bit of discussion about the energy release — and why the new estimate for impact energy (440 kilotons, which includes energy lost during atmospheric entry) is so much bigger than the fireball's radiated energy (90 kilotons, which applies only to the blast).

From the get-go, astronomers have said that the Russian meteor was not connected with the close flyby of a much bigger asteroid, known as 2012 DA14, which took place later on the same day. Friday's assessment confirms that lack of a connection — not only because the two orbital paths were markedly different, but also because the two asteroids had different compositions.

NASA said a spectral analysis of 2012 DA14, conducted by researchers at the Massachusetts Institute of Technology, suggests that the asteroid is a relatively rare carbonaceous chondrite "with abundant calcium- and aluminum-rich inclusions."

"On the other hand, meteorite fragments being recovered from the fireball event are reported as silicate-rich ordinary chondrites, a completely different and unrelated class of meteorites," NASA said. "About 80 percent of all meteorite falls are in the ordinary chondrite category." 

Andrei Romanov / Reuters

A local resident shows a fragment thought to be part of a meteorite collected in a snow-covered field in the Yetkulski region, outside the city of Chelyabinsk.

Taking pride in a superbolide
Scientists may classify the Russian meteorites as an unremarkable kind of space rock, but they're extra-special to the folks in Chelyabinsk. For one thing, such meteorites could be worth more than their weight in gold on the collectors' market. Some have estimated their value at $2,200 per gram. For another thing, the region's residents are now talking about capitalizing on the international interest generated by the impact.

"Space sent us a gift, and we need to make use of it," Natalia Gritsay, head of the region’s tourism department, told Bloomberg News this week. "We need our own Eiffel Tower or Statue of Liberty."

Among the ideas being debated: building a "Meteor Disneyland" theme park that re-creates the glass-shattering event, or organizing a cosmic music and fireworks festival, or erecting a beacon-tipped pyramid at nearby Chebarkul Lake, where meteorite fragments have been found. Tourist companies are already starting to sell group tours to Chelyabinsk at $800 a person, Bloomberg News reported.

When the meteor exploded, many of the region's residents feared that it was a plane crash, or a missile strike, or even the end of the world. Now it's starting to look as if the superbolide is the best thing to hit Chelyabinsk in years.

“Nobody had heard about us, and now all the world knows,” the region's governor, Mikhail Yurevich, told Bloomberg News. “We can earn some dividends on that."

Slideshow: Meteor streaks over Siberia

Yekaterina Pustynnikova / Chelyabinsk.ru via AP

Click through scenes from Russia's Chelyabinsk region, where a huge meteor fireball set off alarms, injured hundreds of people and caused a factory roof to collapse.

Launch slideshow

More about the meteor:

• Experts get set for the next asteroid
• How to 'hear' the Russian meteor
• NBCNews.com archive on asteroids

Tip o' the Log to space illustrator Don Davis and Spike MacPhee.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

The meteor that blew up over the Russian city of Chelyabinsk 11 days ago has provided a new focus for the effort to establish an international asteroid warning system, one of NASA's top experts on the issue says.

Lindley Johnson, the executive for the Near Earth Object Observation Program at NASA Headquarters in Washington, said that the Feb. 15 impact is certain to become "by far the best-documented meteor and meteorite in history" — but at the time, he and his colleagues could hardly believe it was happening.

"Our first reaction was, 'This can't be. ... This must be some test of a missile that's gone awry,'" Johnson told NBC News.

The Chelyabinsk meteor exploded at an estimated altitude of 12 miles (20 kilometers) over the city of 1.1 million in Russia's Urals Mountains, setting off a shock wave that blew out windows, caused an estimated $33 million in property damage and injured more than 1,200 people.

It was doubly coincidental for Johnson and his colleagues: The meteor was thought to have been caused by the breakup of a 17-meter-wide (55-foot-wide), 10,000-ton asteroid that entered Earth's atmosphere and released the equivalent of 500 kilotons of TNT in explosive energy. All this happened just hours before a 45-meter-wide (150-foot-wide) asteroid, capable of setting off a city-killing blast, passed within 17,200 miles (27,680 kilometers) of our planet. Adding to that coincidence, researchers from around the world were gathered in Vienna for talks aimed at moving forward with an international network to deal with ... asteroid threats!

The spectacle in Russia "certainly brought renewed interest to our efforts here," said Johnson, a leader of NASA's delegation to the Vienna talks.

He said the recommendations from the researchers were "well-received" and are moving up the ladder to the next phase in a U.N.-led process for addressing outer-space threats. An action plan could be considered by the U.N. Committee on the Peaceful Uses of Outer Space during its next meeting in Vienna in June.

Johnson summarized the three main points of the recommendations:

• Set up an international asteroid warning network, or IAWN, supported with existing detection assets but incorporating additional contributions. "The basis of such a network already exists," Johnson said, thanks to NASA, the European Space Agency, the International Astronomical Union's Minor Planet Center and the NEODyS asteroid-tracking center at the University of Pisa in Italy. NASA also has partnered with the U.S. Air Force to share tracking data about near-Earth objects. Just this week, a $25 million Canadian-built satellite known as NEOSSat was launched to look for small asteroids in Earth-threatening orbits.
• Bring the world's space agencies together in a new working group called the Space Mission Planning and Advisory Group — also known as SMPAG (pronounced like "Same Page"). The group's purpose, Johnson said, would be to "get all the agencies on the 'same page' as far as assessing what capabilities could be brought to bear should there be a threatening asteroid detected."
• Put asteroid experts in contact with countries around the world, to advise disaster response agencies about the nature of a potential impact event — that is, the area expected to be affected, the potential effects and the scale of the evacuation if necessary. "It's an offshoot of the warning network," Johnson said. If the asteroid behind the Russian meteor had been detected in advance, for example, the expert network might have advised emergency workers about the potential for a midair blast and the resulting shock wave (although Johnson said he was "surprised" by the shock wave's effect).

Until last year, NASA spent about $4 million a year to track near-Earth objects, or NEOs, and Johnson said the program "has accomplished quite a bit in the relatively short time that it's been in existence." About 95 percent of the potentially threatening asteroids bigger than a kilometer (half-mile) wide have been detected. However, now NASA is working on charting the asteroids down to a width of 100 meters (330 feet). To fund that more difficult task, the annual funding level for NEO research was raised to $20 million a year.

NASA is using that money to beef up its capabilities for spotting smaller asteroids, through programs such as the Asteroid Terrestrial-impact Last Alert System, or ATLAS, which is due to get $5 million over the next five years. Less than a million dollars a year is going toward studies aimed at figuring out what to do if a threatening asteroid is found, Johnson said. After all, you have to identify the risky rocks before you can do anything about them. The potential strategies range from diverting it gently with the aid of gravity tractors or space paintball guns, to blasting it with nukes, Bruce Willis-style.

"It really depends on the scenario that we'd be faced with," Johnson said. "It depends on how big the object is. It depends on how long we have to do something about it. And if we do the search-and-detection job right, we will find a potential hazard many years if not decades before it becomes an immediate threat. There may be technologies available at that time that we never thought about. I don't get too worked up about trying to find an immediate technology that we've got to have right now to do that. Our focus is to find them as early as we can, and have the maximum amount of time to do something about it."

Update for 7:30 p.m. ET Feb. 26: Looking for a practical tip? The large majority of the people injured by the meteor blast were hurt by flying glass, which led Johnson to give this advice during a Vienna news conference: "When you see a white flash and a large trail in the sky, it's probably not a good time to stand at the window and look at it, because it may be a blast coming."

Update for 8:15 p.m. ET Feb. 26: As reported in Technology Review's Physics arXiv Blog, Colombian researchers used video from dashboard cameras and other sources to reconstruct the orbital path of the Russian meteor — and they classified it as an Apollo asteroid, a type of space rock whose path crosses Earth's orbit. That's consistent with NASA's analysis, which said the asteroid traced an orbit that ranged between the main asteroid belt and the region of outer space inside Earth's orbit.

"The preliminary orbit indicates it takes about 2.1 years to go around the sun once ... so this thing was out at its farthest distance from the sun roughly a year ago," Bill Cooke, head of the Meteoroid Environments Office at NASA's Marshall Space Flight Center, told reporters during a Feb. 15 teleconference.

The space rock was on its way back out toward the main asteroid belt, coming from Earth's sunward side, when it entered the atmosphere and blew up. That's why it wasn't possible to predict the impact in advance: At a width of 55 feet, the object was too small to show up in traditional sky surveys, and it would have been lost in the sun's glare during its final approach.

So far, searchers have recovered just bits and pieces of the shattered space boulder. "The largest I've heard is a kilogram and a half," or about three pounds, Johnson told NBC News. 

Slideshow: Meteor streaks over Siberia

Yekaterina Pustynnikova / Chelyabinsk.ru via AP

Click through scenes from Russia's Chelyabinsk region, where a huge meteor fireball set off alarms, injured hundreds of people and caused a factory roof to collapse.

Launch slideshow

More about asteroids:

• How about blasting 'em with lasers?
• How to 'hear' the Russian meteor
• Asteroids vs. comets: Threats compared
• NBCNews.com archive on asteroids

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

This story was originally published on Tue Feb 26, 2013 6:23 PM EST