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Posted: 27-02-2013 00:13 Post subject:

Russia meteor's origin tracked down
By Paul Rincon, Science editor, BBC News website

Astronomers have traced the origin of a meteor that injured about 1,000 people after breaking up over central Russia earlier this month.
Using amateur video footage, they were able to plot the meteor's trajectory through Earth's atmosphere and then reconstruct its orbit around the Sun.
As the space rock burned up over the city of Chelyabinsk, the shockwave blew out windows and rocked buildings.
The team, from Colombia, has published details on the Arxiv website.

Numerous videos of the fireball were taken with camera phones, CCTV and car-dashboard cameras and subsequently shared widely on the web. Furthermore, traffic camera footage of the fireball had precise time and date stamps.

Early estimates of the meteor's mass put it at ten tonnes; US space agency Nasa later estimated it to be between 7,000 and 10,000 tonnes. Nasa estimates the size of the object was about 17m (55ft).

Using the footage and the location of an impact into Lake Chebarkul, Jorge Zuluaga and Ignacio Ferrin, from the University of Antioquia in Medellin were able to use simple trigonometry to calculate the height, speed and position of the rock as it fell to Earth.

To reconstruct the meteor's original orbit around the Sun, they used six different properties of its trajectory through Earth's atmosphere. Most of these are related to the point at which the meteor becomes bright enough to cast a noticeable shadow in the videos.
The researchers then plugged their figures into astronomy software developed by the US Naval Observatory.
The results suggest the meteor belongs to a well known family of space rocks - known as the Apollo asteroids - that cross Earth's orbit.

Of about 9,700 near-Earth asteroids discovered so far, about 5,200 are thought to be Apollos. Asteroids are divided into different groups such as Apollo, Aten, or Amor, based on the type of orbit they have.

Dr Stephen Lowry, from the University of Kent, said the team had done well to publish so quickly.
"It certainly looks like it was a member of the Apollo class of asteroids," he told BBC News.
"Its elliptical, low inclination orbit, indicates a solar system origin, most likely from the asteroid belt between Mars and Jupiter.
Dr Lowry added: "Perhaps with more data, we can determine roughly where in the asteroid belt it come from."

http://www.bbc.co.uk/news/science-environment-21579422

Hmm...

This could be possible (and these people have more data than I have), but it's not clear from the diagram or the text whether the meteor struck from a sunward direction, as I initially surmised. (Generally speaking, an Apollo asteroid would not approach from sunward.)

Posted: 27-02-2013 17:02 Post subject:

That muthafuckin meteor was muthafuckin 17 meter wide, which means it really was a muthafuckin asteroid!

http://www.troll.me/images/angry-samuel-l-jackson/muthafucka.jpg

Posted: 01-03-2013 23:30 Post subject:

Couldn't find any reports of this on FTMB, so I'm posting it here
http://www.ibtimes.co.uk/articles/441162/20130301/russia-meteor-ufo.htm

Russia Meteor: Did UFO stop disaster by blowing up meteor?
In a twist to the Urals meteor strike in Russia, new footage has sparked claims that the space rock was blown up by a UFO.
In reports from the remote part of Russia where the meteor exploded in February, ufologists claimed they have discovered video evidence that shows the rock being struck by an object before it exploded.
There is video as well

Posted: 04-03-2013 20:41 Post subject:

Horizon - 2013-2014 - 1. The Truth About Meteors: A Horizon Special

On a bright, cold morning on 15th February 2013, a meteorite ripped across the skies above the Ural mountains in Russia, distintegrating into three pieces and exploding with the force of 20 Hiroshimas. It was a stark reminder that the Earth's journey through space is fraught with danger. A day later another much larger 14,3000 tonne asteroid, passed within just 17,000 miles of the Earth.

Presented by Professor Iain Stewart, this film explores what meteorites and asteroids are, where they come from, the danger they pose, and the role they have played in Earth's history.

http://www.bbc.co.uk/iplayer/episode/b01r6dys/Horizon_20132014_The_Truth_About_Meteors_A_Horizon_Special/

Available until
10:59PM Thu, 11 Apr 2013

Posted: 04-03-2013 22:01 Post subject:

I enjoyed that. It showed clearly that, although the Chelyabinsk object was on a Apollo type orbit, it hit the Earth coming from inside the Earth's orbit, ie "out of the sun", where things are difficult to detect, even if they're much bigger.

But I was disappointed to hear yet again the idea that blowing up an approaching asteroid with a bomb is a No-No - "The Earth would then get hit by a load of fragments instead!"

But I've never heard this argued in detail. As it's well known that smaller objects burn up in the atmosphere, it seems to me that a cloud of fragments must be less dangerous than a single Earth impactor, because most of the fragments would never reach the surface, and those that did would be eroded in the atmosphere and thus far smaller and less dangerous when they did hit land (although the chances are they'd land in the sea instead).

If it's a choice between an impact that could wipe out half the planet, and a few minor strikes that might take out a city or two, I say "Bomb the m*therf*cker to hell!" Twisted Evil

Posted: 04-03-2013 22:10 Post subject:

I think the only way of finding out what would happen if exploding an asteroid, is to actually do it. Until then we can never know.

My own favoured method is to cover an asteroid in a super-strong net and attach lots of rocket thrusters. The net would keep the asteroid together for just long enough while the rockets change the asteroid's path.

Posted: 05-03-2013 20:19 Post subject:

Posted: 18-05-2013 09:44 Post subject:

1998 QE2: Massive Asteroid to Make 'Royal' Flyby
May 17, 2013 11:41 AM ET // by Mike Wall, Space.com

A big asteroid will cruise by Earth at the end of the month, making its closest approach to our planet for at least the next two centuries.

The May 31 flyby of asteroid 1998 QE2, which is about 1.7 miles (2.7 kilometers) long, poses no threat to Earth. The space rock will come within 3.6 million miles (5.8 million km) of our planet — about 15 times the distance separating Earth and the moon, researchers say.

But the close approach will still be dramatic for astronomers, who plan to get a good look at 1998 QE2 using two huge radar telescopes — NASA's 230-foot (70 meters) Goldstone dish in California and the 1,000-foot (305 m) Arecibo Observatory in Puerto Rico.

"Whenever an asteroid approaches this closely, it provides an important scientific opportunity to study it in detail to understand its size, shape, rotation, surface features and what they can tell us about its origin," Lance Benner of NASA's Jet Propulsion Laboratory in Pasadena, Calif., principal investigator for Goldstone radar observations, said in a statement.

"We will also use new radar measurements of the asteroid's distance and velocity to improve our calculation of its orbit and compute its motion farther into the future than we could otherwise," Benner added.

Asteroid 1998 QE2 was discovered in August 1998 by astronomers working with MIT's Lincoln Near Earth Asteroid Research (LINEAR) program in New Mexico.
The space rock's name is not an homage to England's Queen Elizabeth II, or to the famous 12-deck ocean liner that was retired from service in 2008. It's just the moniker assigned by the Minor Planet Center in Cambridge, Mass., which names each newfound asteroid according to an established alphanumeric scheme that lays out when it was discovered.

Astronomers plan to study 1998 QE2 intensively from May 30 through June 9, using the Goldstone and Arecibo dishes to learn as much as possible about the asteroid before it slips off once more into the depths of space.

Even from about 4 million miles (6.4 million km) away, Goldstone images may be able to resolve features on 1998 QE2 as small as 12 feet (3.75 m) across, researchers said.
"It is tremendously exciting to see detailed images of this asteroid for the first time," Benner said. "With radar we can transform an object from a point of light into a small world with its own unique set of characteristics. In a real sense, radar imaging of near-Earth asteroids is a fundamental form of exploring a whole class of solar system objects."

NASA leads the global effort to identify potentially dangerous asteroids. Our planet has been pummeled by space rocks throughout its 4.5-billion-year history, and more strikes are in our future.

The planet got a dramatic reminder of this reality this past Feb. 15. On that day, a 55-foot (17 m) object exploded without warning over Russia, just hours before the 130-foot asteroid 2012 DA14 gave Earth a close shave, missing our planet by just 17,200 miles (27,000 km).

http://news.discovery.com/space/asteroids-meteors-meteorites/asteroid-flyby-1998-qe2-130517.htm

Posted: 31-05-2013 20:46 Post subject:

A reminder about QE2:

Asteroid 1998 QE2 set for Earth fly-by
By Rebecca Morelle, Science reporter, BBC World Service

An asteroid that measures nearly 2.7km (1.7 miles) across is set to fly past the Earth.
The space rock, which is called 1998 QE2, is so large that it is orbited by its own moon.

It will make its closest approach to our planet at 20:59 GMT (21:59 BST), but scientists say there is no chance that it will hit.
Instead it will keep a safe distance - at closest, about 5.8 million km (3.6 million mi).

That is about 200 times more distant than the asteroid "near-miss" that occurred in February - but Friday's passing space rock is more than 50,000 times larger.

Prof Alan Fitzsimmons, an astronomer at Queen's University Belfast, said: "It's a big one. And there are very few of these objects known - there are probably only about 600 or so of this size or larger in near-Earth space.
"And importantly, if something this size did hit us one day in the future, it is extremely likely it would cause global environmental devastation, so it is important to try and understand these objects."

This fly-by will give astronomers the chance to study the rocky mass in detail.
Using radar telescopes, they will record a series of high-resolution images.
They want to find out what it is made of, and exactly where in the Solar System it came from.

Prof Fitzsimmons said: "We already know from the radar measurements, coupled with its brightness, that it appears to be a relatively dark asteroid - that it's come from the outer part of the asteroid belt."

Early analysis has already revealed that the asteroid has its own moon: it is being orbited by another smaller piece of rock that is about 600m (2000ft) across.
About 15% of asteroids that are large are "binary" systems like this.

This celestial event will not be visible to the naked eye, but space enthusiasts with even a modest telescope might be able to witness the pass.

After this, asteroid 1998 QE2 will hurtle back out into deep space; Friday's visit will be its closest approach for at least two centuries.

Researchers are becoming increasingly interested in potential hazards in space.
So far they have counted more than 9,000 near-Earth asteroids, and they spot another 800 new space rocks on average each year.

http://www.bbc.co.uk/news/science-environment-22736709

Posted: 28-06-2013 08:26 Post subject:

Russian meteor shockwave circled globe twice
By Simon Redfern, Reporter, BBC News

The shock wave from an asteroid that burned up over Russia in February was so powerful that it travelled twice around the globe, scientists say.
They used a system of sensors set up to detect evidence of nuclear tests and said it was the most powerful event ever recorded by the network.
More than 1,000 people were injured when a 17m, 10,000-tonne space rock burned up above Chelyabinsk.
The study appears in the journal Geophysical Research Letters.

The researchers studied data from the International Monitoring System (IMS) network operated by the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO).
The detection stations look out for ultra-low frequency acoustic waves, known as infrasound, that could come from nuclear test explosions. But the system can also detect large blasts from other sources, such as the Chelyabinsk fireball.

Alexis Le Pichon, from the Atomic Energy Commission in France and colleagues report that the explosive energy of the impact was equivalent to 460 kilotonnes of TNT. This makes it the most energetic event reported since the 1908 Tunguska meteor in Siberia.

Meanwhile, another team of scientists has published a study focusing on the Tunguska event.
The 1908 fireball, the biggest space impact of modern times, was probably caused by an iron-rich meteorite, a study in the journal Planetary and Space Science has confirmed.

The Tunguska air blast is estimated to have been equivalent to three to five megatonnes of TNT, hundreds of times more energetic than the Hiroshima explosion, and it flattened trees across 2,000 sq km of forest.

Victor Kvasnytsya, from Ukraine's National Academy of Sciences, and colleagues studied microscopic samples of mineral debris from the blast area that have been trapped in peat.
In their paper, they describe the mineralogy of samples recovered from the peat in the 1970s and 80s. High-resolution imaging and spectroscopy identified carbon minerals such as diamond, lonsdaleite and graphite.

Lonsdaleite in particular is found in carbon-rich material subjected to a shock wave, and is typically formed in meteorite impacts.
The lonsdaleite fragments contain smaller inclusions of iron sulphides and iron-nickel alloys, troilite and taenite, which are also characteristic meteorite minerals.

The iron to nickel ratio and the precise combinations of minerals assembled in these small fragments all point to a meteorite source, and are nearly identical to similar minerals found in the Canyon Diablo meteor that impacted Barringer Crater (Meteor Crater) in Arizona.

The findings would appear to rule out a theory that the Tunguska airburst was caused by a large fragment of Comet Encke. This comet is responsible for a meteor shower called the Beta Taurids, which cascade into Earth's atmosphere in late June and July - the time of the Tunguska event.

http://www.bbc.co.uk/news/science-environment-23066055

Posted: 13-07-2013 22:25 Post subject:

Posted: 01-08-2013 21:52 Post subject:

Not a near miss, but not that far back in time either.

Ice core data supports ancient space impact idea
By Simon Redfern, Reporter, BBC News

New data from Greenland ice cores suggest North America may have suffered a large cosmic impact about 12,900 years ago.
A layer of platinum is seen in ice of the same age as a known abrupt climate transition, US scientists report.
The climate flip has previously been linked to the demise of the North American "Clovis" people.

The data seem to back the idea that an impact tipped the climate into a colder phase, a point of current debate.
Rapid climate change occurred 12,900 years ago, and it is proposed that this is associated with the extinction of large mammals such as the mammoth, widespread wildfires, and rapid changes in atmospheric and ocean circulation.

All of these have previously been linked to a cosmic impact, but the theory has been hotly disputed due to lack of clear evidence.
New platinum measurements were made on ice cores that allow conditions 13,000 years ago to be determined at a time resolution of better than five years, report Michail Petaev and colleagues from Harvard University. Their results are published in the journal Proceedings of the National Academy of Sciences.

A 100-fold spike in platinum concentration occurs in ice that is around 12,890 years old, at just the same moment that rapid cooling of the climate is indicated from oxygen isotope measurements, at the start of a climatic period called the "Younger Dryas".
The Younger Dryas started and finished abruptly, and is one of a number of shorter periods of climate change that appear to have occurred since the last glacial maximum of 20,000 years ago.

Each end of the Younger Dryas period may have involved very rapid changes in temperature as the climate system reached a tipping point, with suggestions that dramatic changes in temperature occurred over as short as timescale as a decade or so.

The observations lend credence to earlier, disputed, reports that finds of microscopic grains of diamond and a mineral called lonsdaleite in lake sediments dated to the same time were identified with a possible meteorite impact.
Those measurements resemble the most recent observations of remnants of the Tunguska meteorite impact in Siberia, reported last month.

Sphere-shaped particles have also been identified at many localities in sediments dating to this event, most recently reported this month by a team led from Canada in the Journal of Geology. Such particles are characteristic of the rapidly heated and cooled splatter of material thrown up when meteorites hit Earth.

While the platinum data and the spherical particles add to evidence for an impact event, doubters have pointed out that, as yet, no impact site has been identified.

It has been suggested that debris thrown into the atmosphere in an impact tipped the Earth into global cooling at a rate as rapid as the global changes in climate in the reverse direction seen in the last century.

Such rapid climate change makes it difficult for ecologies and societies to adjust: It is the fluctuation that has been invoked as the cause of the extinction of massive mammals (megafauna) like the mammoth, and native cultures such as the Clovis people in North America.

The possible role of cosmic impacts in causing huge changes to life on Earth is receiving increased attention. The mass extinction 66 million years ago that wiped out the dinosaurs is generally believed to be linked to a space strike in southern Mexico's Yucatan Peninsula.
Recently, a group of scientists led by Eric Tohver at the University of Western Australia reported that the biggest extinction of all, which occurred 252.3 million years ago at the end of the Permian period, could be explained by an asteroid impact in Brazil.

Nasa is now focusing resources towards detection of future Earth-threatening asteroids, receiving over 400 responses to their recent request for ideas to feed into their Asteroid Grand Challenge, in which they hope to redirect a space rock and send humans to study it.

http://www.bbc.co.uk/news/science-environment-23536567

Posted: 06-08-2013 13:01 Post subject:

The best is yet to come?