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On 15 February 2013, a meteoroid survived its descent into the Earth’s atmosphere over Ural Russia, where it broke the sound barrier and exploded near the city of Chelyabinsk. This created a shockwave that blew out thousands of windows, cracked buildings, injured more than 1200 people and showered the area in meteorite fragments.

The largest remaining fragment of Russia’s meteorite is thought to have plunged into Lake Chebarkul, leaving a hole 6 m in diameter in the surface ice. NASA estimates that the size of the meteoroid prior to entering Earth’s atmosphere was 17 m in diameter, with an estimated mass of 10,000 tons (9 071 847.4 kg).

Wealth of visual records

As a sign of the times, the Chelyabinsk meteor’s fiery mid-morning arrival was undoubtedly the most closely recorded in history, with numerous Russian drivers’ dash-cams and other videos capturing the event. The footage was uploaded within minutes. The recordings give scientists a wealth of visual records to analyse in order to understand the object’s point of entry into the atmosphere, its flight path and eventual demise.

So far, more than 100 meteorite fragments have been recovered by or handed over to the Russian Academy of Sciences from a 50 km stretch along the object’s flight path. The largest fragment weighs about a kilogram. In what can only be described as a ‘meteorite rush’, many fragments have turned up on eBay and other auction sites, although authorities have warned would-be meteorite owners that many are likely to be fakes. As yet, no meteorite has been recovered from the lake bed, where it is likely to be buried beneath metres of lake silt.

Common chondrite

The academy reports that the stony meteorite fragments are 4.5 billion-year-old common chondrite – the most common make-up of asteroids. Despite its name, common or ordinary chondrite consists of minerals such as olivine, pyroxene, troilite and kamacite in combinations that aren’t found on Earth.

Scientists believe the meteoroid probably broke off an asteroid when it collided with another space body millions of years ago, before beginning its eventual collision course with Earth.

Russia is no stranger to meteors. In 1908, scientists say a meteoroid, named Tunguska, exploded in the air above Siberia, flattening 2000 square km of uninhabited forest.

Tonnes of space material hit Earth every day

In an interview with the UK Science Media Centre, Dr Simon Goodwin, Reader in Astrophysics from the University of Sheffield’s Department of Physics and Astronomy, said in regards to Russia’s meteoroid that objects from space are hitting us all the time. “Estimates are that 1000 to 10,000 tonnes of material from space rain down onto the Earth every day. The vast majority are small [can be measured in mm or cm] and burn up high in the atmosphere. These ‘shooting stars’ look pretty and cause no damage at all. How far something gets through the atmosphere depends on how big it is and what it’s made of. Metal or solid rock [meteoroids] can often get to the ground.

“It seems like the damage from the meteor in Russia was not due to the meteorite hitting the ground. It seems to have been caused by a shock wave as either the [meteoroid] broke the sound barrier or maybe exploded in the air. This shock wave then broke windows and caused the damage and injury.

“While events this big are rare, an impact that could cause damage and death could happen every century or so. It very much depends on where it hits – the Tunguska impact killed nobody, but if it had hit a few hours later, it could have killed a million by exploding over St Petersburg.

“A big enough meteor could cause significant immediate death and maybe cause climate change by releasing dust into the air – these are maybe every few thousand years. An impact into the sea could cause a worldwide tsunami, causing lots of damage in any low-lying area, and a really big impact occurs every few tens of millions of years and can cause mass extinctions,” says Dr Goodwin.

Chance of an impact causing deaths

Dr Goodwin says that, while the impact happened at about the same time that the asteroid 2012 DA14 was passing fairly close to Earth, the two events are probably not related. He says the importance of the Chelyabinsk event is to make people realise that things fall from space all the time. “Every now and then they can be dangerous – maybe very dangerous. Unfortunately, there is absolutely nothing we can do to stop impacts. So far, there are no confirmed reports that anyone has ever died due directly to an impact, but it will happen eventually. An impact in a heavily populated area could kill huge numbers of people with no warning or chance of stopping it.”

A meteorite impact in Mexico, leaving a crater 200 km in diameter, is widely credited with wiping out the dinosaurs around 65 million years ago.

The cost of damage to Chelyabinsk city is estimated in excess of 1 billion roubles (about NZ$40 million).

Useful link

More information about the Chelyabinsk meteorite in NASA’s asteroid and comet watch news.
www.nasa.gov/mission_pages/asteroids/news/asteroid20130215.html

Activity idea

Have a look at this timeline with your students. They can find out when the Mexico meteorite strike occurred and what ecological impact this had.

Our changing ecosystems – timeline

    Published 30 April 2013 Referencing Hub articles