Wednesday, March 13, 2013

Are we safe?

 

Pilot David Randal is tasked to fly top-secret photographs from a South African astronomer named Dr Emery  Bronson to Dr Cole Hendron in the United States. On reception, Dr Hendron realises that Dr Bronson has discovered the unthinkable; another heavenly body — a star named Bellus — is on a collision course with Earth.

From the picture, Dr Hendron’s scientific mind calculates that the end of the world is only eight months away and he begins a one-man “save humanity” crusade.

He contacts the United Nations and the United States government to relay this information and express his fears, hoping that they can sponsor the construction of evacuation spaceships to ferry people to another planet, only to be turned down and get sniggered at by fellow scientists.

As the star gets closer, earthquakes, volcanic eruptions, and tidal waves destroy buildings and kill people. A wheelchair-bound industrialist, Sidney Stanton, funds Dr Hendron’s group and a ship is built, then loaded with food, medicine, equipment, animals, and books. But there is the little problem of choosing those who will be lucky to get on board. They turn to choosing through a lottery.

Anxiety, desperation, suspicion, fear, and violence are the prevailing emotions. Losers of the lottery riot, trying to force their way aboard the ship. Eventually, the vessel sails off and Bellus — the star — collides with the earth, wiping out those left behind.

Reads like a movie, does it not? Well, it is a movie, and what you have just read is the synopsis of the 1951 film, When Worlds Collide, directed by Rudolph Mate and winner of that year’s Academy Award for special effects.

But February 19, 2013 was no movie. And there were no Academy Awards nor special effects. A meteorite that NASA estimates  to have been between 15.2 and 16.8 metres wide and weighing  about 10,000 tonnes flew into the earth’s atmosphere over Russia’s Chelyabinsk region before exploding.

The effect; a shock wave that shattered walls and windows across three major cities in the region, damaged a zinc plant, and left close to 1,200 people injured. Large holes were also found on the surfaces of frozen ice lakes. The damage was valued at $33 million (Sh2.8 billion). No one saw the thing coming. At least in the movie, the South African scientist saw Bellus coming and gave the world an eight-month heads-up for preparation.

As the public and scientists reeled from the effects and shock of the Russian meteorite fall, another asteroid, 45.7 metres wide, flew past the earth at a height of only 27 kilometres, the closest ever for a mass of that size.

NASA says the Russian meteorite was slightly larger than a bus. Luckily, the space agency says, the earth’s atmosphere absorbed a vast majority of its energy, but it still exploded with the force of several atomic bombs.

A force of several atomic bombs and they still say “lucky”? The reasons are twofold; the meteorite was travelling at a speed of 10 miles per hour, a relatively low speed for such objects, and it broke into smaller pieces between 18 and 32 miles above the ground, according to the Russian Academy of Sciences.

One Mr Igor Chudnovsky, a resident of Chelyabinsk, did not feel so lucky.

“I woke up to a blast. It felt like the whole building had jumped up. I saw light and it looked like it was from a nuclear explosion, like I had seen in documentaries,” he said in an interview with NASA.

Another retiree from central Russia, Tamara Khabarova, fearing that they may get struck again, said: “I am very afraid. But what can we do? It is God’s hands.”

Scientists believe that the space rock was the largest to have entered the atmosphere since 1908 and that it was unusual as well for the scale of its effects: more than 1,200 people injured and broad property damage.

Indeed, the event is providing a first indication of the type of structural and infrastructural costs meteors can exact from a highly industrialised society. NASA scientists say a meteor of this size strikes the earth about once every hundred years.

Shattered glass caused most of the damage and injuries in Chelyabinsk, a sprawling industrial city of about one million people. What shattered the glass, scientists say, was both the explosion as the meteor fragmented and the waves of pressure created as it decelerated.

Such low-frequency waves — called infrasound — are sometimes detected by Cold War-era nuclear blast sensors in remote parts of the Pacific Ocean or Alaska, according to meteor experts. The waves can bounce off buildings and be stronger in some places than others; they can also resonate with glass, explaining why bottles and dishes might have shattered inside undamaged kitchens, as if crushed by the airy hand of the meteor itself.

So what exactly are we to be afraid of? What are the heavenly bodies that occasionally zoom past the earth and, in some instances, land on it? How frequently do they land on the earth? What could their impact be? Most importantly, are we safe from these near-earth objects?

Could it be that the fate of humanity is like that of the dinosaurs, whose extinction, scientists say, was speeded up by a 15-kilometre-wide asteroid that smashed into the earth at Chicxulub, Mexico, clearing out 75 per cent of the earth’s living species?

Known to scientists as the Cretaceous-Paleogene extinction, this even led to the mutations and diversification of species that eventually saw the rise of Homo Sapiens.

Every year, 20,000 meteorites land on the earth, mostly (and luckily) in areas where there is little human population. But that is changing and increasingly there are risks of these rock bodies landing in a densely populated area like an urban centre. The fact that most of them are always just a few centimetres wide or just a few kilogrammes heavy is no consolation, at least after what happened in Russia recently.

A 10-kilometre-wide asteroid or meteorite would have an almost similar effect to that which sent dinosaurs into extinction.

Near-earth objects are categorised depending on their sizes. Those between zero and 100 feet wide are many and not too dangerous. In fact, in some parts of the world, people stand out during the night to watch some of these bodies as they burn up in the air, never reaching the ground.

If they fail to burn up completely, as has been witnessed in parts of Europe, Africa, South America, and Oceania, they are known to lead to considerable panic, destruction, and loss of property.

In 1924, a meteorite sent mourners scampering for safety in Colorado. Five years later at a wedding party in Yugoslavia, another meteorite struck, sending guests home without enjoying the booze. Talk of a bad wedding crasher.

However, it is only Anne Elizabeth who knew (she has since passed on) what it is to be hit by a meteorite after a four-kilogramme rock mass smashed through her roof and struck her in the hip in 1954. She died later of kidney failure, aged 52. In Africa, Egypt and Sudan (in 2008) have experienced significant meteorite crashes.

On June 30, 1908, a close to 150-feet-wide rock mass entered the earth’s  atmosphere, split into several pieces way up in the skies, but one piece, which was reported to be as tall as 12-storey building, zoomed down at a speed of one kilometre per second and landed in Tunguska River, Siberia.

The forest around the river lost 2,000 square kilometres of trees (about 80 million trees), and the entire area was flattened in a blast that rose 10 kilometres above the ground and released about 12 megatonnes of energy, the equivalent of several Hiroshima bombs.

Scientist shudder to think of what would have happened had the meteor landed whole.

Whereas the real chances of these bodies colliding with the earth are slim, the events of February reminded scientists just how unsafe the earth is from other bodies that share with it the universe.

Most developed countries have their own centres for studying near-earth objects. Through these studies, they hope to accomplish two things: to optimise their preparation for these crashes, and to predict the exact time of their landings so that, if need be, they can evacuate people.

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