What's the risk from asteroids, and what's being done about it?
Provided By - Video Elephant on June 21, 2018
Asteroids pose a risk to our planet, and you only need to visit a museum to see the proof. Sixty six million years ago thing we going just fine for the dinosaurs, until one day, a large and fast-moving space rock crossed paths with the Earth.
"The asteroid was just ten kilometres, but the resulting crater was 200 kilometres," explains Christian Köberl, one of Europe's leading asteroid experts, director of the Natural History Museum Vienna , and Professor at the University of Vienna .
"So that tells us about the enormous energy that's involved in such a case. And that energy is like a gigantic explosion, earthquakes happened, all kinds of nasty things, so the climate changed immediately. And what that meant is that a lot of the animals and plants at that time, almost two thirds became extinct, about two thirds of all living species on our planet became extinct," he says.
The killer blow came from mountain-sized lump of silicate rock, iron and nickel left over from the formation of the solar system. It's the threat from these kinds of civilisation-ending asteroids, and their city-smashing smaller brethren that the international community is now trying to find ways to mitigate.
Asteroids strike Tunguska and Chelyabinsk
Large asteroid strikes are very, very rare. However, there are many reminders of the damage a smaller asteroid can do in recent history. International Asteroid Day itself is placed on 30th June every year to mark the anniversary of the Tunguska Event , when an asteroid exploded over Siberia and flattened 2,000 square kilometres of forest. In 2013, an asteroid just 20 metres across, exploded above the Russian city of Chelyabinsk , injuring 1,500 people, mostly from broken glass.
Studying asteroids - or meteorites as they are known once they hit the ground - can reveal a great deal
At the Museum in Vienna we met up with Ludovic Ferrière, Meteorite Curator, who showed us a piece of the Chelyabinsk asteroid.
"When we cut it open we can see the history of this meteorite," he says.
"You can see the original part, which hasn't been much changed since its formation, and which will tell us about the solar system. And all the black part, that's from a series of impacts that it has had between its formation 4.56 billion years ago and today."
Its history of impacts deep in its past meant the Chelyabinsk asteroid exploded in the atmosphere, rather than hitting the ground and causing a great deal more damage.
The NHM in Vienna is home to the world's largest display of meteorites, and shows just how varied they can be in terms of structure, with some being almost solid iron, while others are a loose amalgam of silicates.
Exactly where they land is also a factor in how much damage they cause. A house-sized space rock can destroy a forest, create a tsunami, or even alter our atmosphere, as asteroid researcher at the University of Vienna, Lidia Pitarello, explains: "In the case of a shallow sea, and it depends on the type of sediments that we have on the bottom, then a lot of greenhouse gases can be released, by the vaporisation of the material, and then it can really affect the climate on the long term."
What's being done to protect our planet from asteroids?
At ESA in Darmstadt, Germany , the Space Safety team is working on developing an early warning system, particularly for the more numerous, smaller asteroids. A two metre space rock was filmed by farmers Barend Swanepoel and Vicus van Zyl over South Africa in early June, exploding in a bright flash in the sky.
"That’s what we want to observe, because if it’s a bit bigger, maybe 5 metres, then the shockwave can create a significant damage on the surface, and that’s what we want to inform the people about, beforehand," says Rüdiger Jehn, Near Earth Object Segment Leader at ESA.
Rüdiger currently pilots a telescope in the hills west of Madrid to spot unknown asteroids, but will soon be using ESA's new Flyeye telescope, to be installed in Sicilly, and specifically developed for the task of observing near Earth objects.
The Agency is already monitoring 740 asteroids that carry a small risk of hitting Earth, and finds new ones all the time.
"We currently have a detection rate of something like 200 asteroids per month, and maybe 3, 4 or 5 of them are objects which might hit the Earth," says Jehn.
"There’s none which is really a serious threat, which we currently know of. There’s plenty of things out there which we have not yet detected, which we are still searching for, but from what we know right now there’s nothing which we really have to worry about."
Mascot to land on an asteroid
It's good to know your enemy, and there is lots of activity in the space sector to boost our knowledge of asteroids.
ESA is developing the Hera/AIM mission to follow NASA's AIDA asteroid redirect mission in the coming decade, while both NASA and Japanese space agency JAXA