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Indian-origin space scientist says India needs to focus on meteor defense

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Bengaluru: An Indian-origin space scientist said that India needs to focus on reconnaissance infrastructure, putting in place a meteor defence and develop a national meteor disaster preparedness policy after the last week Tamil Nadu incident in which a man was killed inside college campus by meteorite strike.

“Catastrophies originating from outer space are no fiction,” Chaitanya Giri, who was earlier with Max Planck Institute for Solar System Research in Germany and is currently with the Earth Life Science Institute in Tokyo, told this correspondent in an email.

Such catastrophies “are potential and credible threats to our national interests,” he said.

Giri said the US, in 2005, mandated its NASA space agency to build infrastructure for surveillance of potentially hazardous asteroids and to divert those on a likely collision course with Earth. The European Union, Japan, and Russia followed suit and are continually tracking comets and asteroids while Canada has its own “near earth object surveillance satellite” to identify unwelcome visitors from space, he said.

“Space capable India has not joined this club,” Giri said.

In fact, the seven-foot wide satellite junk that fell off the southern coast of Sri Lanka on November 13, 2015, was identified by a US ground-based sky survey infrastructure while its fall trajectory was projected by the the European Sky network, Giri said.

“While these nations have built up the networks to ward of dangers from space, India is totally unprepared to counter the impact of destructive meter-scale meteorites and extinction-level kilometre-scale asteroids or comets,” he said.

Giri said India’s prehistory is dotted with meteors of different sizes such as Lonar in Maharashtra (two km wide) and Ramgarh in Rajasthan (four km wide), adding an 11-km-wide meteorite that hit Dhala in Madhya Pradesh “could have unleashed energy many times higher than the largest atomic detonation”.

While it is true such kilometres-wide meteorites fall once in several thousand years, smaller metre-scale meteorites fall frequently and unleash limited regional destruction, he said.

Giri pointed out that a 20-year (1994-2013) global map released by NASA in 2014 shows numerous metre-scale meteors exploding all over the Indian Ocean region and the Indian sub-continent with energy approximately equivalent to the atomic bomb dropped over Nagasaki in 1945. Also, the Geological Survey of India (GSI) in the past 15 years has reported numerous meteoritic falls mostly centimetre-scale chunks from all over India.

In February 2013, a meteor, 20 metres in diameter, exploded 30 km above the city of Chelyabinsk in Russia with an energy approximately 25 times more powerful than the Nagasaki bomb, causing thousands of human injuries and damage worth billions of dollars. Bangkok experienced meteorite falls twice in September 2015. Nearer home, on February 27, 2015, a meteor exploded over Kozhikode, Malappuram, Palakkad and Thrissur in Kerala to finally impact at several locations in Ernakulam district. All these events demonstrate that the threat from meteors is real, Giri said.

With its massive geographical land mass and vast exclusive economic zone, India has all the legitimate reasons to develop a planetary defence programme of its own and create an operational national preparedness policy for various meteor disaster scenarios, he said.

“To this effect, New Delhi should exploit ISRO’s capabilities for constructing an indigenous ground- and space-based reconnaissance network that would track potentially hazardous objects as small as one metre,” he said. Had such a system been in place, there would have been no room for controversy over the cause of explosion heard in Vellore last week.

“The verdict whether it was due to meteorite or not should be supported by peer-reviewed evidence,” Giri said, dismissing news reports quoting scientists of the Indian Institute of Astrophysics (IIAP) in Bengaluru that the sample it examined did not look like meteorite.

“The Geological Survey of India is the authority on meteorite curation and not IIAP whose faculty are mainly astronomers,” Giri said. Further, the IIAP scientists did not collect the samples themselves but tested the sample given by the police “which is not the most appropriate thing to do,” he said.

“I also do not know if they looked for the presence of iridium, an element that you do not get on Earth and is predominantly extra-terrestrial in origin. Hence I do not consider IIAP’s sampling and verdict at face value.”

Giri said a video uploaded on the internet shows the trail of a meteor over Chennai with its trajectory towards the West (the direction to Vellore). If this video is true, the Vellore event is most likely due to meteorite, he said. (IANS)(image: mashable.com)

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Asteroids Are Falling On Earth’s Surface Twice As Often: Study

This enhanced impact rate poses a threat for the next mass extinction event.

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Asteroids
This Dec. 29, 1968, photo made available by NASA shows craters on the moon. For the past 290 million years, giant rocks from space have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study. VOA

Giant rocks from space are falling from the sky more than they used to, but don’t worry.

For the past 290 million years, large asteroids have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study in Thursday’s journal Science.

But no need to cast a wary glance up. Asteroids still only smack Earth on average every million or few million years, even with the increased crash rate. NASA’s list of potential big space rock crashes shows no pending major threats. The biggest known risk is a 4,200-foot (1.3-km) wide asteroid with a 99.988 percent chance that it will miss Earth when it whizzes very near here in 861 years.

Tell that to the dinosaurs. Most scientists think dinosaurs and a lot of other species went extinct after a huge space rock crashed into Central America about 65 million years ago.

Earth, Asteroids
Taurids meteor shower lights up the sky. The risk of asteroids hitting the Earth has grown over the years. Wikimedia

“It’s just a game of probabilities,” said study lead author Sara Mazrouei, a University of Toronto planetary scientist. “These events are still rare and far between that I’m not too worried about it.”

Mazrouei and colleagues in the United Kingdom and United States compiled a list of impact craters on Earth and the moon that were larger than 12 miles (20 km) wide and came up with the dates of them. It takes a space rock that’s half a mile (800 meters) wide to create holes that big.

The team counted 29 craters that were no older than 290 million years and nine between 291 million years and 650 million years old.

But we can see relatively few big craters on Earth because the planet is more than 70 percent ocean and past glaciers smoothed out some holes, said University of Toronto planetary scientist Rebecca Ghent, a study co-author.

Earth, Asteroids
These rocks were rare survivors from a very different time on Earth. Pixabay

Extrapolating for what can’t be seen brings the total to about 260 space crashes on Earth in the last 290 million years. Adding in other factors, the science team determined that the current space crash rate is 2.6 times more than the previous 700 million years.

Craters older than 650 million years are mostly wiped off on Earth by glacial forces so the scientists used impact craters on the nearby moon as a stand-in for holes between 650 million and 1 billion years old. The moon is a good guide for estimating Earth crashes, because it is close enough to be in the same bombardment path and its craters last longer.

Mixed reactions

So what happened nearly 300 million years ago?

“Perhaps an asteroid family was broken up in the asteroid belt,” Mazrouei speculated. The space rocks then headed toward the Earth and moon, and the planet got slightly more because it is a bigger target and it has higher gravity, Ghent said.

Oldest known asteroid family
An asteroid family. Wikimedia

Outside scientists are split about the research. Jay Melosh at Purdue said he found the number of craters too small to come to a reasonable conclusion, but Harvard’s Avi Loeb said the case was convincing.

Also Read: Newly Discovered Super-Earth Exoplanet May Sustain Primitive Life

Humans might not have emerged without mass extinctions from space rocks about 250 million and 65 million years ago, Loeb said in an email, adding, “but this enhanced impact rate poses a threat for the next mass extinction event, which we should watch for and attempt to avoid with the aid of technology.”

“This demonstrates how arbitrary and fragile human life is,” Loeb wrote. (VOA)