'These events are not rare': NASA exercise highlights existential threat of asteroid impacting Earth

Catastrophic asteroid impacts have long been fodder for Hollywood, such as in 1997's Deep Impact. Photo / Supplied

It's the doomsday scenario fit for a Hollywood blockbuster — and NASA scientists are about to see it go down.

This week researchers will run an exercise at the 2019 Planetary Defence Conference that will play out a "realistic scenario" of an asteroid flying through space on an impact trajectory with Earth, reports news.com.au

NASA's Planetary Defence Co-ordination Office (PDCO) is running the simulation exercise as part of a recently announced federal "action plan" for defending our planet against asteroid impact.

The hypothetical asteroid is thought to be about 100 to 300 metres in size and only has a very small likelihood of smashing into Earth on April 29, 2027, according to a NASA web page dedicated to the highly detailed scenario.

Global astronomers are always on the lookout for near-Earth objects (NEOs), which are classified as asteroids and comets that orbit the Sun and come within 50 million kilometres of Earth's orbit.

Along with the NASA unit, the European Space Agency's Space Situational Awareness-NEO Segment and the International Asteroid Warning Network (IAWN) are tasked with hunting the skies for potentially dangerous space rocks.

These "tabletop exercises" are not uncommon and are about walking through the steps that will need to be taken along with governments and emergency agencies to mitigate the risk to society should the unthinkable happen.

"These exercises have really helped us in the planetary defence community to understand what our colleagues on the disaster management side need to know," said Lindley Johnson, NASA's planetary defence officer. "This exercise will help us develop more effective communications with each other and with our governments."

NASA has been tasked with the goal of identifying and tracking 90 per cent of near-Earth meteors that are larger than 140 metres by the year 2020. But the task could end up taking nearly three decades, experts claim. And even then we're far from protected.

Last month, it was revealed a relatively small and undetected meteor blew up over the Bering Sea, off Russia's Kamchatka Peninsula on December 18. The explosion — which happened 25.6 kilometres above the Earth's surface — released 10 times the energy produced by the atomic bomb dropped on Hiroshima in World War II.

Six years ago, a meteor exploded over the Russian city of Chelyabinsk and released a shockwave that shattered thousands of windows and injured more than 1600 people. That meteor was only 19 metres wide.

A meteor streaks through the sky over Chelyabinsk, Russia, in 2013. Photo / AP

"The thing is the one over Chelyabinsk and this latest one (in December) are about 10 times smaller" that the ones targeted by the NASA mandate, astronomer Alan Duffy explained to news.com.au last month. "It's far harder to detect those, and we still haven't found all the larger asteroids yet."

He has called for more funding to be allocated to monitoring systems, asserting "it is just a matter of time before one of these blasts occur over a city and cause incredible damage".

During a keynote address at the opening of the Planetary Defence Conference, NASA administrator Jim Bridenstine warned preparing for an asteroid impact is something that needs to be taken very seriously.

"We have to make sure that people understand that this is not about Hollywood, it's not about movies. This is about ultimately protecting the only planet we know, right now, to host life, and that is the planet Earth," he said.
"These events are not rare, they happen."