‘Not if, but when’: NASA simulates a huge asteroid hitting a major city

It’s a chilling prospect: a huge rock hurtling towards the Earth from space, with only a few days to prepare for impact.

But NASA describes the scenario of a smaller asteroid striking Earth as ‘not if – but when.’

NASA recently simulated what would happen if a 300 to 800ft asteroid approached Los Angeles with an 100% chance of impact.

‘It’s not a matter of if – but when – we will deal with such a situation,’ said Thomas Zurbuchen, Associate Administrator for NASA’s Science Mission Directorate in Washington.

‘But unlike any other time in our history, we now have the ability to respond to an impact threat through continued observations, predictions, response planning and mitigation.’

The simulation took place in El Segundo, Califonia on October 25 – and looked at how emergency planners would respond to the scenario.

Emergency planners investigated a scenario where telescopes tracked an object with an impact probability of 65% – but then couldn’t observe the asteroid for four months, due to its position relative to the sun.

When it reappears, it has an impact probability of 100% – leading to a rapid evacuation of Los Angeles.

‘The high degree of initial uncertainty coupled with the relatively long impact warning time made this scenario unique and especially challenging for emergency managers,’ said FEMA National Response Coordination Branch Chief Leviticus A. Lewis.

‘It’s quite different from preparing for an event with a much shorter timeline, such as a hurricane.’