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Last week, NASA and several federal agencies, together with multiple international organizations, planned an exercise that might in the future save millions of lives. They simulated what would happen if an asteroid was discovered on a collision course with Earth. It didn't end well.
The exercise, part of the Planetary Defense Conference, allows researchers to work out scientific, technical, and political challenges that will have to be overcome in order to successfully protect our planet from an asteroid impact.
The simulation, which condenses eight fictional years into five days, went like this: Thanks to ground-based observations, it's discovered the fictional asteroid 2019 PDC has a 1 in 100 chance of hitting Earth. On Day 2 it's calculated that risk is now 1 in 10 and will likely hit Denver, Colorado on April 29, 2027. The planning phases of both the reconnaissance and deflecting missions step up a gear. By Day 3, set in late December 2021, the first reconnaissance spacecraft has reached the asteroid. On the deflection mission, several spacecraft are due to slam into the asteroid in August 2024, to push it off orbit.
Day 4 started a few days after the deflection – and brought some good news and some very bad news. The main body of the asteroid was successfully deflected but a small fragment 50-80 meters (165-260 feet) in size was still on a collision course with Earth – New York City to be precise. On top of that, the debris released by the impact destroyed the reconnaissance spacecraft making it much harder to know what was happening.
"We need to challenge ourselves and ask the tough questions. You don't learn anything if you don't study the worst possible case each day," explained Paul Chodas, director of the Center for Near Earth Object Studies at NASA's JPL, and creator of this year's scenario, in a statement.
Having run out of options, the team re-proposed the nuclear option that was discussed on Day 2 but was shelved due to widespread controversy and risk. They looked at sending a 300-kiloton nuclear device to explode less than 145 meters (476 feet) from the asteroid fragment, which would either deflect it or fragment it, calculations showed.
But even with confidence in the numbers – the same strategy managed to save Tokyo in last year's simulation – the mission could not be implemented due to political disagreements, and the asteroid could not be stopped. All there was left to do was prepare New York City for impact.
Day 5 began just 10 days before impact. The asteroid would enter the atmosphere at 19 kilometers per second (43,000 mph) and release the equivalent of 5-20 megatons of energy in the airburst. It would explode about 15 kilometers (9 miles) above Central Park, destroying the city, and creating a 15-kilometer (9-mile) "unsurvivable" radius.
In this scenario, it's the Federal Emergency Management Agency's (FEMA) job to evacuate and rehome 10 million people, their pets and belongings, protect nuclear and chemical installations in the area, and transfer works of art. The tone of the conversation shifted from the technical and scientific, to the sociological, legal, and political, and all the questions that come with that. How are people going to behave? Who’s paying for it all? What about insurance (the deflection caused it to hit New York, not Denver, after all)?
"This exercise is valuable in that it continues the work currently in progress to identify key questions and issues for this low probability but high consequence scenario," said FEMA's Leviticus Lewis.
We managed to save Tokyo in last year's exercise, but other fictional victims of asteroids include the French Riviera, Dhaka, and Los Angeles. However, the likelihood of an asteroid impacting Earth remains highly unlikely and the exercises are devised to be the worst case within the realm of possibilities. But like good scouts, it's good to be prepared. The next exercise will take place in Vienna in 2021. Hopefully, the next target city might escape this grim fate.
