“Currently, there is no known asteroid with a significant probability of impacting Earth in the next century.” This reassuring news comes to us via NASA’s Jet Propulsion Lab (JPL), which last week conducted an exercise about a fictional asteroid on a collision course with the Earth. It didn’t go well for us.
In conjuction with the 2019 International Academy of Astronautics (IAA) Interplanetary Defense Conference in Washington, DC, NASA, the International Asteroid Warning Network (IAWN), and their colleagues worked over 5 days to prevent a near-Earth asteroid from hitting the planet. Details of the fictional 8-year scenario are available at the JPL web site.
On Day 1 of the exercise (occurring now), a press release announced that “a recently discovered near-Earth asteroid could pass very close to the Earth 8 years from now, on April 29, 2027, and there is a small chance—1 in 100—that it could impact our planet.” By Day 2, 2 months from now, those odds had decreased to 1 in 10, and NASA calculated that if the 850-foot asteroid hit the Earth, “it could release in the range of 100 to 800 megatons of equivalent energy…”
Day 3, set in late December 2021, saw NASA definitively identifying Denver, Colorado as the site of impact on April 29, 2027. With the European, Japanese, Chinese, and Russian space agencies, NASA immediately made plans to build and deploy six “kinetic impactor spacecraft” within the following 2 years. You can probably guess what the goal was: “hitting the asteroid with a spacecraft to incrementally slow the speed of the asteroid to deflect it off its impact course with Earth.” Yes, the Armageddon/Deep Impact maneuver strikes again.
And just like in those movies, smashing the asteroid didn’t erase the threat. A large fragment was still heading toward the Eastern seaboard of the U.S. as of Day 4 (August 2024). On Day 5, April 19, 2027, the final prediction was that the asteroid would explode 9 miles above Central Park in New York City (not at the Statue of Liberty?) just after midnight only 10 days later.
“The small asteroid will enter Earth’s atmosphere at 19 km/s (43,000 mph) on April 29, producing a very large fireball or “megabolide,” and predicted to release the equivalent of 5 to 20 megatons of energy in the airburst.”
For comparison, the yield of the larger atomic bomb released during World War II was “only” 22 kilotons. In the NASA scenario, within 2 minutes, structural damage and heat sufficient to produce second-degree burns would be expected to radiate up to 275 miles from the epicenter, an area encompassing 10 million people. Ten days is nowhere near enough time to get everybody out. We either need better long-range scanning, better kinetic impactor spacecraft, or both.
Vienna will be the next target, in 2021. Let’s hope they have better luck.
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