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Members of NASA, federal agencies, and international partners are busy this week pretending an asteroid will impact Earth by 2027. Although the impact is completely fictional, the exercise allows scientists and civil servants to understand what actions may be necessary should a space rock end up on a collision course with our planet.
On the first day of the conference, the team pretended they had just discovered asteroid 2019 PDC, an object between 100 and 300 meters (330 to 980 feet) in size that will fly by Earth on May 13, 2019, passing at 19 million kilometers (12 million miles). The object will stop being observable by Earth-based telescopes by the end of the year and will not get close to our planet until 2027. At this point, it will have a one in 100 chance of hitting Earth.
The team wanted to provide a fake but realistic scenario. If this fake asteroid were a reality, it could create devastation on a continental scale. Given the uncertainty about the object, it could land on April 29, 2027, in a narrow band that extends from Hawaii to Africa, crossing the continental United States.
On the second day, the members jumped forward in time to July 29, 2019. Now, scientists have observed the object and noted there is a one in 10 chance of the object slamming into Earth. They have also refined the asteroid's size estimates to roughly 140 to 260 meters (460 to 850 feet) and determined it is a pile-of-rubble kind of object. They also believe they know where it might hit: Denver, Colorado.
If the object were to hit with no warning (remember this is just a simulation), over 2 million people would be in the unsurvivable zone. The energy released would be tens of thousands of times the energy released by an atomic bomb, igniting buildings and making sand explode over 1,300 square kilometers (500 square miles).
So what can we do? First up is a reconnaissance mission to understand more about the object, especially its mass. The mission would launch on June 1, 2021, and arrive on December 30 of the same year. During this time, agencies would also build two more reconnaissance missions, one with the ability to deploy a nuclear device to potentially deflect the object and a second as a nuclear deflector mission.
The third day starts on December 30, 2021. Things have changed since 2019. The nuclear device mission has been deemed too controversial both nationally and internationally. Instead, a single reconnaissance mission will launch in a few months time (spring 2022), with a previously launched planetary spacecraft sent to follow 2019 PDC. Six “kinetic impactors” built by NASA, the European Space Agency, Russia, and China will be launched in mid-2023.
At this point, the density of the asteroid is still not known, so scientists are uncertain how successful the deflection mission will be. For it to succeed, they will have to generate a change in velocity for an eastward deflection of 4.5 centimeters per second, thus displacing it by about 12,100 kilometers (7,520 miles) and putting it off course. The impactors are scheduled to take place on the last week of August 2024, with one of the spacecraft remaining in orbit to determine if they are successful.
Day 4 and 5 will tell us what happens next.
