Asteroid impacts are incredibly rare events, but they have the potential to cause irreparable damage to our planet. This year at the Planetary Defense Conference, a group of people took part in efforts to prepare the world for a fictional impact. Hosted by the International Academy of Astronautics, the 7th conference took place in Vienna at the end of April. The simulated scenario played out over a few days and was designed to show our level of preparedness in the face of such a disaster. For while the threat from asteroids is a constant one, with enough warning we could prevent an impact.
Unlike other natural disasters, it’s thought that we could completely prevent an asteroid impact given sufficient warning. Instead of simply mitigating the effects, the asteroid could be deflected or destroyed. Telescopes all across the world are engaged in surveys, searching the skies for dangerous objects in space. Because of this, scientists are pretty certain that we have discovered all of the larger asteroids in our solar system, but the smaller they are, the harder they are to detect. Since they travel round the Sun as we do, it is possible to predict their path. Therefore, if any collision is ahead, we can know in advance. But what would happen if we found them too late?
The following scenario is FICTITIOUS.
Our simulated asteroid was discovered by the PAN-STARRS near-Earth object survey project on the 19th April 2021. It was quickly surmised that it would impact the Earth in less than six months. What followed is an example of the procedures in place in the case of a real asteroid. The International Asteroid Warning Network (IAWN) published weekly updates for the public, whilst the Space Missions Planning Advisory Group (SMPAG) began considering the options available to prevent the disaster. Examples include a high-energy impact, ‘gravity tractor’ or ‘ion beam shepherd’, but all rely on a small deflection of the asteroid. If this happens early enough, the asteroid’s new trajectory will lead it past the Earth.
3 days in to the conference (2 months of simulated time), SMPAG conclude that preventing an impact is impossible. All the options would require building and launching spacecraft, which could not be done in the 4 months before the impact. Asteroid 2021 PDC crashes into Europe, completely destroying a 100km wide area.
Although fictional, the scenario described here is more than plausible. The reality is that without sufficient warning, there is almost nothing we can do to prevent an impact like this. However, awareness is rising, and there are sky survey such as PAN-STARRS that are searching the skies daily for new Near Earth Objects (NEOs). The chances of any of these posing a threat to our planet are incredibly remote, but if we continue watching we just might get the warning we need.