The last few years have been difficult, with many disasters, including the pandemic that is still affecting us. Because of this, it has become popular to ‘predict’ the next disaster, with many online saying that a killer asteroid is the only thing that is missing now. While this is of course said in jest, it is not a bad question overall. What are the risks of us getting hit by an ‘Armageddon’ style killer asteroid that wipes us all out?
What’re the chances of Earth being struck by a mega asteroid?
Fortunately, the odds are extremely low. Asteroids that are 1000 km (600 miles) across do not exist in our solar system, apart from the dwarf planet Ceres. Ceres is also in a stable orbit, which means that there is a virtually 0% chance of us getting hit by the asteroid belt object.
There are, of course, many much smaller asteroids flying around, and an impact from them could still cause major problems, albeit more localized. Fortunately, we have the combined efforts of thousands of astronomers, amateur observers, and dedicated asteroid search robots to help us map the skies and search for potential threats. These are mapped, tracked, and assessed by the ESA near-earth objects coordination centre, who have a public list of thousands of asteroids and their orbits available. Currently, there are over 1200 asteroids in the ‘risk list’, which means that they have a ‘non-zero’ impact probability and need to be monitored. These probabilities can be as low as one in 5 or one in several million, and happily, it’s the small ones that have the highest risk usually.
ESA’s Planteray Defense office
Besides the object coordination centre, ESA also has a Planetary Defense office which is focused on the safety and security of the world when it comes to asteroid threats. On their website we find that they have five main goals.
- Become aware of current and future near-earth objects relative to our planet.
- Estimate the likelihood of a collision with Earth.
- Assess the consequences of such an impact.
- Inform relevant parties. E.g. local governments and response agencies.
- Develop methods to deflect asteroids and prevent collisions.
The Defence office works closely with the coordination center and other space agencies to develop new methods of deflecting asteroids. Typically these are not nuclear missiles, although they might get used in dire situations. A more favored approach is that of a gravity tractor, which is basically a heavy satellite that would orbit the asteroid and slowly change its orbit over the course of months or even years. This of course means that we need to know well in advance that the asteroid is headed our way, which is why the agency also has specialized telescopes and goes through data of astronomers.
Keeping a close eye on the sky
All in all, there is not much to worry about. We have an accurate map of all asteroids that could pose a threat and are developing more and more tools to deal with them if they come too close. One potential problem though is the new Star link project and similar super constellations, which fill the night sky with bright lights that make surveys of the sky hard to near-impossible. The full ramifications of these projects have not yet been assessed, but some astronomers are worried about it. Let’s hope that a solution can be found.