We're getting better than ever at monitoring these incoming space rocks, but we still only get a few days or weeks notice when something is about to shoot past our planet. Luckily, up until now, nothing we've spotted has been on a collision course with Earth. But what happens if they are?
Finally, the White House has released a detailed plan, titled "National Near-Earth Object Preparedness Strategy", to prepare for just such an event.
The document was developed by the Interagency Working Group for Detecting and Mitigating the Impact of Earth-bound Near-Earth Objects (DAMIEN), and published last month by the White House Office of Science and Technology Policy.
According to the document, the aim is to "improve our nation's preparedness to address the hazard of near-Earth object (NEO) impacts by enhancing the integration of existing national and international assets and adding important capabilities that are currently lacking".
When you consider the fact that we had no warning before the 17-metre meteor that struck Chelyabinsk in 2013, injuring more than 1,000 people - or that we only just spotted a 1-km-wide object zooming towards Earth a few weeks ago - it becomes apparent how unprepared we really are for one of these events.
When we're talking about NEOs, we're referring to asteroids or comets that have an orbit that brings them near or into Earth's orbit.
These can be just a few metres in size or up to several kilometres wide, like the one that is thought to have wiped out the dinosaurs.
The Planetary Society estimates that we've discovered only around 60 percent of the NEOs estimated to be larger than 1.5-km-wide out there, even though they're finding about five new asteroids of all types every night.
The graph below, taken from the White House document, shows the current known near-Earth asteroids (green bars), the current estimate of how many are out there (red line) and how much more we have to survey (blue line).
Those red words along the top show how bad the damage would be from each category.
The new strategy builds on work NASA is already doing to better detect and study NEOs, but takes things to the next level to ensure the objects are spotted early enough, as well as providing some insight into what we need to do if we do identify an asteroid on a collision course with our planet.
The strategy has been broken down into seven main goals in the new document, which we'll share below and break down into plain English.
1. Enhance NEO detection, tracking, and characterisation capabilities
2. Develop methods for NEO deflection and disruption
These objectives include developing capabilities for fast response, as well as figuring out how to either deflect or disrupt the path of incoming asteroids. Think Bruce Willis drilling nukes into the side of the Armageddon asteroid.
3. Improve modelling, predictions, and information integration
The objective of this goal is to figure out how to better model the trajectories of NEO and reduce uncertainty. The ultimate goal is to know for sure whether or not something is going to hit us, and how bad it's going to be.
4. Develop emergency procedures for NEO impact scenarios
This is an important one - putting procedures in place for exactly what goes down and how after we detect a NEO on a collision course.
5. Establish NEO impact response and recovery procedures
Okay, this is a last resort. But assuming an impact is unavoidable, what do we do next? This will depend on whether the NEO will strike in the deep ocean, on a coastal region, in a city, or in the middle of nowhere. Setting up protocols for every possible scenario will be the key to recovery after the event (let's hope that's an option).
6. Leverage and support international cooperation
When it comes to working together as a planet, there's nothing like an incoming asteroid to make you realise how insignificant borders really are. This step of the strategy deals with how the US and NASA will work with foreign governments to plan, monitor, and prepare for NEO events.
7. Establish coordination and communications protocols and thresholds for taking action
This one's all about communication and setting up protocols for who gets told about NEO events first, and when and how this gets communicated to the media and the public. These protocols will also help the US decide whether or not they should attempt to deflect or deter the asteroid, or whether we prepare for impact. They'll also outline what happens when the projected impact falls outside US territory.
Obviously one strategy document isn't going to be enough to save us from an incoming NEO. The real problem is that we're still not detecting asteroids early enough, and we don't have enough options of how to deal with them when we do spot them.
But the fact that the White House has finally mapped all the steps that need to be taken so we can get a little closer to a state of readiness is a big deal. And it's comforting for those of us painfully aware of the fact that we're just a big rock in a Solar System full of debris.
The good news is, 'potentially hazardous asteroids' have less than a 0.01 percent chance of impacting Earth in the next 100 years. So we don't need to worry too soon. But there's nothing wrong with being prepared.
You can read the full statement here.