Asteroids are cool… but far from our biggest problem up in space

Several weeks ago, there were a flurry of headlines about the chances of a newly discovered asteroid – 2024 YR4 – hitting Earth. The highest probability stated was 3.1%, about a 1 in 32 chance of hitting. Since this peak, the odds of a collision have been downgraded to a 0.0004% chance – so essentially zero. This drop in likelihood is understandable: when asteroids (or any object for that matter) are first identified, tracking models have a limited amount of data they can use to chart a course. As more observations are made, more data is collected, and these models are refined. Such was the case with 2024 YR4.

With initial estimates having placed the asteroid at a ‘keep-an-eye-on-it’ level, some media outlets very helpfully speculated that a cataclysm was inbound, whilst others attempted to calm matters by noting that the asteroid was only big enough to wipe out a city, so we could all rest easy. However, having watched the discussion unfold, this coverage – arguably – overplayed the issue, as even at the highest estimation, there was still a 97% chance of it missing Earth, which are rather nice odds. Added to this, there was no information as to where it may land in the event of a collision. As most of the Earth’s surface is water, it would probably be safe for us to relax (in most instances).

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Although asteroids make for splashy headlines due to the Armageddon-type scenes we’ve all watched in Hollywood movies and the fact they wiped out the dinosaurs, the likelihood of them creating a humanity-ending event is very unlikely. So, a big deal was made over a 3.1% chance.

While it’s understandable that this event grabbed headlines, this relatively unlikely outcome distracts from a much larger issue that poses more risk but doesn’t generate the same level of public interest: space debris. As human activity in space increases, so does the amount of debris – or ‘junk’ – left floating around in space. This has implications for both activities in orbit and for us living on Earth, with increasing instances of ‘uncontrolled re-entries’ (crash landings) happening. Some instances have already grabbed headlines, with the rocket stage from China’s Long March 5B having fallen back to Earth in 2022 and, more recently, a SpaceX Falcon 9 rocket crashing into Poland.

Although instances such as these are fairly rare, with increasing numbers of satellites, launches, and payloads (the equipment or instruments being carried), the likelihood of such events increases. Space junk is not simply an issue for those of us wandering around on the Earth’s surface, either: it also poses increasing risks to objects in Earth’s orbit. While a collision in Outer Space may not seem like something worth worrying about on Earth, the satellites in space enable us to forecast the weather, monitor and respond to natural disasters, use GPS, and helps to monitor sea and air traffic. So, pretty handy stuff!

We don’t have to start looking skywards for small pieces of junk hitting us here on the ground – smaller pieces tend to burn up on re-entry, so we don’t even notice it. However, small pieces of junk can be a problem for those lovely satellites that help us do all sorts of things – including many of the GPS-enabled services on our smartphones that we’ve come to rely upon.

A particularly big concern for people like me who study Outer Space is that a lot of space junk is too small to track: the European Space Agency currently tracks about 40,230 objects in space (covering those of most concern or most notable). However, its estimates indicate that there are approximately 131,140,500 pieces of junk 1mm or larger. These may be small but are a bit of a pain when travelling at high speed in orbit. Added to this issue of tracking small pieces of junk is that not all items launched into space are registered: current UN figures estimate that 88% of stuff launched into space has been registered, meaning there’s a fair bit we aren’t too sure about. Tracking this is also becoming harder with the increasing involvement of the likes of SpaceX in the private sector, which is increasing launch frequencies.

Given the present and growing scale of space junk, there is a pressing need for us to consider how we ensure that different space agencies (whether state- or private-led) comply with the requirement to register the objects they launch and – perhaps most importantly – to take responsibility for their equipment. Whilst there is some international law relating to the issue of responsibility and accountability, there is a question about how able we are to enforce this. For example, in the 1980s, Russia was famously required to pay Canada recompense for crashing into them. However, less than 25% of this fine has been paid to date…

So, while asteroids are splashy and eye catching, we should spare some more thought for the closer and more pressing matter of space junk. We need to track, regulate, and prevent space junk as this stuff is much closer – and far more likely – to come crashing down around us or into space-based equipment that we rely on in our everyday lives.

Dr Craig Henry Jones is a lecturer in management and society at Lancaster University Management School.

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