There’s been a lot of buzz about space lately. NASA’s hunt for extraterrestrial life on Mars is well underway thanks to Perseverance (nicknamed Percy), the rover roaming about Jezero Crater. This hypothesized ancient river delta is all dried up but could have once teemed with life. Then there’s Ingenuity–the helicopter that hitched a ride to Mars by holding on to the underbelly of Percy before partaking in increasingly adventurous test flights. Over in the private sector, Elon Musk’s SpaceX has been revolutionising the space game. Space tourism has become a bit of a hot topic thanks to Jeff Bezos and Richard Branson’s suborbital space flights. The upward trend in the commercialisation of space is hardly unexpected, though it remains a bitter pill to swallow for some. A naïve perspective perhaps, but space has always held a certain mythical charm, a charm which is chipped away by the likes of stargazers who see the vast expanse of the sky as the perfect billboard for advertisements (I kid you not). Yet, feelings aside, there’s a more pressing concern with space commercialisation: the accumulation of space junk.
The colonisation of space has always been humanity’s dream. As we draw closer to realising it with the help of the renewed vigour put forth by these moguls, it doesn’t seem to represent everyone’s interest as it once did. A greater number of people are questioning its need when our planet is run-down after centuries of being battered down and probably requires our undivided attention. And perhaps, in some sense of cruel irony, our increasing dabbles in space have led to concerns about the accumulation of space debris, a problem which will only get worse with time, mirroring our own fight with pollution back here on Earth. A cynic might say this is humanity’s trademark–to wreak havoc everywhere man sets his gaze (it’s me, I’m the cynic). Yet, this article is not a cynic’s vent–it is merely an overview on space junk, so here goes.
A Look into the Figures
Space debris is just that–it’s junk humans left behind in space. And boy, there’s a ton of it. The United States’ Department of Defense makes use of its Space Surveillance Network sensors to track space junk–over 27,000 pieces. And they look out for this junk in the Earth’s orbit, tracking objects as small as 5 cm in diameter in the Low Earth Orbit (LEO) and 1 m in the Geosynchronous Orbit (GEO). But what about objects smaller than that? While the sensors can’t detect them, they are significantly more abundant. It appears that the abundance of debris is inversely proportional to its size. According to NASA, there are roughly 23,000 pieces of debris sized at 10 cm or more, 0.5 million pieces at 1 cm or more, and a whopping 100 million pieces at 1 mm or more, and so forth. The damage inflicted by these orbital objects are a result of the high speed at which they travel. It’s fast enough that space debris is a cause for concern regardless of their size, though, of course, the larger the debris, the more dangerous the outcome–it is estimated that debris larger than 10 cm can shatter a satellite or spacecraft in space.
The Origin Story
So, where does the junk come from? The most common type of space junk are the satellites. The benefits of satellites are irrefutable, but it’s safe to say that it’s getting a little crowded up there. According to the ESA, less than a third of satellites in space are operational. The rest? They’re just dead weight–roughly 6300 tonnes of dead weight. And a single collision in orbit can result in collisions all the way down. Moreover, when these satellites re-enter the Earth’s atmosphere, they can potentially endanger human lives. The only human to have experienced such an event thus far is Lottie Williams who was struck in the arm by a 15 cm long piece of space junk whose origins can be traced to a U.S. Ballistic Missile Defense Organization’s Delta II rocket which launched in 1996, one year before the incident took place.
Of course, it’s not just satellites. It is literally everything humans left behind in space–lost astronaut gear, paint flecks, metal fragments, pieces of rockets and spacecraft, and many explosion remnants.
A Brief, Incomplete Account of Collisions
According to NASA, two prominent events contributed to a 70% increase in trackable orbital debris – an incident in 2007 where China used anti-satellite technology to destroy their weather spacecraft “Fengyun-1C,” and created over 3500 pieces of large debris, and the accidental collision of the US’ Iridium satellite and Russia’s Kosmos satellite in 2009, which contributed an additional 2300 pieces.
There’s even been a couple of incidents regarding paint flecks! In 2016, space debris, which was at most a few thousandths of a mm big, chipped a window of the International Space Station. Moreover, NASA has had to replace space shuttle windows that were damaged by paint flecks!
So, what is being done about it?
Tracking space debris remains the most important tool in our arsenal. For the larger 10 cm sized space junk, the ISS can carry out conjunction assessments (CA) and collision/debris avoidance manoeuvres. However, suppose, for whatever reason, a manoeuvre isn’t a feasible course of action. In that case, the ISS crew can then make their way into the crew spacecraft that shuttle them to and from the ISS, and close the hatches, protecting them from damages such as loss of pressure. These manoeuvres typically occur when there’s at least a 1 in 100,000 chance of collision, and they take 5 hours to prepare for; to date, the ISS has carried out a total of 29 debris avoidance manoeuvres. Additionally, shields are in place to withstand particles sized smaller than 1 cm. A similar system is in place for spacecraft and satellites.
While avoiding debris is one way to navigate the issue, two other factors play an equally important role: mitigation and remediation. What can we do to avoid adding to the orbital debris, and what can we do to remove existing debris actively? Well, the answer to the first question is complicated. With private companies wanting a piece of the space pie, there’s been an explosion in the number of satellites being launched into space. Take SpaceX’s Starlink: it hopes to provide the world with low latency internet with the help of satellites and has launched 60 of them to date. However, the company has mitigated the space junk issue by ensuring that they re-enter Earth’s atmosphere instead of hanging around in orbit once they’re no longer in use. While space junk falling towards the Earth sounds pretty alarming, as we’ve established, the odds of it inflicting damage to human life is currently very low, and most of it burns up while re-entering the Earth’s atmosphere. Hopefully, other companies implement similar approaches, though the more crowded it gets, the more likely it is that collisions occur.
Remediation is a tricky one to tackle. Even if we were to completely mitigate the issue or even stop all our launches (hypothetically), the constant collisions that would continue to occur would still increase the amount of space debris floating around. One proposed solution is to make use of harpoons and nets to either pull debris into the grasp of Earth’s atmosphere or push debris into a higher so-called “graveyard” orbit where it will do much less harm. Another solution is to make use of trusty lasers to function as a broom. Then there’s the more expensive solution: satellites. Perhaps, clean up solutions are best suited for private ventures, where innovation is most likely to happen and is already underway.
Space debris has been a problem long before private entities entered the space game. But, with the rise in our space ventures and the increase in awareness about the issues with space debris, everyone involved in the space game must put in an effort to mitigate the problem, remedy the situation, and prevent any further collisions.