9 minute read
The growing problem of orbital debris and space congestion
We depend on satellites for our global wellbeing. Without them, civilization as we know it would quickly disintegrate, leaving us in chaos and uncertainty. Space debris and congestion are posing a double threat to orbital safety, and we need to address it now.
Joe Chan, Director of Flight Dynamics at Intelsat
Imagine a world where satellites are no longer operational. Essential services would quickly fail, and global society would begin to crumble. Communication systems would collapse as mobile networks and the internet fail. Power grids, unable to coordinate distribution, would suffer frequent blackouts, plunging cities into darkness. Aviation and maritime navigation would become untenable, causing trade to grind to a halt. This would then lead to widespread shortages of food and other essential supplies. Financial systems would break down, triggering economic chaos and rampant inflation. Civil unrest would erupt, and governments would struggle to maintain order.
As societies regressed to more rudimentary technologies and solutions, communities would need to adapt quickly to survive in a fragmented, disconnected world.
While this vision of the future could be deemed sensationalist, it at least conveys the point that if we don’t address the growing problem of orbital debris and increased space traffic, we’re heading towards a bleak future. If left unchecked, these issues pose significant risks to operational satellites and other space missions. ESA’s Annual Space Environment Report illustrates how if we continue to act in the same way as we currently are, some orbits will become unusable due to the high density of space debris. For continued and future use of space, satellites must be able to operate safely and avoid collisions. However, as the number of objects in space increases, this will become more and more difficult.
From Sputnik I To Now
There have been a growing number of headlines around space debris in the mainstream media of late, which perhaps indicates a growing interest and awareness around orbital debris and space safety in general. This year, we’ve had headlines about the infamous toolbox dropped by a NASA astronaut during a space walk around the International Space Station (ISS), as well as the case of the debris object that hit a house in Florida which has since been identified as the remains of a pallet of batteries jettisoned from the ISS three years ago.
As we know, orbital debris is not a new phenomenon. It has been accumulating since the first satellite, Sputnik I, was launched in 1957. Now, some 67 years, 6,500 rocket launches, and 16,900 satellites later, ESA estimates that there are over one million pieces of space debris in orbit measuring over 1cm. Add in even smaller pieces and you’re looking at a number somewhere over the 131 million mark. ESA has also calculated that even if no new missions were launched from now on, the number of debris objects would continue to increase because larger pieces would still break up at a typical rate of four to five per year.
These days, it’s not unusual for operators to perform on average two collision avoidance manoeuvres per year for every satellite in operation. ESA reports that it performs three to four of these manoeuvres per year with each of its Earth orbiting spacecraft. These manoeuvres are costly for operators in terms of time spent assessing the risk, fuel used to move away from the object, as well as downtime because of the avoidance manoeuvre. As orbital debris increases, there will undoubtedly be calls for more of these manoeuvres which will have significant cost implications for operators.
Cost implications aside, if left unaddressed, the accumulation of space debris could lead to a cascade effect known as the Kessler Syndrome, where collisions between objects in space create more debris, leading to further collisions and an exponential increase in debris. This scenario could render certain orbits unusable, severely limiting space activity. At best this means higher costs and risks associated with operating satellites, increased insurance premiums, and potential disruptions to services. The worst-case scenario is the dystopian future described at the beginning of this piece.
Reducing Risks
To protect the future use of space, we need to reduce the risks associated with debris and prevent collisions. This is a complex challenge. At its most basic level, we need to stop creating new debris, improve Space Situational Awareness (SSA) systems and develop ways to actively remove existing debris.
1 - Prevent new debris from being added by adopting responsible satellite life cycle management
Although the number of debris will increase even without further launches, it’s critical that we prevent the creation of new debris from being added to orbit. To do this, the entire industry needs to manage satellite life cycles more responsibly, including implementing adopted best practices, and improving deorbiting strategies. Ensuring that satellites are designed with end-of-life disposal plans, such as controlled re-entry or moving to a graveyard orbit, is crucial.
This approach significantly reduces the potential for future debris generation. Recognizing this, the US FCC moved from a 25-year orbiting rule to five years for all FCC licensed LEO satellites. Similarly, ESA LEO missions have also moved from 25 to five years.
A recent NASA report on the cost and benefit analysis of mitigating, tracking, and remediating orbital debris highlighted that rapidly deorbiting defunct spacecraft is one of the best measures for managing orbital debris. The analysis found that changing from a 25-year rule to a loweryear rule is a cost-effective way to reduce risk to space operators. It also concluded that more net benefits could be gained by reducing the deorbit timeline further than five years; moving all the way to a 0-year rule could result in nearly US$9 billion in net benefits. This is certainly something to aspire to.
2 - Enhance Space Situational Awareness
Improving SSA is essential for tracking and monitoring space debris so that we know the location of debris as well as where it will be soon. When this information is accurate, it’s possible to predict potential collisions so that operators can decide how to respond. Tracking and monitoring all the debris that can cause harm is a huge undertaking for obvious reasons. The number of debris pieces is in the millions, some pieces are very small and difficult to see, pieces are moving at high speeds, and their orbit paths can be difficult to predict.
Technology in this field is advancing all the time. Developments are making it possible to assess potential collisions (conjunctions) with more accuracy, as well as locate and monitor smaller pieces of debris than was feasible in the past. Modern SSA systems may employ ground-based and space-based sensors to detect and track objects in space, alongside pooling data from various sources.
There are several different public and private SSA systems in operation, and the accuracy of conjunction assessments varies enormously. The Space Data Centre (SDC), run by not-for-profit member organization Space Data Association (SDA), is one such platform that provides conjunction assessment and warning services. Supported by COMSPOC, the SDC ingests flight dynamics information from the member companies as well as other available sources of space object information. It utilises member provided ephemerides, with integrated manoeuvre information and fuses this with TLE (Two Line Elements) and SP (Special Perturbation) data from the public catalogue to accurately assess the possibility of a conjunction.
3 - Remediate existing debris
In addition to preventing the creation of new debris and improving SSA, debris remediation is required to reduce the risks of existing debris. This could mean moving debris to prevent a collision, removing it completely from orbit, or possibly even reusing and recycling it. A number of technologies are being developed in order to move debris out of the pathway of spacecrafts. For example, research currently being carried out by West Virginia University and funded by NASA is exploring whether the process of laser ablation and photon pressure performed by a network of space-based lasers, is a viable option to remove debris of varying sizes. This approach targets the debris with a laser beam, or multiple laser beams, to vaporise a small part of it, in order to generate a high-velocity plasma plume that changes the trajectory of the debris. Another method that is attracting a lot of interest is the deployment of micron scale dust to enhance the drag of debris, to move it to a different path, or to force re-entry.
The market for space debris removal solutions and services is rapidly expanding and there are a number of commercial companies working to develop ways to actively remove debris. Japanese company Ex-Fusion is developing a ground-based fusion laser system that uses powerful lasers developed for nuclear fusion power, but at an order of magnitude lower, to remove or redirect debris. The company reportedly aims to test the technology at the EOS Space Systems observatory near Canberra in Australia.
Swiss company ClearSpace has developed a capture system that uses robotic arms to target and capture debris for safe removal. ESA has commissioned the company to target and remove a defunct 112kg Vespa upper stage rocket part from orbit, under the ClearSpace-1 mission.
ClearSpace is also leading the Clearing the LEO Environment with Active Removal (CLEAR) mission, which is funded by the UK Space Agency, and aims to remove two UK satellites from orbit that are both roughly the size of a washing machine. Japanese company Astroscale is another private company working in the field of debris removal. It has developed and successfully trialed a magnetic capture system (the ELSA-d mission) for retrieving defunct satellites or other objects, for removal and for on-orbit servicing. The company is also undertaking another mission, ADRAS-J, commissioned by the Japanese government, to safely approach and characterise an existing piece of large debris, a prelude to capturing and removing debris.
Momentum Is Building
Managing and mitigating the risks associated with both space debris and increased space traffic is an incredibly complex challenge and we don’t yet have all the answers. It does however feel like the momentum is building, and we’re starting to make some headway. Public-private partnerships like those highlighted above are clearly going to be critical in developing effective debris mitigation and removal technologies.
A number of sustainability initiatives and guidelines for mitigating the impact of debris have also recently been introduced by organisations and agencies such as ESA, NASA, and the UK Space Agency.
These are a welcome step in the right direction, as are the growing number of collaborative and industry led initiatives being launched to improve space safety and protect the future use of space. Now that we’ve started to make some progress, it’s critical that we keep this momentum going.
