This year has witnessed heightened space exploration and related activities, headlined by the American and Chinese government-led Mars rover missions as well as commercial launches by SpaceX, Virgin Galactic and Blue Origin. Among these landmark milestones were less laudable moments that generated concern, most notably criticism regarding the uncontrolled reentry of a Chinese Long March 5B rocket in early May, generating fresh debate among nations and non-governmental organizations about the issue of space debris. While no damage was caused on the ground, a previous Long March 5B rained debris over West Africa.
Re-entering objects by type without human spaceflight. ESA chart.
Outer space, like our oceans, is free from conventional political boundaries and thus requires internationally agreed upon laws. While some policies have been set in place, beginning with the Outer Space Treaty of 1967, others like those regarding our spatial footprint haven’t. As space launches advance at unprecedented rates and per-kilogram launch costs continue to fall, particularly to reach low Earth orbit (LEO), more missions mean more debris. What does this mean for the future of space exploration?
Space debris is defined by NASA as any human-made object in orbit around the Earth that no longer serves a function. As space use for everything from communication and exploration to meteorology and climate research becomes more ubiquitous, debris proliferates accordingly. During the past 64 years of space activity, more than 6,050 launches have resulted in about 56,450 tracked objects in space, according to the European Space Agency (ESA). More than 28,000 of these remain in orbit, mostly in LEO, which NASA has deemed a “space orbital junkyard.” Causes of increased debris are often traced to fragmentation events, which can include satellite and rocket explosions, antisatellite tests and collisions. Douglas Loverro, resident of Loverro Consulting, broke space debris into three categories. The first is the small class; smaller pieces that eventually wear down into even smaller particles and are never catastrophic. The second are larger items that reenter the atmosphere and fall to Earth (concerning, but odds are low of human impact). The last are medium to large items that never reenter the atmosphere, but that collide with other items to create more debris and interfere with current space activity. It’s this last group, Loverro said, that we should be most worried about.
The space debris crisis stands at a turning point. Space debris isn’t like marine debris, Loverro pointed out. There is no bottom of the ocean for junk to sink to — whatever is there now will be there in the future. That said, the situation in space, while not quite catastrophic, has reached a place where “long-term and high rates of environmental remediation, i.e., actively removing space debris from orbit, is the only way forward to ensure the sustainable use of outer space,” explained Stijn Lemmens, senior space debris mitigation analyst at the ESA. The increasing risk of collisions has become such the “norm” for operators during the past decade that designers of new missions are often asked to assess the risk that an impact with an unavoidable piece of debris could have. “The challenge now,” Lemmens said, “is to change our ways now and to treat space a shared resource so we can adopt sustainable practices and ensure that the crisis, which could effectively mean that certain orbital regions can’t be used anymore due to too high levels of space debris, does not unfold decades from now because of inaction today.”
Low Earth orbit (LEO) is the region of space within 2,000 km of the Earth’s surface. It is the most concentrated area for orbital debris. NASA ODPO image.
Responsibilities
The problem has been made clear. But what should be done? And whose responsibility is it to clean outer space? Under the current set of international space laws, each country is liable for the debris that results from their activity and the companies under their jurisdiction. A collaboration between government and industry is ideal for tackling the problem, Lemmens emphasized: “For example, companies can share their operational best practices (like collision avoidance coordination) and be a driver for the implementation of new technologies (like propulsion systems to get satellites out of orbit after the mission).” Countries, on the other hand, have the power to set policy on the minimum requirements to be allowed in space, setting design and operation standards for sustainable practices. In order to hold companies and countries accountable, though, we need some sort of international governing body, like the Chicago Convention on International Civil Aviation in 1944 that set the rules of international air travel into place.
Professor Danielle Wood, Director of Space Enabled at the MIT Media Lab, flies on a reduced gravity plane flight with Dr. Ariel Ekblaw, Director of the Media Lab’s Space Exploration Initiative. During the research flight, Space Enabled tested a system to manufacture wax as a non-toxic fuel for satellites in microgravity, part of a research portfolio to develop space technology that is sustainable and accessible. Steve Boxall/Zero-G Corp. image.
Morally, however, the question of responsibility has a more nuanced answer. Space sustainability is also a matter of justice, argued Danielle Wood, MIT assistant professor and director of the Space Enabled research group. “The mission of the Space Enabled research group,” Wood said, “is to advance justice in Earth’s complex systems using designs enabled by space.” There are six types of space technology supporting societal needs, as defined by the United Nations Sustainable Development Goals. This includes satellite operations, like earth observation, communication, and positioning, as well as microgravity research, technology transfer, and the inspiration derived from space exploration, through both research and education. These technologies, as well as societal development, are all impacted by increasing quantities of space debris. “Space sustainability means, for earth orbit, maintaining a healthy and reasonable number of objects in space and operating in a safe way.” However, it goes beyond that as humans are going to impact places like the Moon, asteroids and even Mars in the future, Wood argued. Nations also have a moral obligation to consider how they’ve already impacted the space environment, holding themselves accountable for the debris that’s already up there. “We should also have a moral responsibility to maintain the pristine geologic and cultural value of places in space for the future,” Wood pointed out, citing the role that celestial spaces play in many indigenous cultures. This means, by and large, that space sustainability must be achievable through more than just environmentally sound practices and healthy political and economic relationships — social equity and moral accountability are crucial, too.
Assessment of the sustainability of a space mission at various stages of its lifecycle is shown above. Images courtesy of the Space Sustainability Rating Consortium (ESA, Space Enabled Research Group within the MIT Media Lab, in cooperation with the University of Texas at Austin, BryceTech and the Forum).
Topical modules, part of the Space Sustainability Rating, are being developed to assess overall sustainability is based on rating systems like LEED (Leadership in Energy and Environmental Design) certification for buildings.
To facilitate space launch accountability, the Space Sustainability Rating (SSR) is being developed, with the intention to start serving customers by 2022. “The SSR aims to adopt the current minimum set of practices to avoid a space debris crisis and put in the spotlight those operators that go well beyond this level. It is thus meant to be an inherently positive message an applicant can give to its stakeholders and customer if they pass the rating process,” Lemmens explained. The SSR is hosted by the École Polytechnique Fédérale de Lausanne (EPFL) Space Center (also known as eSpace), and its design team comprises of the World Economic Forum, the ESA, Wood’s Space Enabled research team, the University of Texas at Austin, and BryceTech. The concept is based on successful rating systems in other industries like the LEED (Leadership in Energy and Environmental Design) certification for buildings. The rating process itself begins during the design phase, Lemmens explained, when an applicant fills out a questionnaire to assess sustainable practices associated with the design and concept of the mission’s operations. At this point, a preliminary rating is issued, to be confirmed after launch. As defined in a recent press release from the World Economic Forum, the scores will be based on factors including data sharing, choice of orbit, measures to avoid collisions, and plans to de-orbit satellites. The choice and characteristics of a launch provider could even impact the score, with optional elements, like de-orbiting fixtures, adding bonus points.
ClearSpace-1 Mission: Operational concept of chaser satellite that is able to rendezvous, inspect and capture debris. ClearSpace image.
Aside from encouraging sustainable methods, the SSR process has another large goal: “It is the intention that this will be a public process, as one of the objectives of the rating is to create transparency,” Lemmens said. Additionally, operators and manufacturers will be able to share their level of certification (out of a total of four), further increasing transparency in a sensitive way while incentivizing positive action by all players in the space debris crisis.
Removal
While legal and moral responsibility in the space debris crisis is important, and policy holds a powerful role, the market for technology and an increase in activity to remove debris are also necessary. ClearSpace, a spin-off of EPFL, is already working on this challenge. The company, based in Switzerland, aims to provide affordable in-orbit services to remove non-operational satellites and prevent the future buildup of debris, said co-founders CEO Luc Piguet and chief engineer Muriel Richard. In November 2020, ClearSpace signed a contract with the ESA to launch ClearSpace-1 in 2025, a mission designed to remove VESPA, a part of a European rocket launched in 2013. The mission is the first within the ESA project ADRIOS, Active Debris Removal/In Orbit Servicing. “ClearSpace will lead the development of a chaser satellite that is able to rendezvous, inspect and capture debris which has not been prepared or designed for removal by using a capture mechanism (four robotic arms) and a set of sensors,” Piguet and Richard explained. “Once the object is secured, the chaser will then place the object into a re-entry orbit into earth atmosphere where it will burn up like a shooting star.” As part of this project, ClearSpace is leading a commercial consortium to build the capture mechanism; the consortium includes eight countries (Switzerland, Germany, Romania, the United Kingdom, Sweden, Poland, the Czech Republic, and Portugal) and companies like Airbus and OHB Sweden. The company has three objectives to achieve through the ClearSpace-1 mission: “to set up an infrastructure to deliver service, to test technologies, and finally, to bring and demonstrate the feasibility of a breakdown service,” said the co-founders. They added, “Our objective is to reduce the costs of in-orbit servicing and active debris removal. We believe that this is a critical step toward sustainable space operations.”
Toby Harris, Head of Space Situational Awareness at Astroscale UK. Astroscale UK & Europe image.
ClearSpace is not alone in waging the technological battle against space debris. Astroscale, an in-orbit debris removal company based in Japan, has a vision to secure the safe and sustainable development of space for future generations, explained Toby Harris, head of Space Situation Awareness (SSA) at Astroscale UK. “SSA,” Harris said, “is all about building a complete picture of what is happening in space understanding where both spacecraft and space debris are, what they are doing and what they are going to do.” The field is also important for ensuring space safety by making sure spacecraft don’t collide with others or get hit by a rogue piece of debris. Harris’ role is also responsible for considering how Astroscale can contribute to SSA capabilities, like using onboard sensors to provide additional observations and tracking. Astroscale’s in-orbit services include active debris removal (ADR) missions to eliminate existing defunct options like old rocket bodies, upper stages and failed spacecraft. “By removing these larger objects from orbit, the risk of their fragmentation, either from an explosion or collision, is removed, and so are the consequences of such a break-up, including the many small, very high velocity fragments that can destroy other spacecraft,” he added. Astroscale is also looking into end-of-life (EOL) services to make debris removal easier in the future, lessening the risk of creating more debris objects that would threaten future space sustainability. More specifically, the ELSA-d mission was launched in March of this year to test a magnetic docking system on a dummy defunct satellite and to inform the success of EOL missions that utilize prepared commercial spacecraft with a docking plate. “The various sensor payloads onboard the spacecraft will also be examined and tested to understand how different instruments perform and how they might be improved upon in the future,” said Harris. “We’re also considering how sensor payloads could be used in a flexible manner for navigation, understanding how a client spacecraft is moving when nearby, and performing broader on-orbit space surveillance and tracking of potential debris spacecraft.”
Risk
While the space debris problem may be increasing in size, beginning discussions and technology development at this stage allows for proactive change in how missions operate into the future. The problem, though, is unavoidable even if all launches were to stop immediately, Lemmens said. “This is simply due to the amount of space debris already in orbit that will collide among itself and create more, but smaller, debris pieces on orbit.”
This means that in any future scenario, implementing measures to avoid collisions and designing systems to track and remove debris will be important. And, as our space activity is only ramping up as more companies and governments get involved, these actions hold even greater power. Policy implementation will need to take initiative as well, Wood explained, working to remediate the waste stream of past actions, establish just treatment of humans and the environment, and consider the existence of a multi-location society as we explore further with both good governance and equity. While the SSR is a positive step forward, “it’s just the beginning,” she said. “It can’t be the final policy. We’re going to need a multi-faceted approach in the future.”
In terms of technology, the impacts of collisions due to too much debris can already be seen, destroying satellites valuable to Earth for things like global communication or meteorological services. “As space situational awareness systems become better at seeing smaller and more objects, and as satellite systems grow larger, such as Starlink or OneWeb, reducing human unpredictability and congestion in orbits will be essential,” Harris said. “ADR and EOL missions will benefit from improved autonomy together with new developments in robotic capture mechanisms, such as docking plate and robotic arm technology.”
“Another risk,” the ClearSpace co-founders shared, “is that if more collisions occur, entire fields of space may not be usable again, and that would be a legacy we would leave for generations to come.” To combat the debris crises, Piguet and Richard broke the solution into three parts: “The first is making sure that all satellites dispose of self-deorbiting capabilities and are deorbited at the end of their life. Next, is the implementation of transparent information sharing between space stakeholders to allow for effective space traffic management and collision avoidance for live satellites, and lastly, a towing service to remove the failure rates from orbit.”
Simply put, the space debris crisis is one of astronomical size on an astronomical scale. While the severity of potential collisions increases with each new launch, so do the opportunities and motivation to instill positive change before the problem exceeds our capacity to address it. Our activity in space supports that on Earth — as it fills up with debris, becomes more crowded, and the likelihood of collisions increase, technologies that are crucial to the functioning of society (national defense, PNT, weather services, communication, etc.) are put at risk.
Unlike the marine debris crisis, which didn’t see an increase in momentum to clean the oceans until recently, it is early enough to establish common habits to prevent irreversible issues in the space industry down the road. The balance between policy, obligation, and technology is an important one, with each branch playing a role to contain the growing orbital junkyard. As SpaceX and Blue Origin have shown us, space exploration, business, and technological advancement is far from halting and only becoming slowly more accessible to society. If we are to maintain this pace, our pledge to sustainability must keep up, preserving the space environment for generations to come.
See related column on page 64.
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