As we dangerously head towards a debris-congested space environment, it is imperative that we ramp up our space traffic management before it becomes too late.
With more than 60 years of history in spacefaring and 6050 launch missions, we have left behind at least 27,000 fragments of space debris in our planet’s orbits, which are tracked by the U.S. government. This number only accounts for larger pieces of junk that are sizeable enough to be tracked. Adding to this, there exists about 500,000 chunks of debris larger than 1 centimeter and 100 million more tinier bits around 1 millimeter in size.
As if the numbers aren’t concerning enough, the projectile speed (about 15,700 mph in low Earth orbit) at which these space junks are hurtling can be hazardous to operational space infrastructure in their way. Even a pea-sized speck of space debris colliding with a satellite or space vehicle can result in disastrous consequences. In essence, the entire space sector, worth hundreds of billions of dollars, is at risk.
Due to the severe impact of collisions, the threat posed by space debris is taken into serious regard by NASA. Thus, the space administration has an established set of guidelines that is meant to be followed when the space station is in imminent danger of colliding with a piece of space debris.
In one of the most recent instances, Russia deorbitted one of its Soviet-era satellites by obliterating it with a missile. This resulted in orbital litter of more than 1,500 chunks of space debris, large enough to be trackable. More alarming was the fact that the cloud of debris was right in the way of the International Space Station and astronauts on board had to scramble to their spacecraft for safety while the station had to adjust its orbit to avoid impact.
Truth is these chunks of debris did not appear out of thin air. Unfortunately, it is our irresponsible behaviour that has led to the creation of the hazardous orbital environment. In the enthusiasm to carry out the latest space operations to research the final frontier, we have forgotten to be mindful of the space environment. Most of the orbital debris today consists of parts of manmade objects, such as spacecrafts, defunct satellites, rocket stages, and tiny bits and pieces of scrap resulting from an explosion in space, including flecks of paint.
Besides accidents leading to explosions resulting in more space litter, such as the collision of an American communication satellite with a Russian military satellite in February 2009 that generated more than 2,300 trackable fragments, there have been purposeful orbital explosions as well. Over the past couple of years, anti-satellite tests that involve sending missiles to shoot down deorbited satellites have come into popularity. China’s FengYun-1C engagement that occurred in January 2007 alone has escalated the trackable space object population by 25%!
When it comes down to resolving the issue, it is not the responsibility of one single country, rather it is the responsibility of every spacefaring nation. Thankfully, now, there is a global consensus that the issue of space debris is starting to be of high concern. More debris will mean more collisions resulting in risks to orbital infrastructure and human crew in space. So, solutions must be put in place before the problem gets out of hand. This collective agreement among countries that space debris is a menace to space missions has led to several nations putting their best foot forward in helping to mitigate the situation.
To start with, in February 2022, certain member states of the United Nations Committee on the Peaceful Uses of Outer Space have pledged their services in helping to curb the proliferation of space debris. Portugal aims to do its part by leading the software and hardware development in space debris mitigation missions, such as the Active Debris Removal/In-orbit Servicing programme that focuses on de-orbiting/removing ESA debris pieces. Moreover, under the Collision Risk Estimation and Automated Mitigation programme by ESA, the nation is also in-charge of producing state-of-the-art machine learning and deep learning techniques to assist in automated avoidance maneuver decisions.
In the middle east, the Kingdom of Saudi Arabia, represented by the Saudi Space Authority, is steering the growth of sustainable space development. Since their governmental and private agencies have the capacity to monitor space and its objects, they have undertaken initiatives in establishing reports on space debris and in organizing research and workshops for the scientific community. In terms of space infrastructure owned by the kingdom, Saudi Arabia does not own space objects containing nuclear energy sources.
Apart from these pledges made, there have been committed efforts made by individual nations. China, for instance, has been utilizing their SJ-21 satellite for a sustainable environment in space. In a recent mission, towards the end of January 2022, the SJ-21 grappled the metal carcass of Compass-G2, a failed Chinese spacecraft, and flung it some 300 km away into a ‘graveyard’ orbit, where it will not be in the way of any other active space object. This method of literally picking up after their trash could become a viable solution for cleaning up orbital litter.
In a different approach to active debris removal, European Space Agency has contracted Swiss startup, ClearSpace, for a mission (scheduled for 2025) to deorbit a sizable Vespa payload adapter of the Arianespace Vega left in orbit from 2013. The spacecraft, built with four robotic arms, will seize the chunk of debris and haul it into the Earth’s atmosphere to burn up on reentry. Although this method may soon pose environmental concerns, it is a practical working solution for the time being.
In the commercial side of the space sector, private companies have also been undertaking projects for the mitigation of space debris. One notable example would be the recent startup, Privateer, led by Steve Wozniak. The organization’s focus lies on creating the data infrastructure to collect and process information regarding space objects that will eventually allow operators to safely conduct orbital maneuverings. At the moment, Privateer has kickstarted their mission with ‘Wayfinder’ — the company’s first application developed to provide an open-access and near real-time visualization of satellites and debris in our planet’s orbit. After all, before we can start clearing space debris, we have to be able to locate them in the first place.
In addition to existing debris removal plans and techniques, research is also being done to identify further effective methods to curb the space litter problem. Richard Klima, Daan Bloembergen, Rahul Savani, Karl Tuyls, Alexander Wittig, Andrei Sapera and Dario Izzo are the authors behind the research paper on applying game theory approach to understand active space debris removal. This will be executed through a stochastic game that involves space actors to strategise their decisions, the combination of which will determine the direction of developments of the space debris environment. The scenario will be replicated as a stochastic game in an improved high-fidelity orbital simulation that will provide insights into various centralized and decentralized solution methods to efficiently test the effects of various debris removal strategies.
At the end of the day, one thing is certain. Research and initiatives regarding sustainability in space operations and developments must continue in order to keep the space sector thriving. Many technologies we use on a daily basis need the assistance of satellites orbiting around our planet. Risking any damage to our space operations and infrastructure would mean disruption of daily life on Earth. As long as we send objects into orbit, the prevalence of space debris will continue to grow. But we must curb the problem to be one that is manageable to create a safe and sustainable space environment for future missions.