How can we control space pollution?

The space environment is undergoing a profound transformation, with new missions to populate the Moon, travel to Mars, explore life science in space greenhouses, carry out zero gravity molecule experiments, and enjoy space tourism. The sky is being reshaped by an increasing number of satellites, including nano satellites and constellations for communications in Low Orbit. The number of space missions is growing exponentially and at the same time, so is space debris. This growth in space debris not only increases the risk of potential danger to space vehicles with humans on board but also to Earth, with several hundreds of objects expected to eventually re-enter the atmosphere. Everybody remembers the stress of the Dragon 2 Crew’s space debris "event" that forced the ISS crew to take evasive action in November 2021. 

More than 34,000 pieces of orbital debris above 10cm in size, also known as space junk, are currently being tracked by the European Space Agency (ESA) and the Department of Defense’s global Space Surveillance Network (SSN) sensors. Considerably more debris between one and 10cm - too small to be tracked but large enough to threaten human spaceflight and robotic missions - exists in the near-Earth space environment. Most of the debris is located at an altitude of between 600 and 900km - the equivalent of ‘next door.’ Since both this debris and spacecraft are traveling at extremely high speeds - approximately 17,500 mph/28,163 kph in low Earth orbit – the impact of even a tiny piece of space junk could create significant challenges for a spacecraft. Even tiny paint flecks can damage a spacecraft when traveling at this velocity.

The technical challenges are incredible. The first test is to find the debris. How do we detect a 2cm fragment moving at 17,500 mph/28,163 kph? There are two means of detection – one on the ground and one in orbit. But both must be coupled with trajectory calculation analysis to determine the “if, when, and where” of the potential POI (Point of Impact). Research has been ongoing for many years to not only detect but also collect, destroy, or deviate this debris from its trajectory. 

Several anti-debris systems are emerging: from a “vacuum cleaner” to a net, magnet, and Pacman or punching system. The five following techniques are currently under development:

1 — One such solution is a “laser gun,” which partially burns an old satellite via laser, causing it to fragment into many pieces. This action will change the course of the satellite, sending it into the atmosphere, where it will disintegrate. However, the problem is that solar panels could “spread” themselves into new particles during the operation, which would be nearly impossible to clean. Moreover, this technique must be operated by a space laser which could generate new debris of its own. 

2 — A magnetic “tug” – a satellite with electro-magnetic properties – is also under study. This solution would follow the debris at a distance of 10-15m, from where the magnet would deviate the debris and push it back into the atmosphere to facilitate the burning process. 

3 — In 2018, the UK‘s Surrey Space Centre launched a satellite called RemoveDebris, which launched a net to collect even the smallest parts of debris at an altitude of 300km. In 2019 it used a harpoon to fetch larger debris. 

4 — Financed by ESA and built by a Swiss startup, CleanSpace One will be tested in 2025. Working at an altitude of 600km, this flying box will open its legs like a spider and capture a satellite by putting those legs around it and dropping it into the atmosphere for a burning funeral.

5 — Finally, the most promising study is that of a self-destructible, sustainable satellite.

All of these developments are currently happening without any international legal framework. Instead, they are following an informal code of conduct. NASA published guidelines in 1995 (NSS-1740.14), followed by the French CNES and the European Union in 2004.  

But, if the international community doesn’t rapidly adopt international legislation as it has with the sea – the Montego Bay Treaty – Space could soon become the next Wild West.

Part of the “decluttering” solution lies in the design and operation of constellation satellites which will minimize the likelihood of orbital collision during operations. New nano-satellites must be made to be self-destructible and burn up in the atmosphere at the end of their lifetime. Lignosat, the first satellite made partially of wood, will be launched in 2024.

The domain of space has undergone a massive revolution in the last ten years due to reusable launchers and new business models, and it is still evolving at light speed. Many space players - particularly the numerous start-ups popping up - are paving the way for new businesses. The sky is no longer the limit, and “Houston, we are going to clean the problem.”

Related resources:

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• Innovation takes stamina - Research & Innovation at Capgemini Engineering