July 27, 2021

What is Space Sustainability & Why Does it Matter?

With space increasingly important for critical infrastructure, global efforts for space sustainability are needed to ensure access to orbit remains intact.

It’s easy to assume that events in orbit are of little consequence to life on Earth – that we don’t need to consider sustainability in the context of an endless universe. There are enough Environmental, Social, and Governance (ESG) concerns down here. Why bring space into the equation?   

But taking an out of sight, out of mind approach to Earth’s orbit could have serious repercussions. Low Earth Orbit (LEO) – the space approximately 160 km - 1,000 km above our planet – is home to vital infrastructure that we depend on around the clock, including communications, scientific, and military satellites.

Whether you’re navigating to the office, checking the weather forecast, or tapping into high-speed internet, you are using a network of satellites that are of huge importance, operating in LEO. The result of that reliance? This complex and dynamic operating arena is growing more challenging by the day as new satellites are launched.  

With space increasingly important for critical infrastructure, global efforts are needed to ensure access to orbit remains intact. 

The United Nations defines space sustainability as “the ability to maintain the conduct of space activities indefinitely into the future in a manner that realizes the objectives of equitable access to the benefits of the exploration and use of outer space for peaceful purposes, in order to meet the needs of the present generations while preserving the outer space environment for future generations.”

In short, action is required to ensure humanity can continue to use outer space for peaceful purposes and socioeconomic benefit, now and in the future. 

The nature of the domain means that for sustainability efforts to be successful, international cooperation, shared standards, and binding agreements need to be developed and adhered to.    

Threats to sustainable space operations

In addition to the growing number of satellites, there are arguably three threat categories facing sustainability in orbit: 

  • Increased debris, which left unchecked could render Earth’s orbit more challenging to access and operate in
  • Conflict and security concerns, which could cause further debris and an adversarial operating environment
  • Space weather events, which could damage hardware, cause more debris and/or conflict to escalate 


Most of the sustainability concerns in Earth’s orbit circle back to the number of objects up there. The scale of scientific, military, and commercial operations has grown exponentially in recent years, and that trend is set to continue as more satellite constellations head into orbit. 

Although much of this hardware is safely deorbited at the end of its operating lifecycle, a high proportion of the objects in orbit today are no longer active. Junk flying through space at 17,000 mph poses a significant risk to operational satellites, manned spaceflight missions, missions bound for elsewhere in the solar system, and other pieces of debris. Further collisions could lead to a cascade of crashes that renders LEO too crowded and dangerous to access, let alone use.  

In 2009, an inactive Russian Cosmos 2251 satellite collided with the active Iridium 33, creating more than 2,000 large debris fragments in the process. Many near misses have occurred since then. 

Satellite operators have to stay vigilant to prevent similar accidents from happening – a feat that will grow more challenging as the margin of error in orbit continues to shrink.  

Conflict and Tension in Orbit

As more countries send strategic and military hardware into orbit, space operations could become an attack vector. Satellite capabilities are vital for national security. It follows that interference with those satellites could spark or escalate a conflict.

There have already been several examples of anti-satellite tests carried out by China, Russia, and India, escalating the tension in orbit and adding plenty of debris in the process. Whether you view these as innocent tests or the orbital equivalent of a warning shot, the truth remains: conflict in space would significantly undermine long-term sustainability efforts. It must be avoided.

Space Weather

Weather from space, including solar flares and Coronal Mass Ejections (CMEs), can cause significant damage to satellites in orbit. 

These unpredictable incidents could lead to a significant build-up of debris, with satellites put out of action long before their planned end dates. Another superstorm is overdue, so it’s arguably a case of when, not if. 

Space weather could also damage hardware in such a way that operators don’t know whether the cause was an adversary or natural phenomena. It’s easy to imagine a scenario in which a false positive of an attack leads to conflict escalating between nations. 

How to make space more sustainable

Operational Transparency 

Earth’s orbit is a peculiar domain. To a degree, adversaries can see what each other are doing. What they may not know is the intention behind the action. 

In February 2020,  a US spy satellite was trailed by two Russian satellites, which had synchronized orbits, apparently in an effort to spy on the spy. Nothing came of the situation, but General John Raymond, the Space Force Chief of Space Operations, said “We view this behavior as unusual and disturbing. It has the potential to create a dangerous situation in space."

In May 2021, a Chinese rocket made an uncontrolled reentry into Earth’s atmosphere, eventually crashing into the Arabian Peninsula. The incident led to criticism from the wider space community and accusations that China’s space program was behaving carelessly. 

NASA Chief Bill Nelson said, "Spacefaring nations must minimize the risks to people and property on Earth of reentries of space objects and maximize transparency regarding those operations. It is clear that China is failing to meet responsible standards regarding its space debris. It is critical that China and all spacefaring nations and commercial entities act responsibly and transparently in space to ensure the safety, stability, security and long-term sustainability of outer space activities."

Both of these examples highlight the need for greater transparency in space. Better lines of communication will improve trust, lower tension, and ultimately increase the margin for error for all.

On-Orbit Servicing: RPOs, Active Cleanup Operations, and Sustainability Standards

There are thought to be at least 3,000 inactive satellites still in orbit. Many will eventually lose altitude and burn up in Earth’s atmosphere. For a significant proportion, a more active cleanup process is required. 

In March 2021, Japanese start-up Astroscale’s ELSA-d mission launched into orbit. It’s been described as “the world’s first commercial mission to prove the core technologies necessary for space debris docking and removal.”

The aim is to capture and safely remove space debris from orbit using magnetic retrieval, and prove concepts that, at scale, could prevent Earth’s orbit from becoming dangerously cluttered. 

One obvious way to reduce the amount of junk in Earth’s orbit is to extend the life of current satellites. Recent advances in Rendezvous and Proximity Operations (RPO) capabilities – which include on-orbit inspections, repairs, refueling, assembly, and manufacturing – hold significant promise. 

Companies including Maxar, Astroscale, and Orbit Fab are developing solutions that will have a huge impact on space sustainability.   

The challenge for these service providers and RPO technology moving forward is verifying intent. Governments, space agencies, and commercial entities on the ground need to be able to distinguish legitimate RPO actions from hostile ones. 

For that to happen, space stakeholders need to come together to develop standards and norms of behavior that govern RPOs and active cleanup operations.  

And until those servicing and de-orbiting solutions are widespread, it’s incumbent upon those stakeholders to launch satellites with sustainable deorbiting designs in mind.   

Enhanced Situational Awareness

On top of the exponential growth in global launch activity and debris complications, operations in orbit are enhanced by data fused from multiple sources to make mission-critical decisions.

Smarter space traffic management is vital. In order to enhance situational awareness where it’s needed most, Slingshot Aerospace brings the space domain into the digital environment. By fusing data from different sources, government and commercial space organizations are empowered to better manage and safeguard their assets, mitigate risk, and improve the reliability of operations.  

Efforts to achieve clarity in orbit will lead to fewer mission-critical mistakes, more efficient operations, and a reduction in collisions and anomalies that might threaten the sustainability of the wider orbital environment. 

Better Weather Forecasting 

Most of the sustainability challenges in orbit result from the increased demand for satellite hardware and a lack of shared deorbiting standards in years gone by. But the threat of damaging space weather is one that’s harder to predict and monitor.   

Global efforts are needed to devise engineering standards with space weather in mind, as well as continued collaboration on research, risk management, and forecasting programs. 

Fortunately, the scientific community studying these phenomena has long been sharing data and working to build a more detailed picture of the weather in space. 

The challenges posed by space weather inspired the forming of Aerospace’s Center for Assessing Space-weather Impacts and Innovation (CASII), the European Space Agency’s Space Weather Network, and global programs such as GONG, a worldwide network of telescopes that observe the sun around the clock. 

In February 2020, a joint NASA and ESA mission launched the Solar Orbiter, a spacecraft dedicated to furthering our understanding of solar and heliospheric physics. The mission’s many scientific instruments are already providing unprecedented data for collaborative space weather investigations here on Earth. 

Endeavors such as this, as well as those by our partners Spire and NOAA, enhance our collective understanding of space weather. Moving forward, they enable the architects of infrastructure in orbit to make smarter decisions and keep operations running smoothly.  

Space Sustainability is a Process

Keeping Earth’s orbit a sustainable environment should be a key priority for any organization with a vested interest in access to space. 

But developing shared sustainability standards in a domain so complex and competitive isn’t easy. There are initiatives being developed, such as the Space Sustainability Rating (SSR), that aim to resolve this. SSR was first introduced at the World Economic Forum Global Future Council on Space Technologies. The rating system was developed by an international group that includes the MIT Media Lab, European Space Agency, the University of Texas, and Bryce Space and Technology.

When assessing a mission plan, SSR accounts for on-orbit fragmentation risk, collision avoidance capabilities, detectability, identification, trackability, data sharing, on-orbit servicing, collision avoidance, debris mitigation, and more. The goal is to incentivize sustainable mission design. However, there are many factors to consider and measure, so the jury is still out.

Just like at ground level, a sustainable future in space is a feasible and necessary step. There are incredible private sector opportunities in Earth’s orbit, but every mission has a responsibility to protect and secure the environment for the future.