Space exploration – Is it sustainable?

8 minute read
05 January 2024

The world's first successful satellite launch occurred in October 1957, when the USSR launched the Sputnik 1 satellite. Since then, humans have continued to launch satellites and spacecraft into space for the purposes of exploration, weather forecasting, television signalling and data gathering on the Earth and solar system (among others) – but not all of it makes its way back to earth.

In this article we consider the issue of "space junk", review the laws of space, question whether space exploration is sustainable, and explore opportunities for improvement.

What is space junk?

Space junk is perhaps best defined by Dr Mark Matney of NASA's Orbital Debris Program Office, who described it as "any human-made object that no longer serves a useful function in space".[1] This can incorporate inactive satellites, debris from spacecraft and launch adapters.

In November 2023, the European Space Agency estimated that there are 130 million pieces of space debris larger than a millimetre that are orbiting the Earth.[2] Some of this debris is created when abandoned spacecraft explode as a result of leftover energy sources, such as residual fuel, left on board. Much of the trackable debris in the Earth's orbit results from collisions, with over half of the trackable space debris in the Earth's orbit arising from the Chinese anti-satellite test in 2007, and the Russian-American satellite collision in 2009.

How does this affect Earth and why does it matter?

We have all heard the old adage, "what goes up must come down". While that's not strictly true when it comes to launching objects into space, falling debris still poses a significant risk. NASA estimates that a piece of debris falls from space, back to Earth, daily.[3] While some pieces of debris will be incinerated as they return to the Earth's atmosphere, others will land back on Earth. The US's Federal Aviation Administration released a report in October 2023 that indicated that such debris could injure or kill someone on Earth every two years by 2035, and of course there could be significant and regular damage to property and the environment.[4]

Space junk moves rapidly – at speeds of up to five miles per second, or 18,000 miles per hour.[5] This means that the debris in space can cause substantial damage to active satellites. This can have sustainability implications as collisions between satellites can result in the release of hazardous chemicals into the Earth's atmosphere, diminishing the ozone layer.

The Federal Communications Commission (FCC) recently fined DISH Network Corporation $150,000 (£125,000) for failing to move an old satellite far enough away from others in use. DISH Network's dead satellite posed a potential risk to other active satellites orbiting the Earth at its current altitude. This is the first time the FCC have enforced their regulatory powers so it is likely the rest of the industry will be more conscious of their own space junk.[6]

With space agencies and private companies continuing to launch items into space (including Elon Musk's Space X, which launched 12 missions between 1 July and 31 August 2023),[7] the increasing amount of debris surrounding the Earth increases the probability that "Kessler syndrome" will occur. This phenomenon occurs when the amount of space debris reaches a level whereby collisions increase rapidly, setting off a positive feedback loop that results in further collisions. This places active satellites at risk, which may inhibit our ability to forecast weather and monitor changes in the Earth's climate.

While the amount of space junk in the Earth's atmosphere is steadily increasing, continual growth in the amount of space junk in the Earth's orbit is avoidable. The European Space Agency suggested in 2020 that less than 60% of operators of satellites in the low-Earth orbit adhere to their guidelines (which include avoiding intentional debris generation and minimising potential explosions).[8] Encouraging increased compliance with such guidelines and introducing sanctions for those who fail to comply may motivate operators of satellites and other spacecraft to limit the amount of space junk they abandon, but guidelines alone may prove to be insufficient.

Are there any laws governing space?[9] [10] [11]

There are five significant international treaties, agreements and conventions, commonly referred to as the "Five United Nations Treaties on Outer Space", which underpin space law. These have been developed over time and are overseen by the United Nations Committee on the Peaceful Uses of Outer Space. Over the years, many countries have introduced national legislation governing space-related activities. However, notably, there is no claim for sovereignty in space which means that no nation can claim ownership of space, the Moon or any other space body. The Five United Nations Treaties on Outer Space address a variety of matters and enforce a number of fundamental principles in relation to the conduct of space related activities.

The Outer Space Treaty[12]

The Outer Space Treaty came into force in October 1967 and provides the basic framework of international space law. The Outer Space Treaty highlights key principles governing the activities of states in the exploration and use of outer space, including the Moon and other celestial bodies. For example, space activities are for the benefit of all nations and any country is free to explore orbit and beyond. Another example is that any astronaut from any nation is an “envoy of mankind”.

The Rescue Agreement[13]

The Rescue Agreement came into force in December 1968 and provides that signatory states agree to help or rescue astronauts in need, regardless of the nation the astronaut is from. If applicable, this may mean assisting with the return of the astronaut back to the nation from which they launched. In addition, the Rescue Agreement also provides that the signatory states agree to help return any space objects (to the sponsoring nation) that land on Earth outside of the country from which they were launched.

The Liability Convention[14]

The Liability Convention came into force in September 1972 and provides that signatory states take full liability for any damage caused by their space objects and agree to standard procedures for adjudicating damage claims. Ultimately, signatory states are responsible for their own space activities.

The Registration Convention[15]

The Registration Convention came into force in September 1976 and empowers the UN Secretary-General to maintain a register of all space objects.

The Moon Agreement[16]

The Moon Agreement came into force in July 1984 and provides that celestial bodies can only be used for peaceful purposes (weapons of mass destruction are strictly forbidden) and must not be contaminated.

Each of the Five United Nations Treaties on Outer Space present individual principles on space-related activities but they all share the common emphasis on encouraging international cooperation.

What can be done about space junk?

Most of the current effort to remove orbital debris is still focused on the mitigation and reduction of space junk production[17]. Different ideas, aiming at more direct removal action, have also been floated in the recent years. The vast majority of techniques currently contemplated to actively remove space debris entail the use of a new satellite to remove existing ones, with the notable exception of ground-based lasers – which could also shift the debris' orbit into the atmosphere.[18]

The UK Space Agency announced in 2022 that the UK divisions of two overseas companies, ClearSpace (Switzerland) and Astroscale (Japan), were designing missions to space in order to clear orbital debris. Together, these companies were awarded £4 million to support their work and could be awarded further funding, with the hope of seeing the first UK space junk cleaning mission launch in 2026.[19]

End-of-Life by Astroscale-demonstration (ELSA-d) is one of these promising developments. This magnetic capture system was launched on 22 March 2021 and seeks to gradually lower the orbit of client satellites until they can re-enter the earth's atmosphere and burn up.[20] Detailed plans for the final phase of the ELSA-d's mission were announced a few months ago, showing hope for the pursuit of space sustainability.

In parallel, NASA recently awarded $850,000 to a start-up developing an inflatable bag initially designed for asteroid mining, but which they later realised could be utilised to capture debris within the Earth's orbit.[21]

Could space exploration be sustainable one day?

The main points of resistance to the capture of space junk lie in the fact that the techniques are costly to develop and use. In addition, some observers have raised caution as to the fact that these initiatives run the risk of interfering with geopolitical sensitivities, especially in terms of defence and militarisation of space.[22]

A silver lining could, however, come from the fact that whilst space debris removal is in its very conceptual and early stages, there is cautious but growing hope that it may also start generating commercial demand over time; much like space exploration and Earth observation missions did in their time too.[23]

How can we help?

Gowling WLG is an international law firm with the insight and experience to help you launch your business towards your commercial goals, navigate through a dynamic legislative and regulatory landscape and take the giant leap towards your business' full potential.

If you need help navigating the evolving world of sustainability and environmental law, please contact Ben Stansfield. If you need advice in relation to aviation, aerospace and defence, please reach out to Elizabeth Williams. If you would like to discuss your requirements in the technology sector, please contact Alexandra Brodie or David Brennan.

If you have any questions about this article, contact Yasmin Samaroo, Charles Couvreur or Annabelle Percy.


[1] Houston We Have a Podcast - Episode 221 - Orbital Debris

[2] World-first Zero Debris Charter goes live

[3] What Is Orbital Debris? (Grades 5-8)

[4] Risk Associated with Reentry Disposal of Satellites from Proposed Large Constellations

[5] Risk Associated with Reentry Disposal of Satellites from Proposed Large Constellations

[6] US issues first ever fine for space junk to Dish Network

[7] Orbital Debris Quarterly News - Volume 27, Issue 4 - October 2023

[8] The cost of space debris

[9] Space Law Treaties and Principles

[10] Space briefing book: Space Law

[11] United Nations Office for Outer Space Affairs - Space Law

[12] The Outer Space Treaty (

[13] Rescue Agreement (

[14] Liability Convention (

[15] Registration Convention (

[16] Moon Agreement (

[17] Who's going to fix the space junk problem?

[18] Who's going to fix the space junk problem?

[19] UK builds leadership in space debris removal and in-orbit manufacturing with national mission and funding boost

[20] Astroscale’s ELSA-d Gears Up for Controlled De-orbit During Final Mission Phase

[21] TransAstra claims NASA contract for debris capture bag

[22] Who's going to fix the space junk problem?

[23] Taking out the trash: Here's how private companies could be vital for space debris removal

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