The Northumbria University Law School is home to an expert Space Law Team researching on current legal issues and challenges in Earth’s orbits, on celestial bodies, and across tech such as governance challenges regarding cybersecurity or the use of AI with satellite systems. The Law School also hosts various space law and regulating tech modules at the undergraduate and master’s levels. The Law School includes two Space Law LLM Programmes: Space Law LLM (full-time) and Space Law LLM (part-time, distance learning). To learn more about space law at the Northumbria University Law School please visit: https://www.northumbria.ac.uk/
Leave No Trace, is it the Same for Space?: Planetary Protection and Surface Space Waste.
Georgia Brown, Space Law LLM Student, Northumbria University
https://bsky.app/profile/astrologee.bsky.social
Under Article IX of the Outer Space Treaty (1), the exploration and use of celestial bodies must be conducted in a manner to ‘avoid their harmful contamination’. The Outer Space Treaty was written in 1967 and remains the primary source of binding international law. Whilst it does not mention sustainability or planetary protection directly, it does attempt to protect celestial bodies in Article IX. This is especially important in the search for extraterrestrial life, and sterile equipment prevents what scientists describe as ‘forward contamination’. However, if the equipment sent to celestial environments is sterile, then it seems that there is no legal requirement to remove this debris as there is no risk for contamination, which raises the question of what the standard of ‘harmful contamination’ is or should be. In this article I will consider the value of a ‘leave no trace approach’ in space activities and despite its imperfections in practice, can promote sustainable and responsible behaviours of space actors.
In principle, the chances that we can ever conduct an entirely ‘leave no trace’ mission in outer space are very slim. Whether it is craters created on impact or airbags, heatshields and parachutes, the very nature of planetary exploration currently involves the use of objects designed to be used only once. Celestial bodies in our solar system have had an increasing amount of waste and remnants left over from missions; from 96 bags of human waste on the Moon to spacecraft debris on Mars and Titan, Saturn’s largest moon.
Typically, objects have remained on celestial surfaces due to technical difficulties and high expense involved with a removal mission. Although space exploration has become more affordable since the Cassini-Huygens mission (1997-2017), which explored Saturn and it’s moons at a cost of $3.9 Billion, a return trip would have required a substantial addition to the cost and time to return the craft when it had carried out its role. There are a number of other examples such as the proposed Mars sample return mission that demonstrate similar difficulties. This piece argues that whilst we do not have an explicit legal obligation, we do have a moral responsibility to remove waste and debris from celestial surfaces. It will demonstrate that whilst leave no trace may be technically infeasible, it is an important standard to strive for as space activities evolve.
Since the Apollo missions, the Moon has become a site that has been littered with all sorts of detritus. There are flags of many nations, personal photographs, plaques, golf balls, moon buggies and ashes. Some argue that these objects represent the ‘unparalleled human achievement’of the exploration of the Moon. The United States has even passed a bill for NASA to protect the Apollo landing sites in the One Small Step to Protect Human Heritage in Space Act. The question arises of how should we categorise objects on celestial surfaces, as either protected artefacts or as waste? This is increasingly important as the next manned mission to the Moon approaches, projected to launch April 2026. Will there be any rules for what these 4 astronauts can or cannot leave on the Moon?
Additionally, the surface of Mars there are 8 landers, 6 rovers and countless tonnes of disposed parts and equipment that has accumulated over the years. Saturn’s moon, Titan also became the forever home of NASA’s Huygens probe, part of the Cassini-Huygens mission which launched in 1997. As scientific and planetary exploration into our solar system continues to develop, it is essential to discuss the legal and ethical concerns involved with the protection of these environments. How much waste is too much waste on these surfaces or is it an out of sight, out of mind scenario?
A common misconception about space law is that the Outer Space Treaty only applies to States. However, under Article VI, it outlines that non-governmental and private entities are under the national responsibility of the State. Therefore, all space activities have a degree of responsibility, and no one is exempt. The issue lies in the enforcement capabilities, or rather the lack of such mechanisms. A problem not unique to space law, international law often struggles with enforcement as there is no international police or space law prosecution body. In 2019, an Israeli company sent an unmanned space probe to the Moon. Due to technical faults, the craft crash landed, scattering its contents over the lunar surface, including tardigrades. Tardigrades, also known as water bears, are microorganisms that are known to survive, or even thrive, in extreme environments. Not only were the Israeli government not disclosed the details regarding the tardigrades on board prior to launch, but the company faced no sanctions. The act presented biological matter to an extraterrestrial environment and could be considered as ‘harmful contamination’ under Article IX of the Outer Space Treaty. Whilst international space law attempts to address responsibility in space activities, there are concerns over the regulation of space activities that could have detrimental effect on celestial environments.
Non-binding (soft) law also considers celestial environmental protection. The Committee on Space Research (COSPAR) released the Planetary Protection Policy in 2024. These guidelines focus on the biological and organic contamination of the vehicle or materials and the risk this poses. Whilst biocontamination is incredibly important at preserving the ‘pristine’ environment as well as protecting potential extraterrestrial life and associated research, the guidelines disregard inactive vehicles or equipment and litter on the surface. The stress on biological contamination might even excuse the build-up of debris on surfaces such as the Moon which are considered absent of life.
So, what obligation do we as humans have to keep celestial surfaces free of discarded objects, if it is too technical and expensive to remove, legal, and does not pose biocontamination threats?
Whilst it can be argued we have no legal obligation, it is argued here we have a moral obligation to prevent the build-up of waste on planetary surfaces. As we have seen with Earth’s environment and increasingly with satellite congestion in Low Earth Orbit (LEO), humankind can have a tendency to abuse environments we have access to. Crowding in LEO has grown exponentially over recent years. In 2020, it was reported that there were 3256 satellites compared to early 2025 where there are 9325 active payloads in LEO, 6935 of which are SpaceX privately owned Starlink satellites. This 184% increase over the past 5 years is alarming, especially considering these numbers do not include inactive satellites and payloads, untracked smaller debris fragments and objects in Medium-Earth orbit (MEO) and Geostationary orbit (GEO). Orbital congestion now also poses further problems such as equitable access, frequency allocation, de-orbiting as well as the likelihood collision events causing further fragmentation of debris. As the issue grows, cleaning it up is increasing challenging. As we continue to venture further deeper space, we must ensure that we adopt responsible practices to protect the environments we explore.
The concern of the build-up of waste on other celestial bodies, including LEO, also raises concerns over territorial claims in outer space which is prohibited under Article II of the Outer Space Treaty. The article outlines that celestial bodies are “not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.” The question is if Starlink owns 74% of active satellites currently in LEO, does Starlink have any ownership over the space these satellites occupy? Furthermore, Elon Musk is vocal about his intentions to create a human colony on Mars in the next decade, intensified in President Trump’s inauguration speech vowing to ‘plant the stars and stripes on the planet Mars’. Even if these projects never come to fruition, it’s important to evaluate the current legislation in place if it did.
As exploration in outer space progresses, it is necessary that we adopt responsible and sustainable practices, legislation and norms to ensure we do not run the risk of sustainability challenges similar to those we currently face on Earth and LEO.
Reference list:
‘For All Moonkind’ (For All Moonkind, 2023) <https://www.forallmoonkind.org/> accessed 14 February 2025
Horváth P, ‘Sterilisation for Planetary Protection’ (European Space Agency, 2 April 2020) <https://www.esa.int/ESA_Multimedia/Images/2020/04/Sterilisation_for_planetary_protection> accessed 7 February 2025
‘MAN MADE OBJECTS ON MARS’ (Space Artefacts) <https://spaceartefacts.com/human-objects-on-mars> accessed 7 February 2025
McDowell J, ‘Jonathan’s Space Report | Space Statistics’ (Satellite statistics: Satellite and Debris Population, 2 February 2025) <https://planet4589.org/space/stats/active.html> accessed 6 February 2025
NASA, ‘Artemis II – NASA’ (NASA) <https://www.nasa.gov/mission/artemis-ii/> accessed 7 February 2025
NASA, ‘Cassini’ (NASA, 3 November 2024) <https://science.nasa.gov/mission/cassini/quick-facts/> accessed 7 February 2025
Olsson-Francis K and others, ‘The COSPAR Planetary Protection Policy for Robotic Missions to Mars: A Review of Current Scientific Knowledge and Future Perspectives’ (2023) 36 Life Sciences in Space Research 27
Palka L, ‘What Likely Happened to the Tardigrades Sent to the Moon in 2019’ (Astronomy, 28 February 2024) <https://www.astronomy.com/space-exploration/what-happened-to-those-tardigrades-sent-to-the-moon/> accessed 6 February 2025
Royal Museums Greenwich, ‘The Strange Things Humans Have Left on the Moon’ (Royal Museums Greenwich) <https://www.rmg.co.uk/stories/topics/strange-things-humans-have-left-on-moon> accessed 7 February 2025
Sen. Peters GC [D-M, S.1694 – 116th Congress (2019-2020): One Small Step to Protect Human Heritage in Space Act 2020 [S.1694]
Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (adopted 27 January 1967, entered into force 10 October 1967) 610 UNTS 205
UK Government. ‘The Future Space Environment’ (GOV.UK, 16 May 2024) <https://www.gov.uk/government/news/the-future-space-environment> accessed 6 February 2025.
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