1.2 State of the Field and Identified Normative Gap
1.2.1 The Physical and Regulatory Context
Space object reentry is built into the planned lifecycle of many current and future space objects. As the “end-of-life” solution for defunct satellites and even space stations, large pieces of debris re-enter on both controlled and uncontrolled trajectories that frequently terminate in the high seas. Toxic chemicals, including unspent fuel, and other materials are deposited upon impact directly into oceanic ecosystems which are often understudied and poorly understood.(1) Kaineg, Sophie. "The Growing Problem of Space Debris," Hastings Environmental Law Journal26 (2020): 277.
The governing legal architecture derives from two discrete regimes. International space law, anchored in the 1967 Outer Space Treaty (OST) and the 1972 Liability Convention primarily addresses post-impact compensation rather than prevention or mitigation.(2)Convention on International Liability for Damage Caused by Space Objects. Opened for signature March 29, 1972, entered into force September 1, 1972, 961 U.N.T.S. 187. Article VII OST(3) Outer Space Treaty, art. VII. and the Liability Convention impose either fault-based liability (for damage in outer space or airspace) or absolute liability (for damage on Earth's surface or to aircraft) on "launching States." These are defined as States that launch or procure the launch of a space object, or from whose territory or facility the launch occurs, and constitutes a pecuniary regime oriented toward damage redress.(4) Liability Convention, art. I(c).
Distinctly, Article VI OST establishes broader State responsibility for all "national activities in outer space," whether governmental or non-governmental.(5) Outer Space Treaty, art. VI. It requires authorisation and continuing supervision to ensure conformity with the OST. This conduct-based duty imputes wrongful acts to the State irrespective of actual damage. Consequently, potential EIA obligations under the BBNJ may vest in both launching States (per the Liability Convention's scope) and authorising/supervising States (per Article VI). Detailed delineation of these regimes, however, falls outside this thesis's scope, which limits analysis to establishing the attribution baseline for marine impacts.
The OST’s Article IX, which requires states to pursue activities “with due regard” for the interests of others and to avoid “harmful contamination” of outer space, was drafted with the space environment in mind and has not extended to reentry's marine environmental consequences.(6) Outer Space Treaty, art. IX.
1.2.2 The Role of UNCLOS and Customary International Law
UNCLOS Articles 192 and 194 impose obligations to protect and preserve the marine environment and to take all measures necessary to prevent pollution from “any source.” The breadth of that language is arguably capable of capturing satellite splashdowns and reentry debris. Yet state practice has not systematically applied these provisions to space-related activities, and the treaty’s jurisdictional framework, which divides the oceans into zones of varying state authority, creates ambiguity where the high seas are concerned.
The International Court of Justice, in Pulp Mills on the River Uruguay (2010), affirmed that the obligation to conduct an EIA before undertaking activities with potential significant transboundary environmental harm has crystallised as a rule of customary international law.(7) Pulp Mills, Judgment, I.C.J. Reports 2010, p. 14, https://www.icj-cij.org/case/135. This obligation is not contingent on any specific treaty regime. Whether routine splashdown operations fall within its scope, given their transboundary character and potential for significant environmental impact, is a question that requires additional systematic legal analysis.
1.2.3 The Normative Gap
This thesis examines a structural, rather than merely procedural, normative gap arising at the intersection of international space law and the law of the sea: the descent of space objects from one global commons into another exposes the failure of their respective legal frameworks to address one another coherently. This paper argues that the BBNJ's recent entry into force offers the opportunity to better address and clarify this gap.
The normative gap identified in Section 1.2 operates on three distinct dimensions, each addressed in turn in Parts 2 and 3. The first is a jurisdictional gap. International space law allocates responsibility through the concept of the "launching State,"(8) Outer Space Treaty, arts. VI, VIII. which retains jurisdiction and control over a space object throughout its operational life.(9)Convention on Registration of Objects Launched into Outer Space, adopted November 14, 1974, entered into force September 15, 1976, 1023 U.N.T.S. 15, art. II. As Cheng has demonstrated, however, the attribution of "international responsibility" under Article VI OST to the "appropriate State" for a given "national activity" is not straightforward: the treaty text does not define what constitutes a national activity, nor does it identify with precision which State is the "appropriate State" responsible for authorising and supervising it.(10) Bin Cheng, "Article VI of the 1967 Space Treaty Revisited: 'International Responsibility', 'National Activities' and 'the Appropriate State'," Journal of Space Law26 (1998): 7–15. The law of the sea allocates responsibility through the concept of the flag State and, more broadly, through the State exercising “jurisdiction or control” over an activity. These categories are analogous but not identical, and their overlap in the splashdown context has, to date, never been authoritatively resolved. A State may be the launching State under the OST without being the licensing State for the activity’s oceanic phase, and vice versa; leaving open the possibility that no single State bears unambiguous legal responsibility for the marine environmental consequences of a controlled reentry.
The second dimension is substantive. The OST framework imposes no obligation to assess, mitigate, or monitor the marine environmental impacts of splashdown operations. The UNCOPUOS Space Debris Mitigation Guidelines(11) United Nations Committee on the Peaceful Uses of Outer Space, Space Debris Mitigation Guidelines of the Committee on the Peaceful Uses of Outer Space(Vienna: United Nations, 2010), UN Doc. A/62/20, annex. and the IADC guidelines(12) Inter-Agency Space Debris Coordination Committee (IADC), IADC Space Debris Mitigation Guidelines, IADC-02-01 (rev. 2021). address orbital sustainability and casualty risk to people and property on the Earth’s surface. These non-binding recommendations define remote ocean areas as the safest available disposal option precisely because no human beings live there, not because the marine environment is protected. The 2025 revision of the IADC Guidelines gestures toward environmental concerns for the first time, acknowledging that ground environmental pollution from reentries “should be prevented or minimized,” yet provides neither binding standards nor implementation mechanisms.(13) Inter-Agency Space Debris Coordination Committee (IADC), IADC Space Debris Mitigation Guidelines(2025 revision), UN Doc. A/AC.105/C.1/2025/CRP.9, accessed April 3, 2026, https://www.unoosa.org/res/oosadoc/data/documents/2025/aac_105c_12025crp/aac_105c_12025crp_9_0_html. The result is that the single most heavily used spacecraft graveyard on Earth, the South Pacific Oceanic Uninhabited Area, where over 260 space objects have been deposited since the 1970s,(14) Chelsea Muñoz-Patchen, "Regulating the Space Commons: Treating Space Debris as Abandoned Property in Violation of the Outer Space Treaty," Chicago Journal of International Law 19, no. 1 (2018): 233–59, https://chicagounbound.uchicago.edu/cjil/vol19/iss1/7. has never been the subject of a systematic environmental assessment under any applicable legal framework.(15) García, “The Spacecraft Cemetery at the Loneliest Point on Earth.”
The third dimension is institutional. UNCOPUOS and UN Office for Outer Space Affairs (UNOOSA) carry no marine environmental mandate, while UNCLOS and the BBNJ govern ABNJ with no formal interface to the space governance regime. The absence of any joint body, information-sharing mechanism, or coordination process compounds the substantive gap, producing an absence of data, applicable standards, and oversight at the precise intersection that demands all three.
The urgency of addressing this gap is compounded by two concurrent developments. First, the volume of space activity, and with it, the frequency of splashdown operations, is increasing exponentially. SpaceX’s Starlink megaconstellation alone accounts for approximately forty per cent of current satellite reentries;(16) Tereza Pultarova, "How Much Do SpaceX’s Reentering Starlink Satellites Pollute Earth’s Atmosphere?," Space.com, October 17, 2024, https://www.space.com/spacex-starlink-reentry-pollution-damage-earth-atmosphere. and the planned 2030 deorbit of the International Space Station represents a litmus test for the governance gap at a scale that cannot be ignored.(17) “What Is Point Nemo, the Remote, Watery Satellite Graveyard Where the ISS Will Go to Die?,” Live Science, December 1, 2023, https://www.livescience.com/planet-earth/rivers-oceans/what-is-point-nemo-the-remote-watery-satellite-graveyard-where-the-iss-will-go-to-die. Second, understanding of the fragility and ecological significance of deep-sea ecosystems has advanced considerably since the OST was adopted in 1967. The continued usage of the spacecraft cemetery at Point Nemo is based on the assumption the area is an ecological void. As scientific understanding of deep-ocean environments improves, such claims warrant urgent reexamination with particular attention to the possible cumulative contamination introduced by more than half a century of unmonitored debris deposits. The BBNJ’s entry into force provides the legal mechanism through which this intersection of increasing activity and increasing knowledge can be properly governed.