## 3 Legal Challenges Posed by Mega-Constellations to Existing International Space Law Regime
### Environmental Sustainability  
Article 3 of the Outer Space Treaty states that space activities should be carried out in accordance with international law; this Article is all-inclusive and thus has no limitations regarding which international laws apply [40]. Therefore, environmental sustainability laws, although often flaunted in the pursuit of the rapid deployment of mega-constellations, do apply in this instance. Under the Outer Space Treaty's principle of \"due regard\" for others' interests, states may be required to conduct environmental impact assessments before approving mega-constellations. However, this is not an explicit requirement. Furthermore, despite the 1992 Rio Declaration's [39; 41] emphasis on sustainable development, the space industry lacks rigorous environmental regulations, leading to potential long-term ecological impacts. Recent studies highlight the urgent need for comprehensive environmental standards specific to space activities ([PERSON], 2019) [41; 42]. The proliferation of space activities, especially the deployment of mega-constellations, raises significant concerns regarding environmental sustainability. While the Liability Convention addresses physical damage, it falls short in considering the environmental harm caused by space debris. Space debris, essentially a form of pollution, threatens the space environment since there is a possibility of increased space pollution from combustion by-products, which is accumulated in space and can alter the chemical composition of the near-Earth atmosphere, leading to contamination. Furthermore, space debris also leads to the Kessler syndrome, impacting future space activities, which necessitates a more comprehensive approach to include environmental damage within the legal framework. The environmental impact of increased space launches is multifaceted. Firstly, the reentry of space debris poses risks of environmental contamination through the release of nitrogen oxides, which, based on a study by [PERSON] et al. (2022), can contaminate the environment [43], including soil and water [44; 45]. Secondly, biological contamination cannot be ruled out, as the introduction of terrestrial microorganisms into outer space or the return of extraterrestrial materials to Earth can have unforeseen consequences,such as posing a significant risk of contamination during space missions from terrestrial microorganisms in spacecraft [46]. There are also risks of biological contamination from the return of extraterrestrial materials, as found in a study by [PERSON] et al. (2011) [47], and forward contamination during lunar missions, as it could compromise life detection missions [48], underlining the necessity for tight precautions to prevent contamination [49]. Moreover, the potential loss of scientific evidence about the solar system due to increased space debris also undermines the scientific value of outer space in the sense that space debris collisions with spacecraft or instruments like probes, landers, or telescopes [50] used to study the solar system could cause damage. The same applies to the exploration of the solar system, which would be hazardous in the face of space debris [51]. Furthermore, solar phenomena observations like the Maunder minimum and the grand minimum, which are believed to have an influence on the amount of debris, may be difficult to study as a result of this debris. Therefore, the study by [PERSON] (2023) [44] emphasizes the need to address the environmental impacts of space activities, including the reduction of space debris [48], and NASA (2020) [52] has highlighted the importance of preserving the scientific integrity of space missions by minimizing contamination and ensuring the accuracy of the data collected [53]. Furthermore, the multinational nature of commercial space activities complicates the enforcement of environmental laws, since ownership transfers and the involvement of multiple jurisdictions make it challenging to establish and enforce environmental regulations effectively. For instance, a study by [PERSON] et al.