As human settlements
on celestial bodies and the exploitation of space resources become priorities
for space-faring nations, the need to protect the sustainability of outer space
is growing. States have begun introducing requirements to pursue sustainability
in the use and exploration of outer space. This paper addresses environmental
impact assessment (EIA) in the context of in-orbit activities. It provides an
analysis of the obligations of states under the Outer Space Treaty (OST) and
international environmental law to establish whether there is an obligation to
conduct an EIA. To support this analysis, it reviews existing national
regulations requiring an EIA. The aim is to determine how states have
integrated EIAs into their regulatory frameworks and to clarify their scope,
particularly whether EIAs must include impact on the outer space environment or
only those on Earth. In addition, this paper provides a case study of the
launch of the Starlink constellation to further highlight the need for EIA
pertaining to in-orbit activities. While the obligation of performing an EIA
for space activities is not likely to become customary international law, it is
a resource that states can, and should, implement to achieve the sustainability
of space activities.