The case for space environmentalism

Abstract

The shell bound by the Karman line at a height of ~80-100km above the Earth's surface, and Geosynchronous Orbit, at ~36,000km, is defined as the orbital space surrounding the Earth. It is within this region, and especially in Low Earth Orbit (LEO), where environmental issues are becoming urgent because of the rapid growth of the anthropogenic space object population, including satellite 'mega-constellations'. In this Perspective, we summarise the case that the orbital space around the Earth should be considered an additional ecosystem, and so subject to the same care and concerns and the same broad regulations as, for example, the oceans and the atmosphere. We rely on the orbital space environment by looking through it as well as by working within it. Hence, we should consider damage to professional astronomy, public stargazing and the cultural importance of the sky, as well as the sustainability of commercial, civic and military activity in space. Damage to the orbital space environment has problematic features in common with other types of environmental issue. First, the observed and predicted damage is incremental and complex, with many contributors. Second, whether or not space is formally and legally seen as a global commons, the growing commercial exploitation of what may appear a 'free' resource is in fact externalising the true costs. MainThis article has its origin in an Amicus Brief [1] submitted to the US Court of Appeal in August 2021, in support of an appeal made by several organisations against a specific order made by the US Federal Communications Commission (FCC). That order granted license amendments for SpaceX Starlink satellites. As we write, the appeal process is still underway, but all submissions to the Court have been made, so it is appropriate to make the material public. Since constructing the Amicus Brief, similar very general environmental arguments have been made in an article by L. Miraux [2]. Orbital space and its regionsMost anthropogenic space activity is between altitudes of 100km to 36,000km. For the purposes of this article, we refer to this as "near Earth orbital space", traditionally classified in three broad regions.Low Earth Orbit (LEO) is generally understood to be at altitudes of 100 to 2,000km, with many anthropogenic space objects (ASOs) at around 500km. LEO has traditionally been dominated by scientific, earth observation and military missions, with some communications systems. The orbital period at these altitudes is around 90-120 minutes, and so, seen from Earth, any one satellite moves across the entire sky in a few minutes. Orbits in this region decay due to atmospheric drag, but the timescale varies significantly from a few months at the lowest altitudes to hundreds of years above ~1,200km.Medium Earth Orbit (MEO) is at altitudes around 20,000 km, within a broad range. This is the regime of global navigation satellite systems such as GPS and GLONASS, but also recently of some internet communications systems such as O3B. Satellites in MEO take around 12 hours to orb...

Satellite Constellation Avoidance with the Rubin Observatory Legacy Survey of Space and Time

“…We note that earlier publications (Tyson et al 2020;Lawrence et al 2022) stated that the majority of LSST images are likely to contain a satellite streak. They also included some higher-altitude Starlink orbits that are no longer planned.…”

“…For a thorough discussion of the scientific utility of residual light after masking satellite trails, see Hasan et al (2022). Over the past three years, many astronomers have raised concerns about the impact of the proliferation of commercial satellites on the LEO ecosystem and astronomical surveys (Tyson et al 2020;Lawrence et al 2022). In addition, astronomers have come together with satellite operators and other stakeholders to create recommendations and strategies to mitigate impacts to observational astronomy and beyond (Walker et al 2020a(Walker et al , 2020b(Walker et al , 2021Hall et al 2021).…”

LEO Mega Constellations: Review of Development, Impact, Surveillance, and Governance

“…Starlink satellites use lasers to communicate with each other, and satellites capable of exchanging information are adjacent in the same orbit and on adjacent orbital planes. Among the initially planned 12,000 satellites, approximately 4400 satellites operate in the Ka-band (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40) or Kuband (12)(13)(14)(15)(16)(17)(18), and the remaining satellites operate in the V-band (60-80 GHz) [9] (Table 1). The user terminal of Starlink adopts a phased-array antenna, and the nearest Starlink orbital plane can be aligned by the antenna aperture for the precise positioning of satellites for simple operation.…”

“…Faced with such challenges, SpaceX proposed the testing of a satellite coating [35] and designed to reduce the reflectivity of Starlink satellites. However, reducing the brightness of satellites only has a limited effect on ground-based optical observations and does not have a positive effect on groundbased radio observations [36]. Therefore, the International Astronomical Union (IAU) [34], American Astronomical Society (AAS) [37], and National Aeronautics and Space Administration (NASA) [38] have all expressed strong concerns regarding the impact of LEO mega constellations on astronomical observations.…”

DUG Insight: A software package for big-data analysis and visualisation, and its demonstration for passive radar space situational awareness using radio telescopes

“…This last category of signal is interesting, as the increasing population of RSOs is beginning to impact Earth-based astronomy (Gallozzi et al, 2020), to the point where papers such as Lawrence et al (2022) are drafted in an effort to deter courts from allowing the mass launches of satellites. The International Astronomical Union says it is "Deeply concerned about the increasing number of launched and planned satellite constellations in mainly low Earth orbits" and have formed the Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference 2 to address this issue.…”