Keynote Speaker with Q&A - Karen Howard (U.S. GAO’s Acting Chief Scientist) to discuss their report on Large Constellations of Satellites, Mitigating Environmental and Other Effects .

Dr. Howard is GAO’s Acting Chief Scientist and the Director of Science and Technology Assessment. In these roles she leads teams of scientists, engineers, and policy analysts to provide insight, oversight, and foresight for the U.S. Congress through analysis of science and technology issues and the related policy implications. She manages a broad portfolio of topics including environmental quality, vaccine development, biological threats, chemical weapons, water scarcity, artificial intelligence, national security implications of emerging technologies, and many other issues.

Dr. Howard received the prestigious 2021 Arthur S. Flemming Award for Leadership in Government Service, GAO’s 2022 Distinguished Service Award and 2019 Meritorious Service Award, and others. She holds a PhD in Environmental Chemistry, MS in Analytical Chemistry, and MS in Education.

The emerging phenomenon of large satellite constellations is rapidly changing both low-Earth orbit (LEO) and the night sky. The deployment of thousands of satellites in the coming years stands to irrevocably alter the appearance of the night sky worldwide, and unlike in the case of conventional ""ground based"" light pollution, the changes to the sky will be visible even in locations far from urban centers (Lawler et al, 2021).

While software and other mitigation techniques may reduce the severity of satellite impacts on professional astronomy, such tools will not erase the changes to the night sky that will remain visible to the naked eye in real time. This is problematic for a variety of people who engage with the night sky, such as amateur astronomers, astrophotographers, recreational stargazers, and Indigenous peoples (Venkatesan et al, 2021).

Broader awareness of satellite constellations' effects on the night sky for communities beyond professional astronomy is slowly increasing: these issues have been mentioned in recent papers and have been discussed the media (eg. Venketesan et al., 2020; Noon, 2022). Efforts to better understand diverse perspectives on these issues and to converse with more communities include the SATCON2 Community Engagement Working group in 2021 and the creation of the Community Engagement Hub of IAU'S CPS in 2022.

However, though there has been increasing dialogue and meaningful discussions between professional astronomers and satellite operators regarding possible mitigations of some satellite impacts on research astronomy, there have been few avenues for other communities with concerns about the constellations to voice their views or participate in the decision-making processes that are resulting in marked changes to the night sky.

This talk will begin with a brief review of the recent history of "Community Engagement" as it has existed as a part of American Astronomical Society (AAS) and IAU CPS initiatives. It will then discuss the current "state of the field" in regards to what is known about satellite constellation impacts on the wider community of people who engage with the night sky, and it will go on to describe current activities taking place in relation to "Community Engagement" in this space. It will conclude by identifying areas where further work is needed in order to better address issues related to equity and inclusion regarding the future of the night sky.

Lawler, S. M., Boley, A., & Rein, H. (2021). Visibility Predictions for Near-Future Satellite Megaconstellations: Latitudes near 50 Degrees will Experience the Worst Light Pollution. Astronomical Journal, 163, 21. https://doi.org/10.3847/1538-3881/ac341b

Noon, K., (2022, April 19). Thousands of satellites are threatening ancient Indigenous astronomy practices. The Conversation. https://theconversation.com/thousands-of-satellites-are-polluting-australian-skies-and-threatening-ancient-indigenous-astronomy-practices-173840

Venkatesan, A., Lowenthal, J., Prem, P., & Vidaurri, M. (2020). The impact of satellite constellations on space as an ancestral global commons. Nature Astronomy, 4(11), 1043–1048. https://doi.org/10.1038/s41550-020-01238-3

Venkatesan, A., et al. (2021). SATCON2 Community Engagement Working Group Report. https://ui.adsabs.harvard.edu/abs/2021zndo...5608920V/abstract

My project is an ongoing investigation of the multiple, concurrent conflicts arising from the emergence of low-earth-orbit (LEO) satellite constellations with a focus on Starlink, owned by SpaceX. Earlier satellites’ high operating altitudes, operational costs, and slow internet speeds generally limited satellite internet use in favour of well established terrestrial broadband networks. Now, a new generation of LEO constellation operators argue they are capable of overcoming existing infrastructural barriers to provide reliable broadband internet worldwide.

Such claims are not new. They are part of an ongoing discourse where infrastructures have long been seen by many commentators as capable of annihilating time and space by facilitating seamless flows of information, goods, and people. The telegraph, railways, and the internet, all subject to the hyperbole delineating a new era. These infrastructures would render one’s physical location irrelevant, yet entail widespread and often detrimental changes to multiple environments. Moreover, the establishment of these networks were premised on linking more centralized, urban regions at the expense of rural communities marginalizing them.

LEO constellations like Starlink differ as the places on the edges of existing infrastructural networks, rural and remote communities, are SpaceX’s primary targets for market expansion and integration. Likewise, LEO is seen as a means to avoid the large-scale damages and changes made to environments with earlier terrestrial infrastructures. However, LEO constellations engender new, overlapping conflicts concerning the viability of LEO internet connectivity, the future of astronomical research, and how outer space will be framed in future environmental legislation. Here, my interest lies in how actors navigate and contest claims of ubiquitous, physically unbound connectivity provided by LEO constellations and how this infrastructure sees discursive and legal reimaginings of what constitutes nature.

This presentation will engage with the themes of community engagement and awareness raising, through proposing narratives which provide alternative stories to the belief in unrestricted technological development. The plan to launch up to 400,000 satellites into Earth orbit is an example of unregulated corporate capitalism: many private corporations and governments are encouraging rapid growth of the space sector without sufficient consideration of broader consequences for Earth and space environments or the interests and welfare of the wider community. We are facing an act of environmental pollution of a similar kind to the pollution of the air by coal smoke in the twentieth century, the pollution of the oceans, and now the wider food chain, by plastics and micro-plastics, or the deforestation of the Amazon.

The critique of the implications of the mass launch of potentially hundreds of thousands of satellites should take notice of the principles of communicating science to a wider public (Besley). There are now a wealth of studies dealing with the use of ‘story’ to communicate science (Dahlstrom; Downs; Jones and Crow; Muindi et al). Max Weber’s theory of value rationality provides a model for narratives used to secure support for the original US space race in the 1960s (Campion) and this presentation suggests that public awareness of the risks of the proposed satellite launches can be reinforced by narratives drawn from the sustainability arena.
Concepts such as ecocide can be applied to the notion that pristine space is being destroyed. Deep ecology tells us that near space is actually not so far away; rather, it is part of our extended Earth environment. Environmental ethics provides frameworks for arguing that nobody has the right to destroy a collective environment. Heritage studies reinforce our right to see a dark sky as much as we have the right to see a mountain, a river, or the ocean. Health studies raise the question of the interference of light pollution on wellbeing.
This talk will delve into ways in which narratives of sustainability can be used to engage a wider community in discussions to find solutions that prioritize the long-term sustainability of the Earth and Space environments.

References
Besley, John C., and Anthony Dudo, Strategic Science Communication: A Guide to Setting the Right Objectives for More Effective Public Engagement (Baltimore, Johns Hopkins University Press, 2022).

Campion, Nicholas, ‘Introduction: Discoursing with the Heavens’ in Nicholas Campion (ed.), Heavenly Discourses, (Lampeter: Sophia Centre Press, 2016), pp. xiv-xxviii,

Dahlstrom, Michael F., ‘Using narratives and storytelling to communicate science with nonexpert audiences’, Proceedings of the National Academy of Science, 111 (Supplement 4), 13614-13620, September 15, 2014, https://doi.org/10.1073/pnas.1320645111

Muindi, Fanuel J., Lakshmi Ramachandran, Jessica W. Tsai, ‘Human Narratives in Science: The Power of Storytelling’, Trends in Molecular Medicine, Volume 26, Issue 3, March 2020, pp. 249-251. https://doi.org/10.1016/j.molmed.2019.12.001

Downs, Julie S., ‘Prescriptive scientific narratives for communicating usable science’, Proceedings of the National Academy of Science, 111 (supplement_4) 13627-13633, September 15, 2014, https://doi.org/10.1073/pnas.1317502111

Jones, Michael D., Crow, Deserai Anderson, ‘How can we use the “science of stories” to produce persuasive scientific stories?’, Palgrave Commun, 3, 53 (2017). https://doi.org/10.1057/s41599-017-0047-7

Muindi, Fanuel J., Lakshmi Ramachandran, Jessica W. Tsai, ‘Human Narratives in Science: The Power of Storytelling’, Trends in Molecular Medicine, Volume 26, Issue 3, March 2020, pp. 249-251. https://doi.org/10.1016/j.molmed.2019.12.001

The Steward Observatory LEO Satellite Photometric Survey is a comprehensive observational survey to characterize the apparent brightness of the Starlink and OneWeb low Earth orbit satellites and evaluate the potential impact on astronomy. We report the results of over 16,000 independent measurements of nearly 2,800 individual satellites.

The apparent brightness of a satellite seen in the sky is not constant and depends on the Sun-satellite-observer geometry. To capture this, we designed the survey to create an all-geometries set of measurements to fully characterize the brightness of each population of satellites as seen in the sky. We visualize the data with sky-plots which show the correlation of apparent brightness with on-sky position and relative Sun-satellite-observer geometry. The sky-plots show where in the sky the satellites are brightest. In addition to visual magnitudes, we present a new metric: the expected photon flux. The expected photon flux metric assesses the potential impact on astronomy sensors by predicting the flux for a satellite trail in an image from a theoretical 1 meter class telescope and sensor.

We intend to use this methodology and resulting data to inform the astronomy community about satellite brightness. Observing programs use a variety of telescopes and instruments and look at different parts of the sky. With the expected photon flux metric and a complete all-sky characterization of satellite brightness, observers can evaluate the potential impacts to their projects and possibly avoid the worst effects.

Each panelist will give a 5 minute introduction, followed by Q&A.

David Vincent Stark (Space Telescope Science Institute)
At the Space Telescope Science Institute, I have led the development of a new software package to identify and mask satellite trails in astronomical imaging data. Our approach is based around a modified version of the Radon Transform (which we call the Median Radon Transform). The key advantage of this method is its sensitivity; it can detect linear features with mean brightness significantly below the background noise level of an image, and it is resistant to false detections caused by bright astronomical sources (e.g., stars, galaxies) in the majority of cases. The software has been incorporated into the “acstools” Python package that is publicly available. We applied this technique to 30,000 images taken between 2002 and mid-2022 using the Wide-Field-Channel (WFC) on the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope (HST). We find that the rate of satellite trails in ACS/WFC imaging data has increased by approximately a factor of two in the last two decades, with approximately 10% of images currently affected, but there is no clear systematic evolution in the typical trail brightness.

Genoveva Micheva (Leibniz-Institute for Astrophysics)
It's infeasible to prevent satellites from intersecting the field of view (FoV) of 4MOST, especially given the survey program's extended exposure durations. On average, each satellite that traverses the 4MOST FoV will affect approximately 1.3 fibers. While many of these satellite trails will be too dim to impact the 4MOST spectra significantly, some will be bright enough to subtly but imperceptibly alter the data. Without a mitigation, this issue would make it impossible to rely on individual 4MOST spectra; only large statistical samples could be analyzed. This would also hinder the exploration of anomalous spectra for groundbreaking scientific discoveries. Our simulations with 4MOST indicate that satellite contamination can subtly affect stellar metrics like radial velocity and elemental abundances, depending on the satellite's brightness level. These effects are so subtle that they evade detection by our existing data processing and quality control pipelines. To address this, 4MOST plans to employ a specialized imager for real-time, continuous FoV monitoring to identify crossing satellites. However, the technical specifications for this imager present challenges that have yet to be resolved.

Samuel T. Spencer (Friedrich-Alexander Universität Erlangen-Nürnberg)
I am a co-author on a recent study considering the effect of satellite constellations on H.E.S.S. observations. H.E.S.S. is an Imaging Atmospheric Cherenkov Telescope (IACT) array located in Namibia, and is designed to perform ground-based gamma-ray astronomical observations. It works by detecting the optical to near-UV Cherenkov light emitted when gamma-ray photons interact with Earth’s atmosphere and initiate an Extensive Air Shower (EAS) (or particle cascade). Unlike optical or radio astronomy, we infer the presence of very-high-energy gamma-rays by classifying and determining the properties of these EAS events. The effect of satellite trails on these IACT observations has previously been considered minimal, due to their approximately 10 nanosecond signal integration time. However, IACTs are still exposed to the night sky and sensitive to optical frequency light, and therefore could potentially be affected by satellites. It was important to quantify this, given the continuing satellite launches, and the construction of the next-generation Cherenkov Telescope Array (CTA) observatory. This has already begun on La Palma with the inauguration of the Large Sized Telescope 1 (LST-1) telescope (which you’ll visit tomorrow). A second site for CTA will be located in Chile, near Cerro Paranal. In our study we developed a method of detecting satellites in H.E.S.S. data using night sky monitoring measurements, which H.E.S.S. cameras take concurrently with gamma-ray observations. We showed that, whilst measurable, the effect of satellite trails on EAS event classification and reconstruction with H.E.S.S. is minimal. Nevertheless, we observe a mildly increasing trend in the number of trails detected over the past three years. However, new analysis techniques that aim to reduce the energy threshold of IACT observations with next generation instruments could be more severely affected.

Zouhair Benkhaldoun (Oukaimeden Observatory, Cadi Ayyad University)
The Oukaimeden observatory is a partner of the IAU-CPS center and as such, the observatory's researchers are involved in the satellite observation part. Through the deployment of a variety of professional and amateur telescopes, the observatory provides satellite observation services. It presently contains a variety of initiatives as well as dozens of telescopes that participate in daily satellite observation. The observatory also provides facilities for accommodating and collaborating with other satellite observation programs, as well as an academic and professional training program to support observational activities. Furthermore, utilizing orbital data processing techniques, the observatory has developed a variety of unique platforms that aid in observation planning. These user-friendly methods enable more effective observation scheduling, thereby increasing the observatory's contribution in the various scientific objectives behind satellite observations. We propose to present in this contribution, the progress made by the Observatory team with the facilities offered to all observatories around the world to contribute to the observation and data analysis program relating to this important aspect in the objectives set out by the IAU-CPS centre.

Benjamin Winkel (MPIfR)
Large satellite constellations can have an impact on modern radio astronomy in various ways. Classically compatibility studies have focused on the wanted transmissions and their by-products (e.g. spectral side-lobes) in the bands allocated to the satellite radio services and adjacent. Recently, however, other interference vectors have emerged, such as electromagnetic leakage from onboard electronics. Also, satellite constellation owners team up with terrestrial cell-phone network operators to smoothly integrate both systems. Needless to say that this provides extra challenges as the carefully constructed coordination scheme between cell phone networks and the affected radio services does not include space-based infrastructure. The basis for all regulation activities related to the above are compatibility studies. As large constellations can consist of thousands of satellites, full network simulations are required. These have to consider the dynamic behavior of transmitters and receiver, antenna patterns (including side-lobes and time-variable pointing), aggregation effects and - at higher frequencies - atmospheric effects. The International Telecommunication Union has developed procedures and algorithms that can assist such calculations. Nevertheless, the implementation is highly non-trivial, especially with respect to computational costs.

The threat from satellite constellations to astronomical observations in the visible and near infrared bands has been quantified by simulations and observations. Mitigation strategies are being developed at all levels from satellite design to observation strategies and data processing algorithms. This is particularly the case for imaging and especially wide-field imaging, the most affected type of observation with glaring trails zapping through the images in the most dramatic way.

Spectroscopic data also deserve careful consideration: they represent a large fraction of all the observations, and spectrographs face a different challenge. Indeed, they lack most or all spatial information that could reveal a tell-tale satellite trail, thwarting attempts to detect the contamination of the spectrum. Furthermore, because of their fast apparent motion, the satellites cross the slit (or fiber, or resolution element) in an extremely brief time of the order of a millisecond. Accounting for their apparent magnitudes, the contamination will typically be at a level comparable to that of the science target. This will make the detection and mitigation of the contamination difficult, potentially resulting in incorrect scientific interpretations.

We will present realistic examples of contaminations, highlighting the difficulty of detecting them. We will also discuss the challenges of forecasting and flagging these stealth contaminations. The computed position of a satellite must have a precision of about 1 arcsec to be useful for spectroscopy, which is difficult. Alternatively, a camera monitoring the field-of-view can detect an incoming satellite, provided the images can be analyzed in real time.

The CHaracterising ExOPlanet Satellite (CHEOPS) is a partnership between the European Space Agency (ESA) and Switzerland. It is the first S-class mission in the ESA Science Programme. CHEOPS has been flying on a Sun-synchronous low Earth orbit since December 2019, collecting millions of short-exposure science images in the visible domain to study exoplanet properties.

A small yet increasing fraction of CHEOPS images show linear streaks caused by satellites and orbital debris crossing the field of view. CHEOPS’ orbit is indeed particularly favorable to serendipitously detect objects in its vicinity as the spacecraft rarely enters the Earth’s shadow, sits at an altitude of 700 km where most artificial objects orbit, and observes within 60 degrees of the anti-Sun direction. Objects crossing the field of view are therefore illuminated nearly all the time with small phase angles relative to the Sun making them as bright as they can get. This observing configuration is quite powerful for space surveillance and it is complementary to optical observations from the ground.

In order to characterise the population of satellites and orbital debris observed by CHEOPS, all and every science images acquired over the past 3 years have been scanned with a Hough transform algorithm to identify the characteristic linear features that these objects cause on the images. Thousands of streaks have been detected. This statistically significant sample shows interesting trends and features such as an increased occurrence rate over the past years as well as the fingerprint of the Starlink constellation. The cross-matching of individual streaks with cataloged objects allows us to reconstruct the observational circumstances which are required to deduce the apparent magnitude of the detected objects.

As space agencies and private companies are preparing space-based surveillance and tracking activities to catalog and characterise the distribution of small debris, the CHEOPS experience is timely and relevant. Besides, developing a synergy between actors of the space sector and the astronomical community would benefit all parties for our future endeavours.

Our contribution will present the status of our analysis, including operational aspects, detection and identification processes, as well as some quantitative and statistically robust results.

CHEOPS has recently been granted a mission extension until the end of 2026 the earliest. This will enrich our sample of orbital debris and extend the time coverage of recurring object crossings, making this dataset even more valuable to the community.

The propagation of Laser Guide Stars (LGS) for Adaptive Optics (AO) correction is impacted by satellites for those telescopes which are required to follow the US DoD Laser Deconfliction Protocol. The number of closure windows, when lasers are not permitted to propagate, has increased since the first LEO Satellite Constellations were launched and, if left unchecked, will put the US-ELTs at a serious scientific disadvantage compared to the non-US community.

We will present an overview of US Department of Defense Laser Deconfliction Protocol and how it affects laser propagation and will discuss the impact of the Satellite Constellations and the various mitigation measures which we are exploring with various Federal Agencies and the Satellite Constellation companies.

The presentation will provide a detailed walk through of the design, construction, and operation of a DIY monitoring station, emphasizing its affordability, accessibility, and ease of use. The station leverages readily available components, including Software Defined Radio (SDR) receivers and a Raspberry Pi 4. These tools allow for constant 24/7 monitoring and automatic storage of band usage and the detection of Doppler shifts in the satellite beacons, providing valuable data for analysis.

Preliminary analysis using this DIY setup can indications of power levels and beam shapes of the Starlink satellites and use strategy. Additionally, an experimental interferometer mode has been implemented, further expanding the capabilities of this home-based monitoring station with direct positional information.

The UK’s Federation of Astronomical Societies (FAS) has a membership of almost 200 amateur astronomical societies and indirectly represents about 12,000 individual amateur astronomers. The societies’ latitudes range approximately between 50°N and 57½°N with the median at about 52°N (halfway between London and Birmingham).

About 70% of the current Starlink satellites have an orbital inclination of 53° and spend about 9% of their time north of latitude 50°N. 53°N is greater than the latitude of nearly 75% of the FAS’ member societies so there is potentially a large number of amateur astronomers affected by Starlink trails.

This paper presents the results of a survey of the members of the FAS’ member societies to determine the extent of interference they have experienced from satellite trails, the trend in that interference, any mitigation methods they have used, the effectiveness of those methods, their awareness of satellite data that might help them plan their observations and their general awareness of the potential problems that will arise from satellite constellations in future.

The Pampilhosa da Serra Space Observatory (PASO) is located in the center of the continental Portuguese territory, in the heart of a certified Dark Sky destination by the Starlight Foundation (Aldeias do Xisto). As part of the Portuguese Space Surveillance & Tracking (SST) network, PASO hosts the rAdio TeLescope pAmpilhosa Serra (ATLAS) currently in test phase, and a double Wide Field of View Telescope system (4.3° x 2.3°) . These instruments complete an already installed deployable optical sensor for MEO and GEO surveillance. The tracking radar will track space debris in Low Earth Orbit (LEO) up to 1000 km and at the same time the telescope will also have LEO tracking capabilities offering additional spectroscopy capabilities enabling light curve analysis.

The number of space activities, including the launch of constellations of satellites and the associated space debris population, has been steadily increasing, raising concerns over the impact on the sky quality for astronomical purposes. Near-future data fusion concepts using space radar and very wide-field tracking telescopes for Space Surveillance and Tracking (SST), such as the PASO telescopes (Coelho et al. 022), will provide additional information that is much needed to accurately model the orbital parameters and attitudes of satellites and debris.

This article intends to discuss possible ways to take advantage of having these two sensors at the same location. Using both types of sensors take advantage of the radar measurements which give precise radial velocity and distance to the objects, while the telescope gives better sky coordinates measurements. With the installation of radar and optical sensors, PASO can extend observation time of space mega constellations and space debris and correlate information from optical and radar provenances in real time. During twilight periods both sensors can be used simultaneously to rapidly compute new TLEs for LEO objects, eliminating the time delays involved in data exchange between sites in a large SST network. This concept will not replace the need for a SST network with sensors in multiple locations around the globe, but will provide a more complete set of measurements from a given object passage, and therefore increase the added value for initial orbit determination, or monitoring of reentry campaigns of a given location. PASO will contribute to the development of new solutions to better characterize the objects improving the overall SST capabilities and constitute a perfect site for the development and testing of new radar and optical data fusion algorithms and techniques for constellations and space debris monitoring.

The increasing number of space debris and mega-constellations is becoming a serious problem for terrestrial astronomy. Light trails caused by these objects contaminate astronomical images, rendering them ultimately worthless. Knowing where in the sky and how bright these objects will be is essential to optimizing observation planning and avoiding such contamination. Photometric phase functions are a powerful tool for understanding asteroids and resident space objects (RSOs) such as satellites, upper stages, and space debris. However, they also provide a means of predicting how these objects will reflect light toward the observer. For our analysis, we chose the model proposed by Hejduk (2011), which assumes a spherical object with diffuse and specular components. Using more than one million photometric measurements of more than 10,000 objects from the Mini-MegaTORTORA (MMT) light curve catalog, we were able to define the phase functions of more than 600 rotating RSOs. We have also defined the phase functions for the mega-constellation satellites, namely Starlink and OneWeb, which are operational and controlled.

In addition, we have created an online space debris forecasting service for professional and amateur astronomers as well as astrophotography enthusiasts. Thanks to this service, the user can define a planned line of sights to observe during the observation night and at a specific time. This student project’s service will provide a list of objects that theoretically contaminate FITS frames. It is built on the long-term software solution SatEph, which has been used by Comenius University for more than a decade to observe space debris. It is a fast, accurate and reliable algorithm built on the well-known simplified general perturbations model SGP4.

In our work, we will discuss in detail the photometric properties of space debris and satellites extracted from the MMT photometric catalog using the Hejduk model. Physical parameters of selected populations, such as geometric albedo and beta parameter, which are necessary for accurate brightness predictions, will be presented. Introduced will be our freely available online service that predicts brightness of RSOs, including space debris and mega-constellations, during astronomical observations to support astronomers' decision making.

In more than 60 years of space activities, more than 6050 launches have resulted in about 15760 satellites placed into Earth Orbit, of which about 8100 are still functioning. They are regularly tracked by surveillance and tracking systems. All the experience gathered on building up and maintaining such a catalogue could bring valuable inputs that would benefit ground and space-based sensors devoted to astronomy to mitigate large satellite constellations impact on their scientific goals.

ESA is funding activities to facilitate coordination among heterogeneous sensors distributed worldwide (within the Space Safety program) like the Space Safety Expert Centre hosted and operated at AIUB university in Bern (Switzerland). This system provides services as well to validate and qualify passive optical sensors and laser ranging sensors, to ensure that they are compatible with space debris and satellite observation accuracy needs to build and maintain a catalogue of objects.

Research on different types of observations techniques, software tools to model and predict the attitude evolution as well as brightness variation of a satellite and tools to detect satellite streaks in images are some examples of activities currently under development by ESA. Both are available under ESA Community License and can support the modelling and mitigation of effects of satellite trails on astronomical images.

The presentation will cover the most commonly used observation techniques and lessons learnt from sensors devoted to satellite catalogue maintenance. Highlights of some helpful software tools to predict the attitude evolution of a satellite and streak detections in images will be presented.

The deployment of mega-constellations in recent years has exponentially accelerated the number of Resident Space Objects (RSOs) in Earth orbit, significantly increasing the threat of collision between RSOs (active satellites and debris). The US military and European Space Agency both possess large networks of infrastructure to detect and classify RSOs for the purposes of defence and surveillance, with some of these results available publicly. These networks are comprised mainly of optical and radar-based systems which can perform Space Situational Awareness (SSA) in real time - a necessity for collision prevention warnings.

Due to the unintentional detection of RSOs and aircraft in SKA-precursor radio band datasets, a new approach to SSA is being developed. Passive bi-static radar - meaning that the transmitter and receiver are spatially separated and not coordinated - has been proven to perform SSA tasks. Reflections of FM band radio frequency transmission off RSOs has been detected over 1,000 km, as well as direct transmissions from some RSOs out to Geostationary orbits at 36,000 km. Our efforts have primarily concentrated on performing a comprehensive analysis across multiple frequencies at the SKA-Low site to identify and characterise significant signals. This presentation will delve into the intriguing signals that we have successfully detected.

Satellite constellations frequently perform manoeuvres to maintain the operational orbital configuration or to avoid collisions against debris or another operational spacecraft. Predictions based on surveillance data typically does not contain this manoeuvre information. Hence, manoeuvres must be shared and coordinated with other spacecraft operators to allow predicting future conjunctions. This data exchange and conjunction prediction process is comparable to the pass prediction problem of the astronomical community, where spacecraft are not appearing at the expected location on the sky due to the performed manoeuvres. Data is shared between operators directly or via online platforms. ESA is funding research and development activities, e.g., within the Space Safety programme, to develop coordination platforms that allows related bilateral negotiation between operators to facilitate exchange and safe operations.

Additionally, ESA is developing tools that allow analysing the compliance of missions with regards to space debris mitigation requirements and guidelines. Among other capabilities, the process and software can be used to estimate the lifetime in orbit (until re-entry), collision avoidance efforts (e.g. expected amount of manoeuvres for a mission and fuel requirements), and on-ground casualty risk estimation (e.g. in case of uncontrolled re-entry). In the future, the software will be extended with basic functionality to calculate the brightness and radar cross section (RCS) of satellites for an approximate initial estimation of the trackability and light pollution during the satellite design phase. Efforts are under way to further develop guidelines and policies so that future satellites must support tracking by surveillance systems to allow for better orbit determination and collision avoidance operations. Hardware solutions such as artificially increasing the RCS or visors to reduce the brightness are being investigated as well.

The presentation will explain the typical space debris mitigation aspects in the spacecraft design process, and the data sharing products in operations, their applications and lessons learned from the collision avoidance domain. Outcomes from completed and running activities for operator coordination and space debris mitigation including ESA’s zero debris approach are highlighted.

The IAU Centre for the Protection of the Dark and Quiet Sky (CPS), Policy Hub has established Work Packages for addressing multiple challenges associated with orbital light and spectrum pollution. We present a preliminary report by the Work Package 2 (WP2) team that analyzes (1) law and policy frameworks that pertain to the use and exploration of outer space, (2) what those frameworks mean for a range of space sustainability issues, and (3) how those frameworks may be changing. Building on the work of Dark and Quiet Skies II, the analysis considers international and national contexts, and seeks to synthesize how different national laws, policies, and initiatives, along with obligations and commitments to international law and guidelines, create responsibilities of states to reduce light and spectrum pollution that result from their space activities. Other environmental impacts are also considered.

The report further analyzes, separately and as part of the overall synthesis, the inclusion of obligations toward Indigenous Peoples’ rights and interests, while recognizing that there is no single Indigenous identity.

The report is careful to recognize that states have interests in supporting both satellite development and astronomical observations, and that both activities bring large benefits to humanity in many ways.

The WP2 report is intended to be a driving document for action within the IAU CPS, as well as a reference for other entities that are exploring the governance of outer space activities and their impacts. Thus, the intent is for the report to enable subsequent “operational” documents that focus on specific issues highlighted in the report and promote constructive discussions within national and international fora.

The report identifies a series of key questions concerning humanity’s use and exploration of space, answers the questions where possible, and where not possible, describes some of the elements that cause uncertainty or a diversity of opinions among the WP2 members. Answers are given by looking at the questions through international, national, Indigenist lenses. This is followed by a discussion that analyzes the interconnectivity between these views. The report concludes with recommendations to the CPS on actionable steps for promoting the meaningful incorporation of dark and quiet sky protections into national and international legal and policy frameworks.

The CPS Policy Hub, Working Package 2 (WP2), International Law team, is conducting an extensive research project aimed at broadening the understanding of international law's role in protecting dark and quiet skies, as well as identifying ongoing policy trends resulting from current changes in the use and exploration of outer space. This presentation provides an overview of the international frameworks section of the WP2 report, elucidating key findings and addressing a series of guiding questions that navigate the complex landscape of international law in this realm.

The report acknowledges the advantages of astronomical observations and satellites to humanity, advancing ways of gathering information and sharing knowledge, including science, shaping economic opportunities, fostering cooperation, and providing fundamental infrastructure. The report also recognizes that astronomical observations, particularly astronomy, and satellites both require resource exploitation. This exploitation of resources can have positive or negative impacts on communities, including Indigenous peoples.

The report provides an overview of the international discussion regarding the nature of astronomical observation as a form of space activity, both conceptually and legally. It reviews various scholarly interpretations of international law that support the classification of astronomy as the use and exploration of outer space while acknowledging that this view might not be universally recognized. It also considers whether identifying astronomical observation as a space activity is a prerequisite to protecting dark and quiet skies or whether alternate avenues of protection could be feasible.

Moreover, the report dissects provisions of space law, such as the principles of 'due regard' and 'harmful interference.' It reflects on the current practices and controversies surrounding satellite constellation registration and brings attention to liability issues related to the potential harm caused by space activities.

The report then analyses international governance mechanisms pertinent to dark and quiet sky protection, including human rights considerations, explores the responsibilities and mandates of international bodies like the UNOOSA and the ITU, discusses the relevance of existing comparable frameworks, and examines space as an environment and the applicability of international and national environmental law.

By questioning these essential aspects of international law, the presentation aims to highlight the WP2 work that is exploring a comprehensive and nuanced understanding of the international frameworks that govern the use and exploration of outer space. The report ends with recommendations to the CPS on actionable steps that the IAU can take to foster the preservation of dark and quiet skies.

During the last several years, dark sky protection has received increasing attention at different political and regulatory levels. This has been prompted by the proliferation of artificial light at night (ALAN) and the number of mega-constellation satellites being placed into low-earth orbit (LEO). These changes have created a complex set of concerns, ranging from impacts on astronomical activities to environmental protection, and can no longer be ignored by national governments.

This presentation will introduce preliminary research results conducted by the IAU CPS Policy Hub, Work Package 2, National Analysis team. It identifies policy and legal approaches to the protection of dark and quiet skies for astronomical observations in various jurisdictions across the globe. The presentation summarises the key findings in the report, which include, inter alia, main measures to address light pollution and the associated regulatory trends. It also will discuss known obstacles to addressing the growth of light pollution.

Previously conducted research, such as that in the Dark and Quiet Skies II report, has shown that several countries have adopted legislation to preserve the sky for astronomical activities. Building upon that work, the current report provides a detailed synthesis of the adopted policies and legislation in a broader range of countries. The research addresses the three main questions: (1) whether a given country has an existing framework for protecting dark and quiet skies for astronomy; (2) whether light pollution is recognized as a problem at the national level, and (3) whether there are any relevant regulatory frameworks applicable to address the concerned issue. This approach enables an understanding of national action towards light pollution mitigation and the identification of potential regulatory improvements in the dark sky protection field.

In addition, this report sheds light on other aspects of the national protection of dark skies for astronomical activities, e.g., recognition of astronomy as a space activity, licencing procedure of large constellations, incorporation of international law concepts into national legislation and beyond.

Altogether, the presentation brings a broader understanding of legal and policy challenges that can be faced by the astronomical community in different countries and provides recommendations on how these obstacles could be overcome in the future in order to preserve dark and quiet skies.

Acknowledging that space is a common good, and a multistakeholder spectrum, free for use and exploration to equally benefit the entirety of mankind, and specifically in consideration of the numerous benefits that a multidisciplinary and holistic approach to the protection and preservation of the dark and quiet skies can provide, the National Analysis group was formed, as a part of Work Package 2, the IAU CPS Policy Hub, to highlight the importance of due consideration of the national frameworks of various space-faring nations.

This presentation will explain the preliminary research results of the national analysis of the dark and quiet skies regulations in Slovenia, Slovakia, Poland, Egypt, United Arab Emirates, Sri Lanka, Viet Nam, and India. Each country’s legislation and policy will be thoroughly analyzed to provide a concise summary including the answers to the following questions: 1) Does a particular state have a dark and quiet skies protection framework or initiatives, relevant to astronomical activities; 2) Is light pollution recognized as an issue in domestic legislation, and 3) Are there any other related and relevant regulatory frameworks or initiatives applicable to address the issues in question.

In the identification of policy and legal approaches to the protection of dark and quiet skies, this presentation is to provide further detail, by focusing on adopted instruments, such as particular laws, policies, and initiatives (planned, in procedure, or in place), as well as specific measures to address light pollution for conduction of astronomical activities and observations.

In addition to the main research questions, this presentation will further clarify the subject by answering the subsequent questions: (1) does access to a dark and quiet sky fall under the mandate of a single or multiple national regulating bodies? (2) does the particular state define what constitutes harmful interference?; (3) is light pollution a form of pollution under national laws?; (4) is the supervision of national activities required during the entire mission?; (5) what is this state's definition of damage, if any, and is it in line with the Liability Convention definition?; (6) how does the particular state treat the authorization and registration of large constellations?

Conclusively, the main goal of this research is to raise awareness on the issue of light pollution and the importance of protecting the dark and quiet skies, in order to preserve outer space for future astronomical activities. Additionally, this research is to gather relevant data on the current status, the progress or the lack thereof, of any and all developments and initiatives in particular national jurisdictions. By doing so, current trends, potential developments and progress will be noted, as well as legal lacunae or inconsistencies, which should facilitate in indicating the ways forward.

The tranquility of our night sky is under an unprecedented threat, with light pollution rapidly increasing and the imminent proliferation of satellite constellations. The consequences of these issues extend far beyond astronomy, affecting climate, wildlife, and communities. However, the urgency to address them has yet to translate into unified action. It is crucial to recognize that the impact on the night sky is not solely an issue for astronomers but a concern for all living beings.

DarkSky aims to establish a global coalition dedicated to preserving our precious dark and quiet skies. This initiative seeks to unite stakeholders worldwide, including marginalized communities, in developing a shared vision and actionable roadmap. Through collaboration, awareness-raising, and advocacy for policy changes, we aspire to protect our celestial wonders and promote sustainable practices.

During our conference presentation, we will review our proposal and seek input from participants. We highly value the expertise and insights of conference attendees, recognizing that aligning our efforts will amplify the impact of the global coalition. We invite open discussion on collaborative strategies, potential partnerships, and innovative approaches to tackle the challenges posed by light pollution and satellite proliferation.

The envisioned outcomes include establishing a robust global coalition committed to preserving dark and quiet skies, integrating light pollution and satellite proliferation concerns into organizational policies, and empowering dark sky advocates to drive policy reforms. A comprehensive report, available in multiple languages, will serve as a roadmap for action and a catalyst for securing funding and support.

Let us unite behind the cause of protecting our vanishing skies. By bringing together diverse stakeholders and harnessing collective wisdom, we can ensure the enduring existence of dark and quiet skies, mitigate the impacts of light pollution, and cultivate a harmonious coexistence between humans, wildlife, and our shared natural environment. Your valuable input and collaboration are integral to our shared success.

In 2022, the total number of active satellites orbiting the earth is averaging 10,000. It is foreseen that by the end of the decade, additional tens of thousands of satellites are going to be launched. In addition to the many challenges related to spaceflight safety in an increasingly congested environment, there is growing concern among the astronomy community regarding the impact of such a densely populated sky on observations. There are presently no binding requirements or guidelines at international level to mitigate the impact of satellites on astronomical observations. In a similar manner as in the field of SSA, cooperation between stakeholders (astronomers and satellite operators) is needed in order to understand the impacts, identify solutions or mitigation actions, and implement them.

In that context, tools such as the Space Sustainability Rating (SSR), a rating system designed to assess the sustainability of space missions, can play a role in fostering responsible behaviour in order to mitigate the impact of satellites on astronomy. While the SSR is already operating in its first version, it was foreseen that its methodology would be updated incrementally. The goal of the research presented in this work is to define the rationale, methodology, and expected outcomes of developing a “Dark and Quiet Skies” module for the Space Sustainability Rating.

The Dark and Quiet Skies module intends to quantify the impact of space missions on the astronomical observations, and output a score between zero and one, that will then contribute to the final SSR score. The module will be split into two sub components, addressing the impacts on both optical and radio astronomy. As other modules of the space sustainability rating, the Dark and Quiet Skies module will (i) assess the impact of a given mission that can be composed of one or several spacecrafts, and (ii) account for efforts from operators to mitigate their impact through design or operation of their satellites.

The Dark Skies (optical) component is derived from the detectability framework of the SSR, and aims at quantifying the apparent and effective magnitudes of spacecraft composing a mission. The impact of a mission in terms of data loss for a given set of telescopes will be studied in this work. Whereas the aggregated impact of a mission shall be quantified, the goal of the SSR is also to incentivize every mission to implement best-practices. In that regard, a rating methodology to rate missions at spacecraft and mission (fleet) level will be proposed in this work. The Quiet Skies (radio) component follows a similar approach, in quantifying the level of harmful radio-frequency interference of a mission, and considering solutions that can be implemented to mitigate the impact at spacecraft and fleet level. At this stage, the Quiet Skies sub-component is a qualitative questionnaire allowing to gauge the level of compliance with existing best-practises to limit radio frequency interference.

In this work, a brief state-of-the art of the impacts of satellites on astronomical observation will be presented, followed by the current module development status, as well as the next steps towards the module finalisation.

In 2022, Dark Sky International (then International Dark-Sky Association) and policy advocate Amy C. Oliver launched a grassroots policy campaign in the United States for International Dark Sky Week that sought proclamations (ceremonial documents, declarations) from U.S. local and state governments offering their support and acknowledgement of the week's efforts to educate the public and stakeholders on dark skies protection and threats. This netted 23 proclamations and 16 media stories. In 2023, the pairing, along with policy intern Michael Rymer, launched a more ambitious effort with the Dark Sky International advocate network, which so far has resulted in 94 proclamations issued, with 19 coming from other countries and one from a tribal nation, and 867 media stories around the world. This project emphasizes three key areas in dark skies preservation: (1) Creating leverage for gaining media attention with a non-official document issued by a government entity; (2) Creating tools and resources for public education and broadening outreach via media interactions; (3) Creating “soft opens” with government and policy stakeholders for discussions on implementable policy.

This presentation explains the role of proclamations/ceremonial documents/acknowledgments as a soft opening to creating permanent change in policy. These documents, while not implementable policy, provide a soft and positively charged opening for difficult conversations on what is becoming ever more complex policy. We break down how to write and request a proclamation, leverage it with the media and broader public, and then use its issuance to start and/or bolster important policy conversations.

While this project was aimed at broader dark skies outreach, its applicability to the ongoing and growing conversation about satellites and their impact on astronomy and dark skies as a whole cannot be overlooked. Grassroots policy projects have the power to engender positive support from policymakers as they create permanent infrastructure within broad communities so that smaller internal communities, like the astronomy community, can execute stronger collective action. This presentation additionally will target key ways in which already issued proclamations for dark skies can be used for conversations with the public, policymakers, and stakeholders in the conversation about satellites, and how and when additional similar documents may be issued as we work towards global consensus.

The Moon is a unique site for a variety of astronomical observations enabled by the rare characteristics of individual sites. For example, the farside of the Moon is shielded from radio interference by radio sources on Earth and in Earth’s orbits. Being a radio quiet environment, it represents the perfect location to perform low frequency radio observations that could lead to the detection of the very faint atomic hydrogen signal belonging to the “Dark Ages”. This is of extraordinary importance for cosmology and fundamental physics research. However, science experiments require extremely sensitive instrumentation so that electronic\noise leakage from other sources could severely limit the scientific value of the farside. Meanwhile, the presence of water and minerals on the Moon has attracted commercial attention and enlarged the number of players interested in outer space raw materials. The lunar sites with extraordinary scientific importance (SESIs) often overlap with those that have the most concentrated valuable resources. Their extraction requires intense mining activities with harmful impact on the neighboring environment.

Good astronomical sites are rare, no matter where they are located, so protecting the very special ones on the Moon is an appropriate scope for the IAU, as it requires international policy. The IAU could make common cause with other scientific organizations and even take a leading position to urge the UN COPUOS, through the IAU’s observer status, to activate a process for the protection of SESIs.

In order to make the European communication infrastructure more resilient and to strengthen the technological sovereignty in space, the European Parliament and the European Council decided in November 2022 to build a new satellite constellation: IRIS2-Infrastructure for Resilience, Interconnectivity and Security by Satellite.

The constellation will be realised through several hundred satellites in multiple orbits and is intended to ensure secure and very fast connectivity for commercial and institutional channels even in places where terrestrial broadband is not feasible or economical.

The constellation must also meet the EU's "Green Deal" requirements (avoiding an increase in space debris, protection of other services), use the latest technologies and optimally protect communications against cyber-attacks by applying quantum encryption.

As a member of the DG DEFIS expert group, I would like to give a deeper insight into the constellation's architecture, regulations and challenges.

The UK is an ambitious space nation, and at the same time aspires to be a ‘science superpower’, with a strong astronomical community, embodied in membership of ESA, ESO and SKAO (with its headquarters in Cheshire). Despite Brexit, that scientific community retains an enduring commitment to international collaboration.

Unusually, as a result of a decision made during the height of the Covid pandemic, the UK government is also a part owner of OneWeb, so has a special responsibility for space sustainability, including the impact of large satellite constellations on astronomy.

Since 2019 the Royal Astronomical Society has attempted to lead work brokering engagement between astronomers and our government on satellite constellations, while grappling with political turbulence (three prime ministers and alternating science minsters in a single year), vested interests and a complicated regulatory structure.

In this paper I will give an overview of our progress so far, including tangible successes like the establishment of the Earth Space Sustainability Institute (with support from King Charles III), support for Dark and Quiet Skies at UN COPUOS, and the recent G7 declaration. On the other hand, astronomers have far less influence than leading space companies, and it remains to be seen whether protection of our science will lead to a licencing regime with teeth. Fundamentally, one part of the public budget continues to be invested in astronomy, and another in spacecraft that put some of this science at risk.

Public and political awareness of the impact of satellite constellations is also apparently still low, despite work with media outlets, MPs and members of the House of Lords, and a number of high profile public events.

The challenge in the UK has parallels in other nations. I would like to share the lessons from our approach to date, how we hope to make our contribution to the global effort to protect our sky in the years ahead and to seek feedback and input that can shape our plans.

The purpose of this session will be to provide updates on the current state of satellite constellation plans and deployments, the latest analysis on their impact on astronomy, recent mitigation techniques and tools, and the next steps underway as constellation deployments continue.

Four and a half years ago, the first deployment of SpaceX’s Starlink satellites took the astronomy community by surprise with their brightness. This prompted concerns that large numbers of satellites could affect scientific discoveries and kicked off an unusual collaboration between satellite constellation operators and astronomers.

Since 2019, thousands of commercial satellites have been launched into with more than 500,000 satellites have been proposed by companies and governments from around the world. The constellation craze is being propelled by problems on Earth like climate change and broadband connectivity that can be addressed by space-based solutions from low-Earth orbit (LEO). New investments into large-scale space projects, innovations in spacecraft manufacturing, and eased access to space from cheaper launch are fueling the constellation trend, with evermore proposals and some market exits.

Constellations have demonstrated economic, social and strategic benefits, but have also raised questions about their impact on the space environment, their ability to share scarce radio spectrum, to operate safely with each other and to coexist with optical and radio astronomy. Substantial industry effort has gone into the novel tech area of reflection, with thousands of satellites deployed with modifications just to safeguard astronomy. Industry and astronomers are pairing to track and observe LEO satellites and new tools are emerging to predict and mitigate the effect on astronomy.

So if satellite constellations are here to stay, what have we learned about their effects on ground-based optical and radio astronomy? What new solutions have emerged to mitigate their effects and which should satellite constellation operators be considering? And how is this new intersection between two valuable space endeavors landing in the space sustainability and space policy context? An expert panel discuss the unexpected intersection of two space communities and their work toward coexistence.

Moderator: Tim Stevenson, SKAO and Co-Chair of the I&T Hub - introduce the current state of play and discuss work of I&T Hub to raise awareness and advance mitigations

Constellation Backdrop: Patricia Cooper, President, Constellation Advisory LLC – overview of current constellations and drivers

Mitigation Update: Dr. David Goldstein, SpaceX Director of Special Programs – SpaceX mitigation efforts, current mirrors and efficacy

Audience Questions & Answers: Moderated by Tim Stevenson

The Earth & Space Sustainability Initiative is a UK Space Agency-funded project to bring together industry, academia, governments, international organisations, and the finance and insurance communities to ensure that space continues to support the environmental, economic and scientific interests of current and future generations. It is developing the Space Sustainability Principles that will facilitate the establishment of the Space Sustainability Standards. In this presentation, I will outline ESSI's approach and how you can get involved.

Dr Stuart Clark runs Expanded Universe Ltd, a communications consultancy and content creation agency specially geared towards the space and high-tech physics sectors. His background is in infrared astronomy, and he remains a Visiting Fellow at the University of Hertfordshire. He has worked in science communications for most of his career, working for ESA, New Scientist, BBC Radio 3 & 4, The Guardian. He is the Director of Communications for ESSI.

To tell the story of the need to protect our near-space environment, I have travelled to the top of volcanoes in the Pacific and Atlantic Oceans, clean rooms across Europe, mega-constellation launches on both coasts of the United States, and a farm in England. I also went on a journey through the space sector: government, space agencies, military, regulation, insurance markets, academia, astronomy, and space sustainability enterprises. Through a series of reportage photographs and portraiture, I have documented the benefits of using space, the cost to the near-space environment, and the beginnings of our stewardship.

For most of human history, space has been a remote realm, unreachable and mysterious. Earlier generations filled it with their various hopes, dreams and fears. Then in 1957, things changed. The former Soviet Union launched Sputnik 1, and we began filling space with actual pieces of hardware.

We have now transformed the orbital space around Earth into a technological bridgehead. In the process, we have proven the societal and scientific benefits of using this environment. With the tumbling cost of satellites and launches, more and more companies are thinking of how to use space. No longer can we consider it ‘outer space’. It has become ‘near space’, part of the Earth’s environment, inextricably linked to our way of life and the functioning of society. Instead of a frontier to be tamed, the near-space environment is one over which we must now exercise stewardship. As the problem of space debris increases, along with the sky becoming progressively crowded and light polluted, our new role is to ensure that space is used sustainably. This means guaranteeing the benefits remain available to future generations and also to preserve the night sky for humanity.

Through visual storytelling, I take a human perspective, from the ground looking up, so the public and interested parties can become aware of what is happening just up there, and make more informed decisions.

This presentation will lay out a plan for engaging the International Court of Justice on the issue of interference to astronomical observations caused by satellite mega-constellations.

Astronomers have engaged at length with SpaceX and other satellite companies. Some progress had been made, but the amount of interference continues to grow. Where mitigation efforts have taken place, they have so far been temporary, insufficient, and not part of the fundamental design process. With record numbers of satellites being launched, substantial degradation of ground-based astronomy is a serious concern.

Astronomers have sought to inform and influence the decisions of national regulatory agencies, notably the US Federal Communications Commission. They have provided input to US domestic courts when FCC orders have been appealed. They have engaged with the media in an effort to inform the general public and thereby influence political decision-makers. None of these efforts has delivered the desired results or wide recognition of the problem.

In 2022, a proposal was submitted to the UN Committee on Peaceful Uses of Outer Space for a new expert group, which would report to COPUOS’s Scientific and Technical Subcommittee. The expert group would monitor the impact of satellites on astronomy, seek inputs from global stakeholders, and make recommendations for mitigations. The proposal was championed by Chile, Spain, Slovakia, Bulgaria, the Dominican Republic, Peru, and South Africa, as well as the European Southern Observatory, International Astronomical Union, and Square Kilometer Array Observatory. While it was discussed at length at the June 2023 meeting of COPUOS, the proposal was ultimately not adopted. COPUOS operates on the basis of consensus, and consensus does not exist on this issue.

The international legal system includes many courts and tribunals. The most prominent of these is the International Court of Justice, one of the six principal organs of the United Nations. The ICJ can only adjudicate disputes between states, but in this instance, that limitation is not a problem. Article VI of the Outer Space Treaty stipulates that ‘States Parties to the Treaty shall bear international responsibility for national activities in outer space … whether such activities are carried on by governmental agencies or by non-governmental entities.’ All satellite companies are incorporated in states, and their satellites are licenced by national governments.

The easiest way to engage the ICJ is through a request for an ‘advisory opinion’. An advisory opinion is legal advice provided to the United Nations or a specialized UN agency by the International Court of Justice, in accordance with Article 96 of the UN Charter. To date, the ICJ has provided 27 advisory opin¬ions on matters that range from the conditions of a state’s membership in the UN to the legality of the threat or use of nuclear weapons. Seventeen of these came at the request of the General Assembly.

Although advisory opinions are not directly binding on states, they still carry weight as reasoned, authoritative assessments of the law by the most respected international court or tribunal, and therefore also carry considerable moral authority. They are also an excellent way of drawing diplomatic, media, public and political attention to an issue.

Requests for advisory opinions by the UN General Assembly are adopted as resolutions of that 193 member-state body. Importantly, the General Assembly does not operate on consensus basis: All that is required is a simple majority of the UN member states present and voting. For the purpose of determining which states are ‘pres¬ent and voting,’ abstentions do not count as votes. Thus, requests for advisory opinions do not require support by a majority of UN member states; they simply require more votes in favor than against.

Following a favorable vote by General Assembly, the request for an advisory opinion is communicated to the ICJ in written form, containing an exact statement of the question(s) the Court is being asked to address.

A draft resolution can be proposed by just one state, though a group of states is more desirable. The states that championed the proposal for a new expert group at COPUOS are the logical ones to take the lead here: Chile, Spain, Slovakia, Bulgaria, the Dominican Republic, Peru, and South Africa. The backing of major international astronomical organizations would also be helpful. Again, the organizations that supported the proposal for a new expert group at COPUOS are the logical ones to take the lead: European Southern Observatory, International Astronomical Union, and Square Kilometer Array Observatory.

With this approach, an authoritative assessment regarding the impacts of mega-constellation satellites on astronomical observations can be determined quickly, with major ramifications for states’ international obligations, and is not a process that can be stopped by any single state.

Surprisingly large numbers of post-mission satellites will be decaying towards re-entry at any time, after the mega-constellations are highly populated and one mission lifetime has expired. This presentation shows calculations that there will be many thousands at one time. And these post-mission satellites will have substantial additional issues for astronomers.

Closely based on the presentation to the UK Space Agency’s Dark and Quiet Skies conference in January, with Prof Martin Barstow in our wrap-up session ‘The Future of Dark and Quiet Skies’, and a related presentation in May to the AIAA annual conference in Irvine, CA, this presentation will aim to answer these questions: How many active Internet satellites would be in orbit when all the projected Internet constellations are fully populated? How many post-mission Internet satellites would be decaying downwards towards re-entry, at any given time? How will the size of these populations inform the expected Dark and Quiet Skies impacts? What are the special issues for astronomers from post-mission satellites? What is the best path forward for mitigation?

Mitigation methods to be considered will include larger satellites in each orbital ring, to service or de-orbit Internet satellites that have failed or run out of propellant, as well as joint research projects to develop and mature subsystems to deploy drag balloons or drag tethers. Discussion will include the potential for a joint research facility at an appropriate existing space research center.