On November 18, 2019, around 19 Starlink satellites crossed over Cerro Tololo Inter-American Observatory, significantly disrupting astronomical research and affecting ongoing scientific work. (CLARAE MARTÍNEZ-VÁZQUEZ / CTIO)

The relationship between business practices and regulations has always been clear: if no laws exist to prevent an action, one is free to pursue it. In the absence of rules safeguarding resources, individuals or companies often exploit them for personal gain. Until regulatory frameworks are established, innovators frequently self-govern, often to the detriment of those relying on increasingly scarce resources.

In the realm of astronomy, the most crucial resource is a dark, unobstructed night sky—humanity's gateway to the cosmos. Traditionally, challenges to this resource have included atmospheric turbulence, cloud cover, and light pollution. Recently, however, a new form of interference has emerged, posing a serious threat to astronomy: large constellations of satellites. If the trajectory of Elon Musk's Starlink initiative continues unchecked, it could spell the end of ground-based astronomy as we currently understand it.

A SpaceX Falcon 9 rocket launched from Cape Canaveral Air Force Station, deploying 60 Starlink satellites on November 11, 2019. The planned Starlink constellation aims to include thousands of satellites for global high-speed internet, but the detrimental impact on astronomical science is already considerable and likely to increase in the future. (Paul Hennessy/NurPhoto via Getty Images)

The deployment of satellites to enhance services for those on Earth has become essential in our modern lives. Satellites for GPS and telecommunications underpin our mobile connectivity today. With the advent of 5G, new infrastructure will be necessary, which in turn requires launching an upgraded fleet of satellites.

SpaceX, led by Elon Musk, is among the pioneers in this field, proposing an initial deployment of 12,000 satellites as part of the Starlink mega-constellation, with aspirations to eventually expand to 42,000. As of November 20, 2019, only 122 of these satellites had been launched, yet they have already significantly impacted astronomy worldwide.

To counteract this trend, either regulatory bodies or SpaceX executives must take decisive action.

From the darkest locations on Earth, approximately 9,000 stars can be seen by the naked eye, reaching a visual magnitude of +6.5. However, the initial 122 Starlink satellites are not only brighter than most of these stars, but they also traverse the sky swiftly, creating trails that contaminate astronomical data.

If the satellites were dim, limited in number, or moved slowly, the issue would be less severe. Astronomers could simply disregard exposure frames where these objects appeared. However, the large number of bright, fast-moving satellites complicates matters, especially for observatories designed to detect minute changes from frame to frame.

On November 18, 2019, 19 Starlink satellites crossed the observing frame of the Dark Energy Camera at the Cerro Tololo Inter-American Observatory, lasting over five minutes. This event severely impacted the DECam instrument, which captures images over a field of 3 square degrees at a remarkable resolution of 0.263 arcseconds per pixel.

This incident, though representing only 0.3% of the total planned Starlink satellites, illustrates the serious consequences for wide-field astronomy, particularly for projects focused on detecting faint objects—key objectives for observatories like Pan-STARRS and LSST. Averaging over frames is not a viable solution, as it obscures the natural variability of celestial objects, an essential aspect of astronomical research. The autonomous orbit changes and high radio emissions from Starlink satellites further complicate efforts to schedule ground-based observations.

Low Earth orbit is already crowded with thousands of human-made objects, with 95% categorized as “space junk.” Each dot in this illustration signifies either an operational satellite, an inactive one, or debris. While collisions are rare, the addition of thousands more satellites could not only pollute the night sky but also complicate the space surrounding Earth for years to come. (NASA ILLUSTRATION COURTESY ORBITAL DEBRIS PROGRAM OFFICE)

Unlike traditional low-Earth satellites that gradually decay and return to Earth over months or years, Starlink satellites are positioned at altitudes exceeding 1,000 km, where they could remain for millennia. In September, the ESA’s Aeolus satellite, which conducts Earth observations, had to execute an emergency maneuver to evade a potential collision with a Starlink satellite, despite it being SpaceX's responsibility to adjust its orbit.

SpaceX and Musk have made claims stating that:

• The satellites will minimally affect astronomy.
• SpaceX will work to reduce satellite reflectivity.
• Starlink will facilitate on-demand orientation adjustments for scientific studies.

As of November 20, 2019, however, none of these assertions have been realized.

Previous satellite networks, like the Iridium constellation, were successful due to their predictable orbits and limited numbers (66 satellites), which only flared brightly under specific conditions. In contrast, Starlink and similar networks, such as Kuiper Systems and OneWeb, present unprecedented challenges for ground-based astronomy.

Cees Bassa from the Netherlands Institute for Radio Astronomy notes that at any given time, up to 140 such satellites could be visible from any observatory on Earth. However, if the companies behind these constellations implement a few straightforward measures, these challenges can be effectively addressed. Here are some recommendations for responsible stewardship of the night sky, and how SpaceX can mitigate the damage currently inflicted on astronomy.

1. De-orbit the existing Starlink satellites and impose a halt on new launches until necessary modifications are made. The current Starlink satellites are large and reflective, already causing astronomers to discard significant portions of their data. Currently stationed at 280 km, visible to the naked eye, they can be de-orbited safely. However, once elevated to their operational height of 550 km, they become a more permanent issue. Public awareness may diminish, but they will still be observable with binoculars and telescopes, vital tools for astronomers. Every moment these satellites remain in orbit is akin to willfully disregarding the needs of scientists and researchers, particularly those who rely on limited telescope time to advance their careers.
2. Redesign or coat the satellites to significantly reduce their reflectivity. The current Starlink satellites are not only large but highly reflective. These characteristics are choices that could be altered. By adopting different designs or applying a low-albedo coating, the adverse effects on astronomy could be minimized. Implementing sensible measures to decrease reflectivity could reduce their apparent brightness by approximately 100 times.
3. Provide real-time trajectory predictions and adjustments to observatories globally. One of the significant drawbacks of these satellites is their unpredictable paths. If their trajectories were known, astronomers could plan observations to minimize disruption to their work. Establishing a global network to track and continuously update the predicted paths of each satellite would enable astronomers to avoid polluted areas while maximizing their observations.
4. Allocate funding to support astronomers in developing solutions to mitigate satellite interference. Even if all recommended changes are implemented, astronomers will still face challenges in accounting for the residual contamination in their data. It is unreasonable to expect that Starlink or any satellite company will have no impact on astronomy, but it is entirely reasonable to demand financial support for astronomers to address these challenges.

This principle is standard practice across various industries: if a natural resource is exploited, restitution for the damage caused is required. The astronomers I know are not opposed to having satellites in orbit; they simply wish to continue their work despite their presence. This is not an unreasonable expectation.

By applying to the International Telecommunications Union for authorization to operate an additional 30,000 Starlink satellites (beyond the 12,000 already approved), the character of the night sky will be irrevocably altered. If Elon Musk, Starlink, SpaceX, and other key players in this domain are genuinely committed to being responsible custodians of the night sky, they should proactively address these issues without waiting for regulatory bodies to intervene.

Presently, the Outer Space Treaty only prohibits military use of space; all other peaceful applications are permitted. There are no consequences for damaging the night sky, nor are there regulations governing pollution or interference. As long as satellite operators register their devices and avoid collisions, they bear no legal liability for their actions.

The astronomical community faces a choice: push for laws that protect the night sky or hope for self-regulation within the industry. If companies like SpaceX, Kuiper Systems, and OneWeb choose to tackle these challenges proactively, they will emerge as responsible leaders in this burgeoning sector. However, it is disconcerting to consider that the future of one of humanity’s oldest sciences may hinge on the ethical considerations of a few profit-oriented firms. Our understanding of the Universe, from nearby hazardous objects to distant celestial phenomena, is no longer solely in the hands of astronomers.

Starts With A Bang is now on Forbes and republished on Medium with support from our Patreon contributors. Ethan has authored two books, *Beyond The Galaxy and Treknology: The Science of Star Trek from Tricorders to Warp Drive.