By William Cerny, Fall 2019.
On May 25th, 2019, keen-eyed observers in the Northern Hemisphere witnessed a truly spectacular sight: dozens of bright, fuzzy objects, one after another, forming a dazzling ‘train’ in the night sky. Remaining visible for far longer than any passing meteor, each glimmered with brightness comparable to the North Star — placing them among the 50 brightest objects in the sky for a brief period of time. Unbeknownst to many at the time, this spectacle had no natural origin. It was the simultaneous orbital passage of more than 60 satellites!
Launched aboard a variant of their signature Falcon 9 rocket, this collection of satellites constituted the second test launch for SpaceX’s fledgling Starlink, a self-described initiative to provide “low latency, broadband internet… to meet the needs of consumers across the globe… including those in rural communities and places where existing services are too expensive or unreliable.” To achieve this goal, SpaceX intends to launch up to 42,000 new miniature satellites into Low Earth Orbit (LEO) to form an interconnected network capable of providing consistent internet coverage to any location on Earth.[2] Matching SpaceX’s ambitions are a multitude of comparably young competitors; from Amazon’s Project Kuiper to the Softbank-backed OneWeb project, wealthy investors have clearly signaled their eagerness to capitalize on these initiatives to bring what is estimated to be half of the world’s population online.
These efforts, however ambitious, may come with serious consequences for human spaceflight and scientific research. Today, there are approximately 1,338 operational satellites in LEO — a number that could potentially increase by a factor of 100 should new constellations like Starlink reach their ultimate projections.[1] As this number of LEO satellites exponentially increases, orbital overcrowding quickly becomes a significant issue, and satellite collision becomes a very real possibility. Such a collision could have drastic influences on the human exploration of space because micro-debris in LEO travelling at high orbital velocities can easily puncture solid metal on space telescopes, other satellites, and larger-scale structures such as the International Space Station. To make matters worse, these micro-debris collisions can cause even more collisions, leading to a disastrous cascade of debris formation that could render LEO entirely unusable – a process known as Kessler Syndrome.
An equally important concern about these satellites arises from the fact that they can interfere with ground-based astronomy as satellites by darting through the field of view of ground-based telescopes. While the alarming sight of the SpaceX Starlink launch may have recently revitalized this controversy, these Starlink satellites are far from the first manmade objects to be visible to telescopes on the ground, or even to the naked eye. The International Space Station, for example, is particularly easy to track from the ground, as its short orbital period and large, reflective solar panels provide for visible transits across the sky every day. Also notable are the 82 satellites that form the existing Iridium satellite constellation, originally manufactured by the Motorola corporation to provide satellite phone and data coverage throughout the world.[3] Early models of these satellites had the unintended consequence of producing infamous “Iridium flares,” so-named for their extremely bright, transient flashes of light caused by the serendipitous alignment of their reflective surface areas with respect to the Sun. Fortunately, later models of these satellites replaced the original reflective material (notably, for non-scientific reasons), and many of the earlier Iridium satellites have fallen from orbit as a result of orbital drag, upon which they are summarily burnt due to friction with the Earth’s atmosphere. While SpaceX has affirmed their commitment to reducing Starlink satellites’ stark visibility from Earth by painting future satellites black, thereby reducing their apparent reflectiveness tenfold, many prominent astronomical institutions and governing bodies remain wary of the rapid development of satellite constellations. For example, the International Astronomical Union, one of the world’s foremost guiding authorities for astronomy, duly notes in their official statement regarding the Starlink launch that such constellations could pose a “significant or debilitating threat to important existing and future astronomical infrastructure”.[4]
In more specific terms, the IAU deems the threat from satellite constellations to be two-fold. Firstly, long exposure photography from wide field-of-view ground-based telescopes remains prone to inadvertently imaging these passing objects — a problem that certainly scales with the number of satellites in a constellation. Given immense recent investment from research institutions around the globe toward the construction of new large wide-field survey telescopes, protecting ground-based astronomy from deleterious passages of satellites remains a top priority for astronomers. Secondly, the IAU notes that these satellites also pose a challenge for observations at longer wavelengths, especially radio, where normal communications between satellites and ground-based receiver stations can interfere with scientific observations by radio dishes on Earth.[4]
Arbitrating these distinct astronomical interests with the corporate desire to profit off satellite internet systems will inevitably prove challenging. However, it certainly remains possible if immediate action is taken. Under the current regulatory framework, these companies need only gain Federal Communications Commission (FCC) approval for their launches, allowing for the expedient circumvention of scientifically-motivated concerns. In the past, the FCC has taken basic steps to protect scientific interests, including placing restrictions on wavelengths used for science (for example, on radio wavelengths which are used to map interstellar gas). Recently, however, regulation on the satellite constellation industry has been comparatively lacking: SpaceX has already received unilateral approval for 12,000 planned Starlink satellites, with no required congressional hearings or mandatory mediation with scientific representatives. In order to foster a mutually beneficial relationship, wherein space remains a frontier of both exploration and technological progress, significant structural changes to the existing legal system must be made. While the exact nature of these changes will remain a significant topic of debate for the coming decades, the most immediate action is clear: qualified, scientific experts’ voices must be considered, and common-sense regulations must be put in place that balances both corporate and scientific interests.
[1] Space.com. “Wow! This Is What SpaceX’s Starlink Satellites Look Like in the Night Sky.” All About Space. Last modified May 25, 2019. https://www.space.com/spacex-starlink-satellites-spotted-night-sky-video.html
[2] SpaceX. “Starlink.” SpaceX Starlink. Last modified November 11, 2019. www.starlink.com
[3] Wikimedia Foundation. “Iridium satellite constellation.” Wikipedia. Last modified October 29, 2019. https://en.wikipedia.org/wiki/Iridium_satellite_constellation
[4] Walker, C, 2019. “IAU Statement on Satellite Constellations.” International Astronomical Union. Last modified June 3, 2019. www.iau.org/news/announcements/detail/ann19035/