Editorial
Guest Editorial: As Above, So Below—and Closer Than They Appear
by Howard V. Hendrix
This essay takes its title from a line in my long-ago second novel, Standing Wave. Here and now and many years later, I find that phrase a lot less mystical or metaphysical than it seemed to be when I first used it. This is especially the case in the context of meaningful analogies and parallels that can be drawn today between population growth in satellite numbers in the heavens above, and population growth in human numbers on the Earth below.
I. Kessler’s Satellite Population Bomb
There are five “official” layers of Earth’s atmosphere. The lowest layer, the troposphere, ranges up to about seven miles (11 km) above sea level, or to about a mile higher than Mount Everest. The next layer up, the stratosphere, ranges from about 7 miles to about 31 miles (50 km) up. Commercial passenger jets fly at the lower reaches of this atmospheric layer. The next layer above that, the mesosphere, ranges from 31 miles to about 50 miles (80 km) above the Earth and is where most meteors burn away as shooting stars.
The next layer above that, the thermosphere, ranges from about 50 miles to an average of about 440 miles (710 km) up. It has been home to auroras, space shuttles, and the International Space Station. In the thermosphere’s lower reaches one finds the Karman line, the traditional boundary between Earth’s atmosphere and outer space, about 62 miles or 100 km up. (The top of the thermosphere is an average number because the thermosphere’s height varies strongly with changes in the amount of solar energy impacting it.)
The last layer, the exosphere, is home to most of the artificial satellites orbiting Earth. The exosphere starts just above where the thermosphere ends. Where the exosphere—the last layer of our atmosphere’s gaseous envelope—itself ends is up for grabs, with estimates ranging from 62,000 miles (100,000 km) to 120,000 miles (190,000 km) above the Earth.
Orbits of artificial satellites overlap these layers: Low Earth Orbit (LEO), the most common home to satellites, covers from about 96 miles up (160 km) to 1200 miles (2000 km) above us, thus also straddling the thermosphere and the exosphere. Medium Earth Orbit (MEO) is solidly within the exosphere but is bookended between LEO’s 1200-mile top height and Geostationary Equatorial Orbit (GEO) at 22,233 miles (35,780 km) above the Earth. Satellites in GEO are sometimes said to be in a Clarke orbit or Clarke belt, after Arthur C. Clarke, the scientist and science fiction writer who, in the February 1945 issue of Wireless World magazine, first described and popularized the special properties of geostationary orbit.
Space may be “big,” as the saying goes, but usable orbital space is by no means an inexhaustible commodity. Clarke’s work helped open up what has since become “wild, wild space,” a zone where a satellite gold-rush mentality currently reigns, something Clarke might never have imagined. In contrast to that recent satellite-bonanza mindset among billionaires, Donald Kessler’s work—beginning with “Collision Frequency of Artificial Satellites: The Creation of a Debris Belt” (1978) and especially in “Collisional Cascading: The Limits of Population Growth in Low Earth Orbit” (1991)—reminds us how foolhardy it is to allow the orbital space frontier to be too open and/or too unruly.
The self-propagating character of the “Kessler syndrome” involves chain reactions among colliding objects in space, leading to more space debris and more colliding objects, on and on, potentially preventing future generations from accessing and utilizing space. This trajectory of use reminds us that orbits are “resource units” in that grand commons for global civilization, the orbital space around Earth.
Like other grand commons, orbital space also has a resource-specific carrying capacity. As a species, our record with other grand commons and with issues of overall sustainability has not been good. Consider plastic and microplastic trash nearly everywhere (but especially in the oceans) and CO2 pollution in the atmosphere. As I write this, too, human resource demand this year will use up 1.8 times the Earth’s capacity for biological regeneration of ecological resources. All of these data points are solid analogs for what is happening now with debris in space.
Yet, in the near term, Elon Musk’s Starlink—the number one source both of LEO satellites and of potential collision hazards in Earth orbit—has been given the go-ahead or is completing the paperwork for lofting into LEO at least 42,000 broadband internet communication satellites (ranging in size from dining tables to pickup trucks, arrayed in “mega-constellations”) by 2033. OneWeb, Rocket Lab, Amazon’s Project Kuiper, Virgin-Orbit and other billionaire-backed space companies have go-aheads for many thousands more satellites, whose radio signals and glint-clutter “trains” pose increasingly serious problems for radio astronomers and optical astronomers, respectively.
Astronomers already see how the night sky is being degraded by space junk—especially due to what’s going on in LEO. And all of the recent increased privatization of space with its associated orbital debris doesn’t even take into account civil governmental projects such as China’s proposed megaconstellation Guowang, numbering 12,992 satellites. Also inadequately dealt with on the near frontier is the nature of the debris that has already been generated by earlier nation-state military actions, particularly antisatellite weapons tests by the USA, Russia, China, and India.
Terms like “go-ahead” and “paperwork” suggest the satellite-lofting process is more regulated and constrained than it actually is. Most national and international satellite proposals are readily approved via a patchwork of agencies that license launches. These agencies coordinate with international bodies regarding specific satellites, orbits, and slots in the global radio frequency spectrum. All of this “regulation” too is almost exclusively on the front end: There is no binding international treaty covering the cleanup of human-made space debris. As the song “Wernher von Braun” by Tom Lehrer puts it, “Once the rockets are up, who cares where they come down?” Or what they might collide with while in orbit. . .
Ranging in size from paint flecks to defunct multi-ton satellites, the millions of pieces of satellite debris that have accumulated over nearly seven spacefaring decades are not just sitting or tranquilly floating out there in some cosmic junkyard. Those pieces of debris are moving at velocities between 7 and 15 times as fast as a speeding bullet. They form what I have called a Kessler ballistosphere, an ever-thickening human-created layer or shell of hyperbullet junk whipping around the Earth, making orbits evermore crowded and evermore likely to be the scene of recurring debris smashups.
The ongoing increases in ballistospheric density threaten to undercut the ability of satellites to keep doing all the many things they already do for us, including communications, navigation, and weather and climate-change monitoring, not to mention the services they might provide in the future. Yet laws governing this near frontier are weak and poorly enforced. There is no national or international sheriff—nor even a posse deputized by binding agreement—capable of bringing desperately needed order to the high frontier. Hall thrusters, Whipple shielding, passive infrared sensors, onboard AI—none of these technological fixes will solve the problems presented by the growing ballistosphere so long as we keep space-jamming low Earth orbits with more and more satellites and post-mission debris.
In the worst-case scenario resulting from collisional cascading, the ballistosphere becomes so unnavigable as to constitute a de facto “final” frontier, preventing future journeys to the Moon or Mars or anywhere else. Paradoxically too, the advent of reusable rockets and cheaper production costs for satellites—the very conditions that have made possible the space bonanza now underway—may well result in the collapse of that same space-rush, and sooner than we might expect.
Profitability space is more constrained than usability space. When ballistic debris-strikes start taking out half of the new satellites being lofted, new satellite launches will rapidly become economically infeasible. Even if the door to the sky never shuts completely, the boom will still go bust if we do not take steps to prevent it.
II. Amara’s Law and Ehrich’s Human Population Bomb
This may sound to some like Chicken Little’s squawking that “The sky is falling!” or “The Boy Who Cried ‘Wolf’!” crying, well, wolf. Nonetheless, catastrophic events do occur. In his book The Precipice, philosopher Toby Ord estimates that the chances of humanity encountering an existential catastrophe during the next 100 years from all natural causes combined (asteroid or cometary impact, supervolcanic eruption, natural climate change, stellar explosion, natural pandemic, and the like) is approximately 1 in 10,000. The chances of our species encountering an existential catastrophe as a result of human causes, though—nuclear war, anthropogenic climate change, overpopulation, biodiversity crash, engineered pandemics, biowarfare, uncontrollable nanotechnology, general artificial intelligence not aligned with “human values”—the risk of these human-caused existential disasters Ord puts at 1 in 6 during the next 100 years. Humanity, it appears, has most to fear from humanity itself.
Human responses to potential boom-busts, however, are a bit more complicated than these odds suggest. Whether we are talking about populations of satellites or populations of humans, we are essentially dealing with the impacts of technological change. It took 300,000 years for Homo sapiens numbers to reach one billion (around 1803, although global human numbers began slowly but steadily increasing in the sixteenth century). For many tens of thousands of years, technological advancements in the human toolkit incrementally increased Earth’s carrying capacity for human beings. However, technological innovations in sanitation, medicine, and agriculture, among other activities, have over the last few centuries resulted in a spectacular spiking of population and expansion of Earth’s “apparent” (as opposed to real) carrying capacity for humans.
Because technological change is so crucial to growth in satellite population and in human population, we have some grounds for describing both of them in terms of Amara’s Law: “We tend to overestimate the effect of a technology in the short run and underestimate the effect in the long run.” The initial overestimation can be negative or positive: Apocalypse to Pollyanna, “the sky is falling” to “the sky’s no limit.” The underestimation phase, however, transforms Chicken Little into the shepherd boy who cried wolf. Chicken Little is wrong to be paranoid about sky collapse, but the shepherd boy turns out to be more on-target—his false alarms and hype being more accurate—than he could have guessed. The wolf is coming down on the fold, even if no one at last wants to hear its howling.
Growth in satellite population in LEO and in human population on Earth follow the same innovation-driven expansion dynamic. In each, growth was slow before particular sets of technological innovations co-occurred—again, in sanitation, medicine, and agriculture for human population; in satellite miniaturization and mass production, mega-constellations, and reusable rockets, for satellite population. After their respective innovation co-occurrences, the populations of the local heavens and the Earth exploded exponentially, raising questions about the sustained carrying capacity for humans on Earth and for satellites in orbit.
Kessler’s descriptions and predictions for satellite population growth and Paul Ehrlich’s descriptions and predictions for human population growth were often dismissed, initially, as premature overreactions to that growth. It is true that Ehrlich (particularly in The Population Bomb) overestimated human population growth and underestimated the power of the Green Revolution to expand food production. Kessler, in raising the specter of the shutdown sky, has at times been seen as overestimating the effects of satellite population growth and underestimating cultural and technological responses to that growth. Both Ehrlich’s and Kessler’s earlier predictions may be seen as products of the overestimation phase in Amara’s Law—as can the responses themselves, in this context. Or it may be something simpler: “First they ignore you. Then they ridicule you. And then they attack you and want to burn you. And then they build monuments to you,” as trade union activist Nicholas Klein said in a speech from 1918.
Today, in the underestimation phase, time is proving both Ehrlich and Kessler right about population and carrying capacity in their respective domains of human and satellite space. Neither of them was just shouting that the sky is falling. The Green Revolution has turned out to be not so green, and the response to the Satellite Rush not so stellar. In both cases benefits have been overestimated in the short term and risks underestimated in the long term. Regulatory frameworks, concerned with the consequences of growth both in the satellite population space and in the human population space, lag woefully far behind that growth itself.
Since innovation and invention are creatures of human imagination, and human imagination purportedly has no limits, we have long assumed that we can always innovate our way out of any self-created predicament. On the contrary: If we cannot imagine a limit to human imagination, then it is self-evident that human imagination has limits—and that innovation and invention also must.
The potential dangers presented by the wolf of human overpopulation and the sky-
fall of satellite overpopulation are real. If we hope to bend the trajectory of human history away from boom-bust and toward a more sustainable and survivable future, we continue to ignore such “as above, so below” parallel dangers at our peril. Waiting until the nick of time may be too late, especially if those dangers turn out to be closer than they appear.