The following is an excerpt of  Dr. Space Junk vs The Universe by Alice Gorman. You can hear her interview here. 

We talk blithely of space junk but in fact, the concept of junk is a cultural one, which is not the same everywhere. We don’t get annoyed at people from the past for leaving their stone tools scattered about and not cleaning up after themselves—junk is more acceptable when it’s framed as archaeology.

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The contemporary era is different, though. It’s characterized by mass manufacture and consumption, with astronomical quantities of single-use objects ending up in landfill. Materials like plastics, which don’t decay quickly, or which have toxic by-products, have replaced the organics and low-level industrial products of the past. There’s more stuff than there ever used to be: more coffee cups, plastic bags, chocolate wrappers, cigarette butts, and paper clips.

Junk is defined not only as stuff that is abandoned, and of little value, but in contrast to nature. This is where the concept of litter adds another dimension. Litter means rubbish that has been disposed of in an inappropriate place, particularly in an urban public space but also parks, rivers, beaches and “wildernesses” where the footprint of human activities is (usually incorrectly) thought to be absent. The more remote and less populated a place is, the more out of place a human object is considered to be—like the plastic bag found in the bottom of the deepest place in the ocean, the Mariana Trench. There are places where litter is acceptable and others where it is not. What is the proper place for space junk? You could say it is the atmosphere: that abandoned satellites and debris should be cremated, ashes to ashes, dust to dust. There’s a contradiction here. We’ve placed junk where it is perpetually “out of place” as a human object, but in another sense, this is its natural place.

The rise of space junk coincided with the growth of the environmental movement, which didn’t view human industrial activities as the inevitable advance of human civilization, but as destructive to Earth. These changing attitudes were partially driven by the new views of the whole Earth from the early satellites and missions to the Moon in the 1960s. People had been imagining Earth from outside for hundreds of years, from astronomer Ptolemy in the 2nd century CE to Camille Flammarion in his 1880 book Astronomie Populaire. My favorite example appears in a 1965 episode of the space sitcom I Dream of Jeannie, when Major Tony Nelson performs a spacewalk in a silver spacesuit with a dull grey Earth in the background.

The first satellites with cameras had been sending back images of parts of Earth’s surface since Explorer VI in 1959. The Soviet Molniya 4 satellite returned a picture of a grainy black-and-white whole Earth, but partially in shadow, in 1966; the US AST-3 satellite captured the complete globe in color in 1967. In 1968, astronaut Bill Anders, on board the Apollo 8 lunar orbiting craft, took the celebrated picture of Earth rising over the lunar horizon. The most famous image is perhaps the Apollo 17 Blue Marble, from 1972, where the entire planet is lit, in daytime. For the first time we could feel Earth as a single entity—the “Spaceship Earth.” In this metaphor, Earth is a sealed capsule of life floating in the ocean of space. The integration of humans and nature in the Earth system is defined in opposition to the menace of cold and lifeless space outside. These ideas meshed powerfully with the rise of environmental awareness.

While influential, the whole Earth and Spaceship Earth visions were not without problems. The invisibility of national boundaries gave the illusion of global solidarity and was very inspiring, but this only served to mask the fact that wars were raging on the surface, there was massive economic disparity between the “developed world” and the “third world”, and only a privileged few—particularly the US military pilots from whom astronauts tended to be drawn—got to see this view. More particularly, they re-centered Earth, and made the Earth orbit region seem like “outside”. They separated Earth and space and helped create a place where junk was invisible.

By 1970, hundreds of spacecraft had been launched. Some of the upper stage rockets were exploding because of the instability of their remaining fuel, creating a population of fragments. The space science community started to be concerned about the long-term impacts foreshadowed by the accumulation of this junk. In 1973, space lawyers Paul Dembling and Swadesh Kalsi talked of space debris as pollution on the last frontier.

A few years later in 1978, two space scientists predicted a frightening future if space junk was left unchecked. One of them was Burton Cour-Palais. He had worked on the problem of protecting astronauts from impacts by meteoroids, both inside their spacecraft and outside in their spacesuits. In the mid-1970s, he shared an office with Donald Kessler at NASA. Kessler had investigated the risk of collision with meteoroids for spacecraft in the asteroid belt, and he saw the immediate analogy to space junk in Earth orbit. There wasn’t a lot of sympathy for focusing on a problem for which there was no solution, but Kessler wouldn’t stop talking about it, earning the nickname “Mr. Orbital Debris”.

I needed help to convert the weight of space junk into the equivalent number in cane toads but here for your edification is the number: there is 8.4 million cane toads’ worth of junk up there.

The pair argued that the real risk to astronauts and spacecraft was not meteoroids, but being hit by space junk. The higher-ups “did not want to know about it at the time”, Cour-Palais recalled in an oral history interview. So they started looking at the data about exploding rocket bodies left in orbit. They combined this with tracking data from NORAD (North American Aerospace Defense Command) and other organizations to prove that this was a major source of orbital debris. The higher-ups had to start listening.

Then Kessler and Cour-Palais projected the data they had into the future and came up with the worst-case scenario for space junk, now called the Kessler Syndrome. A cascade of random collisions creates so much debris that Earth is cut off from space, even if nothing new is ever launched into orbit. Each collision creates new pieces of junk, which collide with each other in ever-increasing numbers. The paper, “Collision frequency of artificial satellites: the creation of a debris belt”, is elegantly and succinctly written, its strongest points delivered matter-of-factly. Kessler and Cour-Palais state that if their scenario comes to pass, “all missions would have to expect damage in certain regions of space”. At its most extreme, any space vehicle trying to leave Earth would be smashed into smithereens. It’s the robot equivalent of the Greenhouse Effect–a runaway feedback mechanism that once started can’t be halted. From this perspective perhaps I shouldn’t compare satellites and space junk to elephants: perhaps the more appropriate analogy is cane toads. They were introduced to Australia in 1935 to control pests in Queensland sugar cane crops, but have got out of control and are spreading everywhere. I needed help to convert the weight of space junk into the equivalent number in cane toads but here for your edification is the number: there is 8.4 million cane toads’ worth of junk up there.

The idea of a cascade of collisions came from theories of planetary formation, where collisions between bits of space stuff cause the eventual formation of a ring or belt, just like we see around the ice and gas giant planets of Neptune, Uranus, Saturn, and Jupiter. Eventually, Kessler and Cour-Palais proposed, as orbits decayed and became more similar, Earth might acquire visible rings, the only inner solar system planet to have them. I can’t help thinking that this inadvertent work of planetary engineering could be quite beautiful. How would it feel if the Kessler Syndrome became reality? Canadian science fiction writer Karl Schroeder explored this in a short story called “Laika’s Ghost” that describes a world where access to space has been closed off by catastrophic space debris events. One of the characters, Ambrose, laments:

“Then when I was twelve the Pakistan-Indian war happened and they blew up each other’s satellites. All that debris from the explosions is going to be up there for centuries! You can’t even get a manned [sic] spacecraft through that cloud, it’s like shrapnel. Hell, they haven’t even cleared low Earth orbit to restart the orbital tourist industry. I’ll never get to really go there! None of us will. We’re never getting off this sinkhole.”

Earth governments—”they”—appear helpless, unable or unwilling to initiate a clean-up operation. It’s a bleak vision of what many predict will happen if nothing is done about orbital debris, and, just as importantly, if we don’t prevent war in space. In 2007, China fired a missile at one of its own satellites to see if they could hit it from Earth. Well, they could; but the break-up of Fengyun 1C created so much debris that experts said we were now twenty years closer to the Kessler Syndrome than if the test had never taken place. So when Schroeder talks about war in space, we already have an idea of how that might play out.

Excerpted from Dr. Space Junk vs the Universe: Archeology and the Future by Dr. Alice Gorman. Reprinted with permission from The MIT Press, 2019.