Are We Running Out of Space Above Earth?

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While recent news about the Chinese Long March 5 Rocket made a lot of people very nervous because a 22-ton rocket was going to fall out of the sky, this sort of thing happens all the time. Boosters, dead satellites, and sometimes even old space stations get dropped out of the sky fairly often. While the litter seems a little inconsiderate, this is probably far safer than the alternative. The accumulation of space junk poses a huge risk to all human operations in space especially if we cross the threshold into the chain reaction of exponentially growing collisions known as the Kessler Syndrome.

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Hosted by Matt O'Dowd
Written by Matt Caplan & Matt O'Dowd
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[jimmurphy]

I did a high school report on this back in 1979... We all had to pick a type of pollution to report on. Mine was space junk. At the time, many kids, and the teacher chuckled as they thought I was a bit crazy. This is not new news.

[SpecialGuestStar]

So to solve this we need a vacuum cleaner. Literally.

[graphixkillzzz]

we're going to slowly build a Dyson Sphere around the earth.

[frederf]

Remember there is no part of an exponential curve where it goes from slow growth to fast growth objectively. Where e^x gets steep on a graph visually all depends on your choice of axes scales (i.e. their ratio). The "45° slope" part of the graph can be anywhere if you're free to choose scale.

I propose that all satellites have a banana cream pie on the front so if they hit it will at least be funny.

[liesdamnlies]

Well, if the pandemic taught us anything, it's that people in general can't grasp exponential growth and its implications. I don't have much hope on this one.

[weiniesail]

For once, a PBS ST episode I understood from beginning to end!

[katalysis]

Nice to know that everywhere humans touch, exponentially rising levels of junk inevitably follow.

[TheAlkhemiaStudio]

"Space is (as the name implies) spacious" — Matt O'Dowd (2021)

[victorrice]

One of the brilliant things that Kessler did was borrow some physics from the kinetic theory of gases to predict collision rates between satellites. Instead of treating orbits in the way we typically do (i.e. singular location with a nice keplerian ellipse plotted out), he instead took the long term volume of space that an object would occupy and handled each object as a spatial density value. Due to the oblateness of the earth putting torques on orbits, the line of apsides (line connecting lowest point and highest point in the orbit) and the ascending node both rotate over time, therefore you can think of this volume of space the orbit occupies as something like a spherical shell with the top and bottom cut off, with the thickness being defined by the apogee/perigee altitudes and the amount of remaining upper and lower shell being defined by the inclination (and therefore max/min latitudes). Once you've parameterized the spatial densities by radial distance and latitude for each object, you can perform a numerical integration of all objects spatial densities through a particular orbit of interest (i.e. for the satellite you are interested in protecting) to calculate a flux value. This flux can be used to determine the likelihood of collisions with other objects (assuming no mitigation strategies employed). This essentially comes out in units of "interactions/area/time", and by making assumptions about the size of a satellite, allows you to estimate how often you might be experiencing a collision for different orbits. Very awesome and out of the box thinking, with one of his original applications of these techniques being used to calculate collision rate expectations between Jupiter's Moons!

[tasogarerubica]

I first learned of the Kessler syndrome thanks to manga called "Planetes" by Makoto Yukimura, and an adaption with the same title.

This story was a contemporary hard sci-fi that depicted the threat of space debris and how commercial space corporations would deal with said problem. And like all corporate manner of cleaning after their industrial/commercial waste, they allocate a miniscule budget to their waste retrieval sector. Said sector is the setting, a crew of company misfits given the task to wipe after the corporate "ass".

The author had a pet hobby of plotting out human development in space in spans of several hundred to thousands of years. One of his editor took notice of this hobby and asked him to create a story out of it, which he took a slice out of the selfmade timeline was this, a story revolving around space debris. That in itself is crazy, but now the same author is depicting a historical retelling of vikings reaching the Americas. Makoto Yukimura is quite frankly a genius.

[borisdorofeev]

There was an anime show I'm the early 2000's about a crew of astronauts that were tasked with cleaning up space debris. Also, they work for a private corporation so imagine Amazon with part of its work as a space garbage company.

[solorobo]

Shout out to Planetes (2003). Great anime that introduced me to Kessler Syndrome and space conservation.

[renerpho]

16:25 Don't worry. That joke isn't gone, thanks to the preservation of quantum information.

[wyattnoise]

Love how if I throw a gum wrapper on the ground, it’s a fine but if you have enough money, you can just dump entire rocket stages into the ocean!

[calmeilles]

"We have collision mitigation systems planned."

Really means: "We don't have any collision mitigation systems."

[einfisch]

"...or we could take more care right now."

This was a joke so funny it made me really sad. We don't do anything down here on earth until it becomes an unavoidable and completely catastrophic problem.

[TorToroPorco]

Nice, this is great fodder for a sci-fi thriller plot that goes like this: Earth is threatened by a killer asteroid but a world wide effort to launch a series of interceptor gravity tugs / vector deflection space craft is threatened by the space junk cloud circling the earth.

[harry_page]

It kind of sounds like zombies, how if a satellite gets hit by space debris, it becomes space debris. I wonder if any satellites will start hiding the fact that they've been hit?

[thePronto]

The answer is that no one gets a license to launch anything without registering an 'end of life' disposal plan. Maybe also that they must put hard cash into a cleanup fund escrow account in case their plan fails. Or, is that already required?

[MarxistKnight]

Governments after Covid: “Wow, we should really start paying attention to scientists, they were right all along.”
Scientists: “The amount of space junk in orbit is becoming critical and could be catastrophic for our technological society. We should do something about it.”
Governments: “Oh, sounds serious. Anyway…”