Are We Running Out of Space Above Earth?
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Top Comments (10)
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.
So to solve this we need a vacuum cleaner. Literally.
we're going to slowly build a Dyson Sphere around the earth.
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.
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!
For once, a PBS ST episode I understood from beginning to end!
Nice to know that everywhere humans touch, exponentially rising levels of junk inevitably follow.
"Space is (as the name implies) spacious" — Matt O'Dowd (2021)
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!
My parents were terrified of paint chips when I was a child.
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Top Comments (10)
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.
So to solve this we need a vacuum cleaner. Literally.
we're going to slowly build a Dyson Sphere around the earth.
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.
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!
For once, a PBS ST episode I understood from beginning to end!
Nice to know that everywhere humans touch, exponentially rising levels of junk inevitably follow.
"Space is (as the name implies) spacious" — Matt O'Dowd (2021)
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!
My parents were terrified of paint chips when I was a child.