Tim
4 HN mentions · mentioned in 4 months, 2021–2023
4:09 · 3.1K views · Feb 3, 2021
An animated Gabbard diagram of objects in low Earth orbit from 1959 to 2021, showing altitude over time. It highlights major debris-generating events and how low-altitude debris decays out of orbit.
HN uses it to illustrate orbital debris evolution and how altitude determines how fast debris decays.
4 comments from Hacker News
>Do a search for "atmospheric drag" or anything about orbital lifetimes, gabbard diagrams [0] or the like >nothing, instead it equates all constellations and satellites together as the same thing Yet another click bait crummy article, with the obligatory "concerned astronomers" emotional tug on top but no serious engagement. And "big numbers!!" but no sort of context on if or why it's a problem. It's so tiresome how this gets trotted out over and over again. SpaceX's approach isn't bad for debris risks, it's good! The absolute best possible fail safe solution for sats is to have them low enough that they will passively deorbit very quickly without continuous boosts, or even better VLEO orbits where they must maintain aerodynamic orientation as well. Which in turn requires lots of sats that are actively replaced regularly, which in turn helps ensure updates can also be made rapidly based on real experience and they can become extremely refined. Sloppily throwing it all into some vague fear panic of "Kessler Syndrome" is not just wrong it's actively bad for that very reason vs clear differentiation between stuff at 300-550km vs 700+. Also the implication that the utility function for earth-based astronomers is unlimited and they have some special right on top, ignoring the potential future paths for improvement and approaches that would ensure that (a small tax that would go directly towards a fund for space based telescopes say). And so on and so forth. There are real importan
Probably not. Even 500,000 sattelites would still leave more than enough space between them for whatever you want. The risk would be if many of them blew up or something, creating billions of tiny pieces of debris. In that scenario, we might just wait 5 years and then most of the debris will have burned up in the atmosphere. SpaceX satellites are around 550km attitude. If someone puts satellites higher than that, collision debris will last longer, the satellites' fuel will last longer so the satellites won't have to be replaced as often, but network latencies will be higher. Seems like 500-600km is the optimal zone for the primary constellations of internet satellites. Video showing decay of debris vs. its altitude. The "X" shape is because each debris is plotted twice, once at it's perigee and again at its apogee (describing the ellipse of the orbit as they generally are not perfectly circular) this video Higher altitude satellites would be a bigger concern but these aren't a big deal.
generally when two satellites collide some debris can be shot at a higher orbit which will take forever (or will not) reenter atmosphere. See the scatterplot of debris for the Chinese collision test of 2000: [LINK] See this video for evolution of debris and altitude over time: this video
this video "Gabbard Diagram for Low Earth Orbit 1959-2021" See how the stuff in the lower left corner speeds up towards the lower left corner? That's low flying debris falling out of space.