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What is the distribution of Earth orbiting satellites by inclination? In other words, what inclinations are more or less popular? I work with Earth observation myself, where many satellites are Sun-synchronous with an inclination of around 98°, or Geostationary with an inclination of near 0°. Other orbits exist but are uncommon. Communication satellites also exist as either equatorial (such as satellite TV) or with a high inclination (such as the Iridium constellation). Are there any published statistics on satellite inclination popularity, such as a histogram/PDF of current Earth orbiting satellites by inclination?

It should be trivial to produce such statistics from published TLE files, but I couldn't find any for artificial Earth-orbiting satellites.

Question inspired by some of the discussion around: Are there any known reasons why there are no spaceports in the European Union?

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UCS publishes a database (text and excel) of "active satellites" which have publicly available data. It directly lists inclination for each, so analyzing them from that source would be pretty easy.

Pixalytics published a summary using that database that showed inclination for just the 63% of satellites that are in LEO orbits. From that summary:

  • 57.5% sun-synchronous
  • 22.85% non-polar inclined
  • 16.1% polar inclined
  • 1.69% equatorial
  • 0.76% elliptical
  • 0.08% (Actually, just 1 satellite) cislunar

Not sure exactly why 1 LEO sat has an orbit described as cislunar....

Just threw it in google sheets and generated this chart. This is using the entire 1950+ "active satellites", so includes all the GEO sats.

enter image description here

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  • $\begingroup$ Ah, so then the next step is to see what % of satellites are LEO :) $\endgroup$ – gerrit Jan 19 at 10:27
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    $\begingroup$ I haven't examined the DB myself, but their summary says 63% or somewhat more than 1200. $\endgroup$ – BowlOfRed Jan 19 at 10:31
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    $\begingroup$ That's a surprisingly high number of slightly retrograde satellites If I'd had guessed before seeing the graph, I'd have assumed that most of the "Close enough to polar to do the job" orbits would have been on the prograde side of 90°. Edit: Ah, just saw the Sun-synchronous fraction. Yeah, that would do it. $\endgroup$ – notovny Jan 19 at 15:15

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