6

Skimming CCSDS RECOMMENDED STANDARD FOR ORBIT DATA MESSAGES, it looks to me like three different message types are defined: Orbit Parameter Message (OPM), Orbit Mean Elements Message (OMM), and Orbit Ephemeris Message (OEM). OPM gives position and velocity and optionally "osculating Keplerian elements". It is "suited to exchanges that "do ...


6

For Python and TLE propagation using SGP4 one very handy option is https://rhodesmill.org/skyfield/ As you probably already know a TLE is a strange animal. It does not really contain proper orbital elements, but instead is engineered with one purpose; to be fed into SGP4 so that that will generate reasonable position information for at least a few days ...


5

Changing only the data wouldn't do much, if it were just fed to the same old SGP4 we've been using for decades. However, to my delighted surprise, at long last, the US government has provided a new propagator for public use! I haven't seen it announced anywhere, but if you go to https://www.space-track.org/documentation#/sgp4 and download the zip file, the ...


5

This has to do with ambiguities in the definitions used for certain terms, and software doing strange contortions to avoid breaking backwards compatibility. The USAF's family of Simplified General Perturbations propagators are based on mean element theories of orbital motion. However, there are multiple ways to define and compute mean motion, and ...


4

You are mixing some topics. The TLE Format is not running out numbers (directly), the 5-digit NORAD ID is and the TLE-Format is not allowing more than 5 digits in the Satellite catalog number field (columns 3-7). NORAD / USSF are planning to change their designator to a 9 digit number (allowing up to 999 999 999 designated objects), because more than 99 999 ...


4

While this was too rushed out question, in the mean time I managed to find an answer while playing with already existing TLE parsers. The main difference between the + and - sign is that - multiplies whatever is left of the sign with 10 to the negative value, while the + multiplies whatever is left of the sign with 10 to the positive value. Example: If we ...


3

I find Ryan C's answer interesting... but I've never actually interpreted the documentation that way. It's difficult to be certain, since all official TLEs have had ephem type 0. But I (and others with whom I've discussed the matter) have assumed that ephem type 0 means "use SGP4 if you've got 6.4 or more revolutions/day; otherwise, use SDP4", ...


2

You can download TLE data for each of these orbit regimes separately with the click of a link at https://www.space-track.org/#recent after registering and agreeing to the terms of the site. The definitions used there are: HEO: Eccentricity > 0.25 GEO: 0.99 <= Mean Motion <= 1.01 and Eccentricity < 0.01 MEO: 600 minutes <= Period <= 800 ...


2

Changes due to the new fence: The new space fence will most likely lead to better orbit estimates for most objects currently in the catalog, as they will be observed more often. It will also detect more and smaller pieces of debris. They might only be detected if they pass at high elevation and less likely at low elevation. Consequently, their accuracy ...


1

What exactly is your goal? Are you looking for errors in the TLE data, or are you trusting them to be correct and using their distribution to tell you what sorts of orbits are unusual for satellites to be in? Trying to spot errors just by statistical means is inherently murky; if you want to do that for real, you need better orbit data to compare against. ...


1

I found Hujsak 1979 -- its title is "A Restricted Four Body Solution for Resonating Satellites Without Drag", but the linked pdf shows it is also Spacetrack Report #1. Four body means Earth, Moon, Sun, and satellite. There is a lot of integration going on: some things are averaged three or four times, over different periods with respect to ...


1

There were 5 servicing missions to HST: Servicing Mission 1 in December 1993 Servicing Mission 2 in February 1997 Servicing Mission 3A in December 1999 Servicing Mission 3B in March 2002 Servicing Mission 4 in May 2009 The decrease in tracking frequencies in your plot coincide with SM 3B and SM4. At the end of each mission HST was boosted up to a higher ...


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