Linked Questions
24 questions linked to/from How do SDP4's "Deep space" corrections to SGP4 account for the Sun's and Moon's gravity?
14
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How to obtain UTC of the epoch time in a satellite TLE (two line element)?
I want to convert the epoch time of a TLE to UTC. At this moment I am less interested in explanations and history - I just want to know quantitatively, with certainty, how to convert.
I'm confused ...
- 149k
20
votes
3
answers
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How can I plot a satellite's orbit in 3D from a TLE using Python and Skyfield?
I have obtained a Two Line Element (TLE) of a satellite in Earth orbit from Celestrak at https://celestrak.org/NORAD/elements/ and I would like to use it to calculate an orbit.
How can I calculate the ...
- 149k
13
votes
3
answers
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Why are Tiangong-1's Apogee and Perigee Graphs Wobbly?
The apogee and perigee graph of the Tiangong-1 space station, about to re-enter and break up Real Soon Now, is depicted in this graph (source: Wikipedia):
Why are the graphs wobbly? Is it because the ...
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9
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2
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Is SGP4 propagation necessarily more accurate near the epoch chosen for TLE generation?
This interesting answer includes a quote from Space-Track:
From Space-Track.Org FAQ
TLEs can contain future epochs.
About 20 satellites are categorized as "multi-day objects" because ...
- 149k
6
votes
2
answers
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Differences between SGP8 and the standard SGP4? Is it ever used in practice?
The Wikipedia article Two Line Element Set says:
The SGP4 model was later extended with corrections for deep space objects, creating SDP4, which used the same TLE input data. Over the years a number ...
- 149k
5
votes
2
answers
1k
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Sun-synchronous satellite orbit propagation
I'm trying to propagate the orbit of a sun-synchronous satellite. The initial data is defined by the TLE.
The orbit of the satellite is controlled by the operator ...
5
votes
1
answer
4k
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TLE SGP4 Coordinate Transformations
I am working on developing a user friendly SGP4 orbit propagator in C on a PIC24.
I have extensively read Revisiting Spacetrack Report #3 and celestrak - there are a few outstanding questions I have.
...
4
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3
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Is the amount of accurate information in a TLE equal to that of a single state vector?
My question is basically regarding whether there is orbital information "lost" when converting from a Two Line Element set (TLE) to a state vector.
Given that the following are true:
I have a TLE, ...
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5
votes
2
answers
696
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Why are Keplerian elements used in TLEs instead of Cartesian state vectors?
Propagating a state vector seems easier, you just account for the gravity, change the velocity and update the position.
It also allows to easily apply perturbations, etc.
Additionally, the ...
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4
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2
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Has a TLE ever been issued for a spacecraft trajectory not bound to Earth orbit?
This excellent answer to the question Why has no TLE been published for the DSCOVR satellite and the Falcon 9 R/B? suggests that to the best of the writer's knowledge TLEs are only issued for ...
- 149k
7
votes
2
answers
547
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For any state vector of a satellite at an arbitrary time T1, is there another state vector at a given time T2 that will result in the same orbit?
I recently found the question In a 3D space defined by semimajor axis, eccentricity and inclination, what would be the shape of the space where SDP4 works better than SGP4? and have become interested ...
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6
votes
1
answer
698
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Get dates when a satellite has performed maneuver from historical TLE data (python)?
I have been recently acquainted with orbital mechanics and am trying to do some analysis on the subject. Since I don't have subject matter expertise, I am at a crossroads with trying to decide that ...
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3
votes
2
answers
330
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When calculating the future orbit of an artificial Earth satellite, is the Moon's gravity significant or insignificant?
Imagine a mathematician is plotting the future orbit of a satellite to be launched and put in orbit around the Earth.
When they are making their calculation, is the moon so far away and the ...
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5
votes
2
answers
315
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In a 3D space defined by semimajor axis, eccentricity and inclination, what would be the shape of the space where SDP4 works better than SGP4?
@BillGray's answer to Why can't custom-made TLEs for the DSCOVR launch booster in orbit around Earth work with SDP4? is quite interesting and informative; I fail to do it justice by summarizing it as ...
- 149k
8
votes
2
answers
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How to calculate the very special orbit of 2020 SO
From a NASA JPL page:
Earth May Have Captured a 1960s-Era Rocket Booster
Source
(Sorry, I got an error when I tried to include an animated gif.)
2020 SO was captured by Earth's gravity on Nov. 8, ...
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