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?
7
votes
2
answers
530
views
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 ...
- 1,546
7
votes
1
answer
237
views
Textbook or scholarly discussion of equations used by the SDP4 part of SGP4 TLE propagators beyond Space Track Report #1?
(the famous) Space Tract Report #3 discussed at length in Dr. T.S. Kelso's Revisiting Spacetrack Report #3, AIAA 2006-6753 Describes the "deep space" corrections to the original SGP4 known ...
- 148k
5
votes
2
answers
301
views
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 ...
- 148k
8
votes
2
answers
427
views
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, ...
- 48.7k
1
vote
1
answer
161
views
Why can't custom-made TLEs for the DSCOVR launch booster in orbit around Earth work with SDP4?
This fascinating answer to Why has no TLE been published for the DSCOVR satellite and the Falcon 9 R/B? presents links to custom-made TLEs for the Falcon 9 rocket body that put DSCOVR into orbit, and ...
- 148k
5
votes
1
answer
663
views
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 ...
- 53
3
votes
1
answer
536
views
Confused about SGP4 implementation published by celestrack
I was trying to understand how SGP4 computes the propagated position I had a look on the original publication paper but i have not found a satisfactory answer.
So I had a look to the Matlab ...
- 103
5
votes
1
answer
770
views
How can Earth-Centered Inertial (ECI) coordinates be properly called "inertial" if the Earth's orbit is always accelerating towards the Sun?
I've just realized (again) that I don't understand anything, something that often happens to me after reading a @DavidHammen answer.
How can Earth-Centered Inertial (ECI) coordinates be inertial if ...
- 148k
3
votes
2
answers
355
views
SGP4 on Systems Tool Kit (STK); how to check if SDP4 deep space correction is implemented?
I am doing orbit propagation for a geostationary satellite which requires the deep space corrections of SDP4. See my previous question SGP 4 for Geostationary Satellite.
I am using SGP4 on STK, but, ...
- 513
6
votes
1
answer
343
views
SGP 4 for Geostationary Satellite
I have read some sources that say that SGP4 is for satellite which have orbital period less than 225 minutes. For orbital period more than 225 minutes, we should use SDP4 instead.
I need a ...
- 513
4
votes
3
answers
1k
views
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, ...
- 43
3
votes
2
answers
315
views
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 ...
- 359
6
votes
1
answer
322
views
Is TESS really lost? What does Celestrak mean exactly?
From this answer to the question What artificial satellite has the farthest orbit around the Earth?:
I found the following "far out" spacecraft:
TESS (Transiting Exoplanet Survey Satellite)...
- 148k
1
vote
0
answers
361
views
Cis-L2 Libration Point Halo Orbit
Queqiao became the first satellite to orbit the Cis-L2 libration point (far side of the moon). Link: https://en.wikipedia.org/wiki/Chang%27e_4
Does anyone have any insight on how to model this orbit ...
- 11
6
votes
2
answers
2k
views
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 ...
- 148k