How does the satellite scenario account for drag, if no drag coeffincient is passed?

Hello,

I would like to simulate a couple of orbits from Keplarian Elements for a CubeSat. It all works fine except for i do not know how the SGP4 accounts for drag.

Many Thanks in advance!

[Martin Tkach]

Hello, did you ever get an answer or figure out how to pass drag properties to a satellite defined with Keplarian Elements?

Answer 1

[Ayush Anand]

Hi Steffen,

I understand you are simulating orbits from Keplerian element for a CubeSat and want to know how the SGP4 algorithm accounts for drag.

The SGP4 model incorporates drag effects through the ballistic coefficient (B*) and the atmospheric density model.

The ballistic coefficient (B*) appears in the Two-Line Element set (TLE), which is the data format used to convey the orbital elements needed by the SGP4 algorithm. The B* value is an estimate of the effects of atmospheric drag on the satellite's orbit and is related to the satellite's mass, cross-sectional area, and drag coefficient.

The SGP4 model uses an atmospheric density model to estimate the atmospheric density along the satellite's orbit. The density is used together with the ballistic coefficient to calculate the drag force experienced by the satellite. The drag force is then used to update the satellite's velocity and position over time.

Here's how drag is accounted for in the SGP4 model:

1. Atmospheric Density: The SGP4 model estimates the atmospheric density at the satellite's current altitude using an atmospheric model (such as the 1976 Standard Atmosphere model or the Jacchia-Roberts model).
2. Drag Force Calculation: The drag force is calculated based on the estimated atmospheric density, the satellite's velocity relative to the atmosphere, its cross-sectional area, and its drag coefficient.
3. Orbital Decay: The calculated drag force is used to adjust the satellite's velocity, which in turn affects its orbital elements.

You can read more about the SGP4 algorithm and how atmospheric drag, and other effects are taken into consideration in the algorithm here:

https://www.mathworks.com/matlabcentral/fileexchange/62013-sgp4

I hope this helps resolve your query!