I would like to compute ephemerides for a satellite on a sun-synchronous orbit, starting with only the following parameters1:

  • altitude or inclination;
  • local time of the ascending or descending node;
  • starting date.

Using Orekit, I am able to compute ephemerides for a circular orbit given: the orbit radius, the inclination, the right-ascending node, the true anomaly, and the starting date.

I already know how to link altitude and inclination, and computing the orbit radius from these is trivial, but I do not know how to find the RAAN and the true anomaly given the above parameters.

I found this related question How Local time of a sun synchronous orbit is related to Right ascension of ascending node?, but there the answers do not provide formula to compute the required parameters.

Is there a way to compute the RAAN and true anomaly from the above parameters? Or another way to compute ephemerides starting only with the above parameters?

1 I am assuming this is possible since it is how a sun-synchronous orbit is specified in STK.

  • $\begingroup$ What exactly does a sun-synchronous orbit mean? The Sun does rotates non-rigidly, and so is presents a range of rotation periods to the outside observer. $\endgroup$ May 8, 2019 at 1:33
  • 2
    $\begingroup$ @Oscar Lanzi I refer you to space.stackexchange.com/questions/8194/…? $\endgroup$
    – Puffin
    May 9, 2019 at 9:49


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