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Posted by: ncc1701d Aug 21 2021, 04:58 AM

This question is for someone with experience making .spk files in SPICE and using MKSPK
I am over simplifying the data values to help explain or get to the point quicker.
I am working with real data from Pioneer 12 so the data I wouldnt think is the problem

True Anomaly values on approach to Periapsis go from -30 deg then -25 deg on down to then 0 deg at the point of periapsis and then goes back up to +30 deg as it leaves periapsis.

For the sake of discussion I use these numbers for True Anomaly.
-30 deg etc. on approach to periapsis
-25
-20
-15
-10
-5
-0 deg True Anomaly at periapsis
5
10
15
20
25
30 deg leaving orbit after periapsis

Problem is when making the .spk and checking it in Cosmographia the approach trajectory looks normal but then stops right at 0 deg and then starts going backward practically overlapping the approach trajectory path.
I dont know why. Any SPICE .spk creators experience this phenom? I am using ELEMENTS for the input data type.

thanks