Help with a Comet crash into Earh

[TechkNighT]

Hello, i'm trying to simulate an Comet impact like Tunguska early 1900's impact, and i'm having dificulties in creating the orbit of such a "thing"

Anyone can give me a help

I've alreafy read many guides about generating .ssc files and orbital components, the real problem is, having some orbital parameters like period Majorsemiaxis, pericenter distance, eccentricity and inclination, how to make a encounter with this object and Earth in a given time (let's say july, 15,2089).

Thanks in advance.
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