How to easily put a rocket in specific position and time?

[Sivonen]

I'm thinking of a challenge, where a rocket is on a specific trajectory on a specific time. People would have to modify or build their own rocket and put it into that spot and go on from there.

To turn a rocket from collision course etc.

 

Editing a savefile would be a bit clumsy way to do that.

 

I'm a total newbie to hyperedit.

 

What would be the easiest way?

[Streetwind]

Any orbit can be defined by a specific set of numbers. This includes the position of the orbiting object at a specific point in time. Because orbits in KSP are perfectly stable and repeating, just one specific time stamp is required to compute all possible locations at all possible times.

For a practical example, pull up Alexmoon's transfer planner. Press "add body", and then switch the type to "vessel". The form you now see asks you all the information that is required, including the last field: "time of periapsis passage". There, you are to enter a specific ingame date (year/day/hour/minute/second) of this vessel hitting its periapsis. It doesn't matter which periapsis passage; any will do. As long as the orbit is known, and one single timestamp is known, you can compute the vessel's position at any given point in time - both forward and backward.

I don't really know how exactly Hyperedit or the ingame cheat menu expects such info to be entered; that's an exercise left to you. The point is that it is indeed possible to make a challenge like you envision. All you need to do is figure out what exactly you need to enter into Hyperedit or the ingame cheat menu to place the vessel in the exact place on the exact orbit at the exact time you want.

[Sivonen]

Thank you for pointing me at the right direction.

Ingame cheat menu doesn't allow to put crafts in collision course iirc.

[Sivonen]

With these instructions I managed to replicate the trajectory every time: