“On the first day of Kerbal my Kerbanauts gave to me – a KSP Orbit Mechanic program.”
The KSP Orbit Mechanic is a program which provides a robust minimum-fuel transfer analysis for Hohmann, Bi-elliptic, and inclined transfer schemes. This basically means that you select an orbital scheme then enter your know information, such as altitude, speed etc.
This means you can calculate more accurately how much fuel you will need for your journey into space.
You can find out more information and download the add-on from HERE