IMFD5.3 - offset concept

[lowerlowerhk]

The manual of IMFD5.3 states that "Target oseting allows to displace the target point from the center of the target planet."

Of course I will not travel directly into the centre of the planet! I can do that easily by adjusting the PeA of target planet. So, what offset is used for other than changing my PeA? And in what situation I would want to use it?

 

[Kveldulf]

The way I understand it, is that when you do your target intercept burn, you're actually plotting a course that will impact you on the surface of your target. You'd need to do a Planet Approach burn later to raise your PeA so this doesnt happen. Offset bypasses this, and you then can set your target point... say 150k above the surface, versus doing the burn later. I think it also allows you to approach at a certain inclination, although I'm not too sure about that.

 

[Peskie]

It can also be used to target the L4 and L5 Lagrange points.

 

[Tommy]

The most common use for offsetting is to set up a free return trajectory. It is used to "lead" the planet so that you'll enter into a retrograde hyperbolic orbit around the target. The IMFD docs should contain a document called "offset proceedure" that explains how to use it for this purpose. The AMSO tutorials can also help with that.

Offset value is the distance before or after the target in it's orbit. Lon and Lat allow adjusting for altitude (somewhat) and inclination.