Can someone please explain the "closest approach" nodes ?

[Maxwell Fern]

Because they clearly don't show the points where my target and I will be the closest to each other.

I had already noticed it on some docking procedures where I was closer to my target than the node predicted, a couple of minutes before reaching that point. Plus, they don't show all the time on every orbits, which doesn't make any sense to me: no matter the targets or the orbits, there is always a point where I'm the closest.

It seems to have something to do with planes inclinations, but I'm not sure.

Then this happened:

I'm going to Duna, but I'm not getting an intercept. Closest approach seems to be 1.281km. So I try the natural thing to do:

And then BAM:

Just by simply placing a node, closest approach bounced to 30 MILLION km. You can see the node is empty though. Also, you can't see Duna here but it's just on the right, maybe 1° ahead of the "target position at closest approach", which once again just seems plainly wrong.

So, what do I make of it ? How are those markers calculated ?

[Jenteb07]

The node you have placed is on the next orbit as you can see in the amount of time till you reach your node (146 days while your initial closest approach was in 51 days). By then, when performing that maneuver Duna will be 30 million km further at the point where you are closest to Duna's orbit at 220 days.

Edited January 11, 2014 by Jenteb07

[JiWint]

one point shows WHERE you will be the CLOSEST to duna,and the other point shows WHERE DUNA will be when you will be the closest point to its orbit

[Smidge204]

I'm going to Duna, but I'm not getting an intercept. Closest approach seems to be 1.281km. So I try the natural thing to do:

1,281,183 km. Over a million kilometers.

And then BAM: Just by simply placing a node, closest approach bounced to 30 MILLION km.

As mentioned, you've inadvertently placed the node on the orbit after your Duna closes approach (the orange ellipse) rather than your current orbit (the blue ellipse, which you can't even see because the orange one overlaps it). You might try zooming in a lot to see if you can get it on the blue line - you'll know because the little ball that shows up under your cursor will be blue, and the time to that node will be much smaller than 140+ days.

=Smidge=

[EnigmaRaptor]

The node you have placed is on the next orbit as you can see in the amount of time till you reach your node (146 days while your initial closest approach was in 51 days). By then, when performing that maneuver Duna will be 30 million km further at the point where you are closest to Duna's orbit at 220 days.

This is the answer. This thread should be marked answered.