Moho in KSP2? Which profile?

[JoeSchmuckatelli]

I've found both of these to be useful.  At least as far as getting to Eve and Duna.  But Moho is different.

 

Interactive Illustrated Interplanetary Guide and Calculator for KSP (olex.biz)

The Calculator (immediately above) shows Moho in a VERY different position relative to the image above the link.

 

There is a considerable difference between having Kerbin at 3 and Moho at 5:30, and Kerbin at 3 and Moho at 11.

 

The question is... which is right?  Also: why?

 

[Starhawk]

It's complicated.

Moho is a special case.
It is very deep in Kerbol's gravity well and all maneuvers deeper in a gravity well are more costly in terms of dV.
It is in a very eccentric orbit around Kerbol.  This means that there is a significant difference in your relative velocity if you encounter it at its periapsis versus at its apoapsis.
It is in a very inclined orbit wrt Kerbin.  This, combined with being deep in the gravity well, means a plane change maneuver to encounter it is very costly in dV.

The upshot of all this is that transfer windows between Kerbin and Moho are definitely NOT equal.  A simple Hohmann transfer is not really the most efficient transfer to Moho most of the time.  It also means that simple tools such as the image shown or the tool linked in your post are not very effective in finding a good transfer.  To get a better idea of the variety of transfer windows take a look at this.

This is the output of the Alex Moon Launch Window Planner with the origin as Kerbin and the destination as Moho and the dates as Year 1 Day 1 (Year 0 Day 1 in KSP2).
The porkchop plot is zoomed out several times to show a longer time range which allows us to see several successive transfer windows.  Note that they are not very regular and that they vary significantly in the amount of dV they require.  They also vary rather a lot in the duration of the trip (vertical axis).

It has been said before that KSP1 has three big bosses.  Eve, Tylo, and Moho.  Eve is the hardest to return from the surface of.  Tylo is the hardest to land on.  And Moho is the hardest to get to.  The orbital insertion dV required when you actually get to Moho is insane.

Happy landings!

[The Aziz]

The picture somewhat worked for me when I tried to attempt a Moho mission yesterday, so it's in there somewhere. I could get close-ish to an encounter, I bet a small correction burn later would work. But the error margin is tiny. And thanks to trajectory bugs I completely missed it after a burn.

[magnemoe]

On 3/23/2023 at 11:44 AM, The Aziz said:

The picture somewhat worked for me when I tried to attempt a Moho mission yesterday, so it's in there somewhere. I could get close-ish to an encounter, I bet a small correction burn later would work. But the error margin is tiny. And thanks to trajectory bugs I completely missed it after a burn.

The hard part is not getting an intercept its getting an intercept there the orbital insertion is not to expensive. First time I visited with an probe I would need almost 7 km/s to enter orbit, I had 2 km/s. 
I selected to crash. 

Ion engines works nice here, but thenyou want to go into an retrograde or polar orbit as it keeps your Pe in sunlight. Moho rotates so slow it don't matter. 

 

[The Aziz]

I used the available online tools and it worked. Though, it's nearly impossible to get below 4km/s capture burn on direct approach. My ship had just over 9000m/s dv, made it there and back with a 1000 to spare. A lot of eyeballing, but it did the job.