Cat's guide to interplanetary transfers

[CatWithAJetpack]

Hello, welcome to my guide, hopefully this will help you get interplanetary!

 

You may be wondering, "Well I made it to The Mun and Minimus, now what?" the answer, Jool! Though far away, Jool has a MASSIVE gravity well, this makes it easy to get an encounter, and learn about how interplanetary transfer works.

Step 1: Build an interplanetary vehicle.

Now Explosive Aerospace™ has prepared a craft which you can download, or if you're feeling up to it you can build your own.

download instructions:

1. Download craft (click me)
2. Navigate to C:\Users\*USERNAME*\AppData\LocalLow\Intercept Games\Kerbal Space Program 2\Saves\SinglePlayer\*SAVENAME*\Workspaces
3. Put the craft file into the workspaces folder

If you decide to build your own here are a few pointers:

• Have at least 2200m/s Dv in your transfer stage.
• Don't include Kerbals yet we are doing a flyby / impactor mission.
• Use RTGs for power generation the sun barely works that far away.
• Include the largest comms dish for constant communication with the KSC.

Step 2: Wait for a transfer window.

"What is a transfer window?" you may ask, a transfer window is a period of time during which a spacecraft orbiting one celestial body can travel to a different body and enter its SOI without excessive expenditure of Delta-V.

Here is a transfer window map, basically you align Kerbin as shown in the map and wait for your target planet to align. Usually, we say the angle of the transfer window when referring to it. We find the angle of the transfer window by drawing a line from Kerbin to Kerbol (The Sun) then to target planet, the angle formed at the sun would be the transfer angle e.g. the transfer to Jool would be 90°.

 

(Map credit)

Now time warp to a Jool transfer window. Tip: if you can't get to 1,000,000x time warp spawn a craft, recover it without launching, then warp in the tracking station.

Step 3: Launch time

Just get into an equatorial eastern orbit, fairly simple stuff.

If you are using the "stumpy" spacecraft you may want to know how to fly it.

• Start your gravity turn later (1500m) the rocket can be a bit unstable at times.
• The spacecraft uses "asparagus staging" just watch the Dv number at the staging GUI and Stage when it reaches 0.
• You will use a bit of fuel from your transfer stage to reach orbit, your remaining Dv should be around 2150, that is still enough don't worry.
• Deploy the faring at 60,000m
• sometimes the decoupler that separates your lower stage from your upper stage may not work, to fix this quicksave (F5) then quickload (F9).

Step 4: Setting up your transfer

Now it's time for the hardest part (don't worry it won't be that hard) setting up your interplanetary transfer!

Step 0 - Set Jool as your target.

Step 1 - Create a maneuver node a little after where the sun sets on the planet, we do this is to leave on Kerbin's prograde side, this gives you a large speed boost.

Step 2 - Pull out your prograde node until you get an interplanetary transfer, this should cost about 2000m/s of Dv and it should look something like this:

Step 5: Preform your burn!

It's time to go, perform your burn! Make sure you keep an eye on your orbit just in case.  If you are happy with your encounter, you can stop now and time warp to your flyby, but if you are doing an impactor mission or you didn't get an encounter continue.

Step 6: Mid-Course Correction

Mid-Course correction is an important step in interplanetary exploration. It allows you to get a better orbit around another planet or crash directly into it. Mid-Course correction a navigational correction made to the course of a space vehicle at some point between the beginning and end of its journey.

Mid-Course corrections are usually very low on the Dv amount, what you need to do is mess around with a maneuver node until you get the desired orbit. For your mission it may be similar to this: (Blue: current orbit | Orange: Changed orbit)

Congratulations!  You have just gone interplanetary, Enjoy the views!

[FuelX]

Thank myou. I will try your tip for the 1,000,000x time warp! 

Do your pods always land on their legs?

[schlosrat]

Great guide @CatWithAJetpack! If you'd like your staging on your final motor to work reliably I recommend that you leave the decoupler in stage 6 and insert a new stage 7 between 6 and 7 placing the final motor in that. This, and just a little coasting time between staging events, will totally solve the issue you sometimes see where the upper stage is firing and it's dragging an empty lower stage behind it. The issue is that KSP2 has a bug with how it handles stages. If you combine a decoupler with the motor above it you're just rolling dice for a little mini-kraken to come along and weld the lower stage to the upper one.

Very pretty little rocket, BTW!

[CatWithAJetpack]

16 hours ago, schlosrat said:

Great guide @CatWithAJetpack! If you'd like your staging on your final motor to work reliably I recommend that you leave the decoupler in stage 6 and insert a new stage 7 between 6 and 7 placing the final motor in that. This, and just a little coasting time between staging events, will totally solve the issue you sometimes see where the upper stage is firing and it's dragging an empty lower stage behind it. The issue is that KSP2 has a bug with how it handles stages. If you combine a decoupler with the motor above it you're just rolling dice for a little mini-kraken to come along and weld the lower stage to the upper one.

Very pretty little rocket, BTW!

Ah I had no idea, I always just put them together to make it easier.  Thanks, I also really liked the way the rocket turned out.

[Gargamel]

Moved to tutorials 

[JoeSchmuckatelli]

@CatWithAJetpack

Duffer Question:

When in orbit and selecting Duna as the target - should I get (don't know what to call it) the plane change icons to show up?  I see those when going to the moons; if I'm off plane I know to adjust the plane to improve my chances of an intercept. 

In my current game, I'm trying to get to Duna... but have no plane change icons (the places where you burn normal/antinormal to ensure alignment with the target).  Don't know if that's normal or not.

...and for some reason the planets won't move when I'm warping in Space Center view; so maybe something else is going on?

[schlosrat]

1 hour ago, JoeSchmuckatelli said:

@CatWithAJetpack

Duffer Question:

When in orbit and selecting Duna as the target - should I get (don't know what to call it) the plane change icons to show up?  I see those when going to the moons; if I'm off plane I know to adjust the plane to improve my chances of an intercept. 

In my current game, I'm trying to get to Duna... but have no plane change icons (the places where you burn normal/antinormal to ensure alignment with the target).  Don't know if that's normal or not.

...and for some reason the planets won't move when I'm warping in Space Center view; so maybe something else is going on?

TL/DR: just shoot for an equatorial orbit around Kerbin and go for it!

I think you’re referring to the line for the ascending and descending nodes. This is defined when your orbit and the other body’s orbit are around the same body - like when both your craft and the moon you’re targeting are orbiting Kerbin. If your craft is not already in the same plane as the target body then there exists a line where the plane of your orbit intersects the plane of the other body’s orbit. Changing planes is cheapest at the ascending and descending nodes. And especially so at whichever node is highest.

When your craft is orbiting Kerbin and the body you’re targeting is another planet orbiting Kerbol, then this isn’t defined. Yes, both orbits are planes, and yes they intersect, but the intersection wont help you as the orbits are not both about the same body. If you were to depart Kerbin’s SOI and be in an orbit about Kerbol, then this would be defined and you could wait for the ascending or descending node - but the wait may be a very long one.

Fortunately, all the planets except Eeloo are nearly coplanar. This means you really don’t need to worry about a plane change as long as you leave Kerbin in an orbit that’s near the plane of Kerbin’s orbit about Kerbol. Since Kerbin’s orbital inclination is 0, and I believe it’s axial tilt is also 0, then a perfectly equatorial orbit about Kerbin will give you an Kerbol centric transfer orbit that has 0 inclination as long as you burn prograde to depart. Since Duna’s orbital inclination is 0.06, you’re basically in a coplanar transfer orbit!

https://wiki.kerbalspaceprogram.com/wiki/Kerbin

https://wiki.kerbalspaceprogram.com/wiki/Duna

 

Edited March 9, 2023 by schlosrat

[JoeSchmuckatelli]

12 hours ago, schlosrat said:

NLDR

Thanks for the very cogent answer! 

Edited March 9, 2023 by JoeSchmuckatelli