Mun 180

[Nich]

So I had an interesting solution to a problem the other day.  I needed to do a 180 around the mun for a rescue contract.  I was in a highly eccentric orbit and I managed to do it for 10 dv.  Can you guess how?

[The Aziz]

The higher you are, the cheaper inclination changes are.

[Martian Emigrant]

Your Ap was near the edge of the SOI. You reversed your orbit once there.

 

ME

[PunkyFickle]

I don't quite understand the wording of the problem. You are above the Mun in a highly eccentric orbit and your target is also in orbit, but on the other side, isn't it? And in a circular orbit, I guess, so you have to not only change your inclination (about which burning closer to the apoapsis and farther from the Mun makes it indeed cheaper) but also circularize, which would in no case cost only 10 m/s. By the way, your target will perform several rotations by the time you reach it, so it won't be on the other side for very long...

Well, I am confused about what "I needed to do a 180 around the mun" means.

Edit : OK, time to go to sleep for me. @Martian Emigrant is right.

Edited February 2, 2019 by PunkyFickle

[Jon Tash]

You went back to kerbin orbit and then burned to get in a retrograde orbit on the Mun (compared to whatever you were suppose to save) to get it?

Edited February 3, 2019 by Jon Tash

[Nich]

@Jon Tash hit it on the head.  Because the Muns SOI is so small even at AP a 180 will cost 120ish dv.  Instead I did a 6 dv burn at and PE left the Muns soi and timed it so that my exit vector was ahead and above the Muns orbit so I would reencounter the Mun in about a 1/4 orbit but in the opposite direction and then had a 4 dv burn to capture.

Forgot how to imbed images so here is a link.

https://imgur.com/a/AUyJZwF

[Superfluous J]

29 minutes ago, Nich said:

Forgot how to imbed images so here is a link.

https://imgur.com/a/AUyJZwF

Click the image to make it big, then right click it and "copy image link" or whatever your browser says to do the same.

Then just paste that link here.

[Jon Tash]

6 hours ago, Nich said:

@Jon Tash hit it on the head.  Because the Muns SOI is so small even at AP a 180 will cost 120ish dv.  Instead I did a 6 dv burn at and PE left the Muns soi and timed it so that my exit vector was ahead and above the Muns orbit so I would reencounter the Mun in about a 1/4 orbit but in the opposite direction and then had a 4 dv burn to capture.

Forgot how to imbed images so here is a link.

https://imgur.com/a/AUyJZwF

I was pretty logic to me to do that manoeuvre.

[dr.phees]

WARNING: THE FOLLOWING SENTENCE MIGHT CONTAIN IRONY

That's exactly like NASA does it!

 

Edit: Added warning announcement.

Edited February 5, 2019 by dr.phees
Some people missed the IRONY.

[Pecan]

On 2/2/2019 at 9:07 PM, Nich said:

I needed to do a 180 around the mun ... can you guess how?

Waiting half the orbital period would have done it.

[KerikBalm]

On 2/3/2019 at 9:23 PM, dr.phees said:

That's exactly like NASA does it!

NASA would insert into the right inclination to start with.

This seems more like an abuse of the patched conics system

[Nich]

I had 2 rescue contracts I wanted to do with 1 station in a highly elliptical orbit and a kerbal mover.   Orbits were 167 degrees inclination from each other

I feel like it is more like a 2 body version of Lagrange point unstable orbit maneuver.

Edited February 5, 2019 by Nich

[Bogen]

12 hours ago, KerikBalm said:

NASA would insert into the right inclination to start with.

This seems more like an abuse of the patched conics system

While the specific maneuver Nich used depends on patched conics, in real life you could do this via L1.