Problem completing satellite in orbit around Minmus

[Spazem]

Hello,

I am a new player of KSP and its awesome. I am having real issues completing this mission. I have been trying to work it out for hours.

Basically i need to send a satellite in orbit around minmus in a specific orbit. As far as i can see the orbits are perfect but cant get the mission to finish. Here is a screenshot;

https://drive.google.com/file/d/14FdjYgK3aYT7C6zbXGLJaqJwXj_DMlte/view?usp=sharing

The only thing i can think of is even though both orbits are lined up fine in the tasks it says Longitude of ascending node. Its currently at 180 but i cant for the life of me change it.

Any pointers would be great.

Cheers 

[ElWanderer]

5 hours ago, Spazem said:

 

 

The only thing i can think of is even though both orbits are lined up fine in the tasks it says Longitude of ascending node. Its currently at 180 but i cant for the life of me change it.

 

 

Ah, yes. That means you are orbiting in the wrong direction. The simplest manoeuvre to align with the target orbit is to burn twice your current velocity magnitude, retrograde, until you're going the same speed in the opposite direction. Around Minimus, velocities are low, it is fairly cheap to change, so it may work. There are more efficient methods (generally raising your apoapsis very high, then changing direction there, then lowering the apoapsis back down) if you need them.

[Rocket In My Pocket]

Welcome to the forums @Spazem!

Congrats on experiencing one of the many "trials by fire" of any veteran KSP player.

I don't think there is a single person playing KSP who hasn't been in your shoes. "Going the wrong way around" is practically a meme around here.

Edited December 24, 2017 by Rocket In My Pocket

[Zeiss Ikon]

I don't think it's quite that simple.  Reversing your orbital direction will change your argument of periapsis (if I correctly understand that parameter), but it either won't change your ascending node position, or it'll change it by 180 degrees -- you're off by about 135 degrees.  Again, good news is, you're at Minmus, in a fairly high (for Minmus) orbit, so plane changes aren't expensive.

What you need to do is, first, make sure you're orbiting prograde; that's been covered.  Second, reduce your inclination to zero by burning normal or anti-normal at the appropriate node.  Third, set the desired inclination and nodal position by making a maneuver at the correct position in your orbit in the correct normal or anti-normal direction.  Finally, correct your argument of periapsis by making a pure prograde burn at the correct position in your orbit, sufficient to make that your new periapsis, then at next apoapsis, correct your periapsis, and burn again at the new periapsis to set the correct apoapsis value.

You need to do the steps in the order given (actually, the apoapsis and periapsis are interchangeable, but since you're given argument of periapsis it's easier to set that first), because adjusting inclination will change both apoapsis and periapsis height and orientation.

[Plusck]

18 hours ago, Zeiss Ikon said:

I don't think it's quite that simple.  ...

If you look at the screenshot, you'll see it is that simple. The AN marker is highlighted and clearly says "180°"

[Kerbal7]

Hee! Hee!

Been there done that.

You're going the wrong way!

[Superfluous J]

8 minutes ago, Kerbal7 said:

You're going the wrong way!

How do you know where I'm going?

#PlanesTrainsAndAutomobiles

[Spazem]

Thanks everyone. Lol. I did try searching forums for ages and couldn't find anything. Took me 2 mins and next to no fuel to do.  I am very happy indeed.

[Zhetaan]

On 12/24/2017 at 8:12 PM, Zeiss Ikon said:

I don't think it's quite that simple.  Reversing your orbital direction will change your argument of periapsis (if I correctly understand that parameter), but it either won't change your ascending node position, or it'll change it by 180 degrees [snip]

Unfortunately, I fear that your understanding is correct but incomplete.  You have it correct that the argument of periapsis will change, but the change is predictable:  when reversing orbital direction while holding apsis positions constant (meaning that the apsides will remain at the same points in 3-space, so you keep the semi-major axis and eccentricity), the inclination and longitude of ascending node will change by 180° and the argument of periapsis will become the supplement of its original angle.

For example, if your original argument of periapsis is 78°, then the new one will be 102°.  For angles greater than 180°, it may be easier to consider them in terms of negative angles (though it is still technically true; the supplement of 265° is 275°, which does add up to 180° if you take the full turn as a return to zero).