How to read the map inorder to not crash into the mun.

[nascarlaser1]

Hi guys!

Good news, I finally managed to hit the Mun! Bad news, I hit at about 400 m/s because I read the map view wrong. Can someone explain how to use the map view to get to the mun to me please? When I was looking at the map view, it said "Mun encounter" and then "Mun escape" so I thought I was doing a flyby. As I was approaching "Mun encounter" I left map view, but by then I was way too close to the ground to slow down enough, causing my lander to explode on impact with the ground. I've tried again and again, and each time has led me to misunderstand the map view and smash straight into the mun.

Thanks in advance!

Edited August 4, 2016 by nascarlaser1
typos

[Tex_NL]

Slightly outdated but the theory is still very relevant:

Yes, he's going to Minmus instead of Mun but that's irrelevant. Going to Mun is nearly the same.

Edited August 4, 2016 by Tex_NL

[dafidge9898]

5 minutes ago, nascarlaser1 said:

Hi guys!

Good news, I finally managed to hit the Mun! Bad news, I hit at about 400 m/s because I read the map view wrong. Can someone explain how to use the map view to get to the mun to me please? When I was looking at the map view, it said "Mun encounter" and then "Mun escape" so I thought I was doing a flyby. As I was approaching "Mun encounter" I left map view, but by then I was way too close to the ground to slow down enough, causing my lander to explode on impact with the ground. I've tried again and again, and each time has led me to misunderstand the map view and smash straight into the mun.

Thanks in advance!

You must have been viewing the map with Kerbin as the focus. Where it says "Mun Encounter", it should also say a periapsis. If that periapsis is negative, you're going to crash into the Mun. Even if the periapsis is negative, it will still show a "Mun Escape" node because it treats Mun as a point mass. In the map view, you can select Mun as the focus by double clicking on it, or by right clicking on it and selecting center view, or by clicking on it and selecting center view. I don't remember which one, but I'm pretty sure it's the first one. This way you can see your trajectory more clearly. 

[DD_bwest]

when you start your encounter with the mun, whats your Pe?    Do you focus on the mun before you start the encounter to see what your path through its SOI will be? 

If you have an encounter that crashes into the mun, it will still show an escape time even though your gonna smash into the surface.

Unless your staging, or needing to do something with your ship, somestimes its good to just stay in map mode so you can see whats happening.  if you enter the muns sphere of influence with a trajectory thatll crash into the ground,  burn to your radial out.   you should have loads of time to  correct it

 

[Zhetaan]

@nascarlaser1:

@dafidge9898 has the right idea.  However, when the periapsis goes below zero metres, it doesn't turn negative; it just disappears from map view (Kerbal Engineer and some informational mods will display a negative Pe, but map view will not).  The orbit line will still be drawn, which is what can be confusing:  the orbit lines in KSP don't detect collisions with the surface.

My usual method for getting to the Mun is to set up the burn and then click on the Mun in map mode; there should be options there to set as target and to focus view.  'Focus View' is what you want.  Then start the burn.  When it enters the Mun's sphere of influence, you'll see the line of the encounter, and as you continue burning you should see it get closer and closer to the Mun's surface.  You should also be able to shut off the engines before you too much of an encounter, if you catch my meaning.

For burns further away and where absolute precision isn't so important, I tend to do it in two parts:  I burn once to get the encounter, and then I set up a second burn to fine-tune my path to the final trajectory I want.  The Mun is so hard to miss, though (I suppose you know all about that now), that it isn't worth the trouble or the fuel to do it in two steps.

Edited to Add:  When you do get your encounter, don't let the Pe go below 10 km.  That is a good, round number that also avoids all of the highest points on the Mun's surface.

Edited August 4, 2016 by Zhetaan

[nascarlaser1]

ok thxs guys! I will try again this weekend and get back to you on my success, or failure :P.

[nascarlaser1]

Good news! I landed on the mun the Kerbal way! (and lived ). Bad news, I now need a rescue ship to get my pilot back (another post, another day ). At 5,000m above the Mun's surface my lander ran out of fuel, so I did the logical thing, I jumped out and used my jetpack to land instead. The lander vaporized on impact with the ground, but my Kerbal took his first steps on the mun! yay!!! Thanks for your help guys!!

[LN400]

Sounds like it went better than my first attempt then. Look up confusion in a dictionary and you see a picture of me getting all the controls wrong  Congrats.

 

Just a tip: If you orbit say one body and have the trajectory set up for an encounter, hitting the tab key in map view, or select focus view in the pop up menu there, let you see up close how the trajectory will be (at least it will be close but it may change a little bit during the trip over). You can then have a close up view of what fiddling with the maneuver node will do. It is particularly useful if you need a particular orbit once there.

[nascarlaser1]

1 hour ago, LN400 said:

Sounds like it went better than my first attempt then. Look up confusion in a dictionary and you see a picture of me getting all the controls wrong  Congrats.

 

J You can then have a close up view of what fiddling with the maneuver node will do. 

I did this without maneuver nodes . I have not the slightest of an idea on how to use them .

[LN400]

28 minutes ago, nascarlaser1 said:

I did this without maneuver nodes . I have not the slightest of an idea on how to use them .

The maneuver node can be a bit of a bite to chew off at first. At least it was for me but it turns out it wasn't that mysterious.

To familiarize yourself with them, start with a ship in a steady orbit (no burns for the time being, just looking at the node and see how it works), Make it a due east orbit for now.

The node also relates to the nav ball so keep an eye on this one as well.

First step is with no node.

Have a look at the nav ball. Notice the prograde and retrograde markers there and make a good note on how they look and how they differ.

The prograde marker shows the direction you are currently traveling. In a steady orbit it should be at or very near the horizon line on the nav ball.

The retrograde marker shows the exact opposite direction of which you are traveling.

Again, make a good note on how these two markers look.

Turn the ship to point towards the planet you are orbiting. There you will see a blue marker. Turn the ship around again pointing directly away from the planet and you will see another blue marker. Again  make ery good notes on how they look and how they differ,

Finally, turn the nose of the ship due north and then due south to see 2 pink/red markers on the nav ball. Again make a note on how they look and how they differ.

Now picture this:

The orbit is in a plane. Imagine a circle or ellipse on a sheet of paper.

At any point your ship is at, the yellow markers are on a tangent line to that orbit.

At any point your ship is at, the blue markers are on a line going from the center of the planet through your ship and out into space. It's a radial line.

At any point your ship is at, the pink markers are on a line going through the paper at a right angle.

 

Now place a node anywhere on the orbit line in map view. If it's small and orange, click on it to blow up the size and bring up 6 icons attached to it.

Note how those 6 symbols match the 6 markers on your nav ball. What they do is let you decide along which of the 3 axis I described above you will make the burn. Each axis goes in 2 directions, but think of that as say, positive and negative burns.

By left clicking and dragging the symbols you can add delta v to the burn along any of the 3 axis and any combination of them.

If you want to increase the orbital altitude, click and drag the prograde marker.

If you want to go lower, click and drag the retrograde marker.

If you want to change the eccentricity of the orbit, or the focal points of the ellipse, click and drag the blue markers.

If you want to change the inclination, click and drag the pink markers.

All the delta v you add to the burn along all axis are "added up" to a total delta v to burn for.

 

Best tip after all this is to set up a node and just toy around with those 6 markers and watch how the projected orbit/trajectory changes. Learn by doing.

 

After that, try a polar orbit and see how the markers on the nav ball are oriented now and how the markers on the node are oriented.

Notice the blue marker that appears when a node is set up. That is the direction you need to point the nose for the burn.

Also notice that the markers on the ball tells you which direction the node markers "act" when you drag them around.

Finally, when the node is enlarged, you can right click on it to get 3 more symbols

A red x for deleting the node

+ and - for setting up the burn at a later pass, that is not neccessarily the upcoming pass. This trick is particularely useful when you plan a rendevouz with a ship or another body.

 

Hope this is of some help.

Edited August 6, 2016 by LN400
typo