MO02/04-The journey

Table of content

  • 1 Setup of the ejection burn : timing
  • 2 Ejection Burn
  • 3 Injection burn at Moho

1 Setup of the ejection burn : timing

Moho is a small planet with a low sphere of influence. Its inclination is 7°. It’s not difficult to intercept it but it is really costly to be captured. For the planning, i have used the trip planner online tool of Alex Moon.

After a lot of search i found a thread on kerbalspaceprogram forum about the difficulty to establish an orbit on Moho. Alex Moon himself explains we have to forget phase angle for Moho…

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The phase angle to intercept Moho from Kerbin is -251° but this value is good for a flyby, not for a capture. If we do our ejection burn at phase angle, the required dv to be captured will be terrible, could be about 7000m/s.

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The Alex Moon  Launch Window Planner will gives us a totally different result for a transfer followed by a capture.

I have used these parameters:

  • initial orbit: Kerbin 500km (where we are)
  • destination orbit: Moho 75km
  • earliest departure: year 2, day 327

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I have setup an alarm around year 3 day 83. Now, we have to wait for 180 days.

You can notice Ker gives me a total Dv around 3000m/s because the fuel can’t find a way from the refueler to the nuclear engines. I will transfer fuel when the conventional tanks will be empty.

Meanwhile, i have some spare time to de orbit the launcher stranded in orbit. For this, i used a small asteroid hopper docked at the Ganymede station.

2 Ejection Burn

We are 1 day before the ejection burn. Time to return and have a look to the window planner.

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We add a node somewhere and move it until we are around 4h and precisely with a ejection angle of -72 on retrograde. (I could also use precisenode but it seems there is a bug in the version i use: it reset node values each time i swap between map and normal view…)

We can see the ejection angle in Ker (angle to retrograde)

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Yes, thanks to nuclear engines, it will be a 30 minutes burn…

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Almost perfect, we’ll need to do a mid course correction to match planes … and to correct what will going wrong…

So it’s BURN TIME:

I transfer fuel to keep a low torque.

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3 Injection burn and circularization

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The injection burn tooks about ‘only’ 1900m/s dv, thanks to a very well timed ejection burn!

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