Question From the moon to ISS

[samuelemoon]

Hi everyone,
I'm new on this forum and after for mounth of plaing with Orbiter i'd like have some help to try to come back from the moon and go to the ISS, i'm able to do it but in a very poor way.. i mean that i'd like do it using trans x Mdf or other Mdf.. i'd like to know if there is a sistem to decide when start the engine fron the orbit on moon and how much delta v i need to have a good traiectory to earth.. and how to arrive in the right orbit on earth to dock to the Iss..
Thank to all.. and good flight

 

[Bj]

There are a lot of links on this thread that goes to various tutorials.

http://orbiter-forum.com/showthread.php?t=225

and how to arrive in the right orbit on earth to dock to the Iss..

There is a simple way to change your inclination when coming back from the moon.

When on your way back to any planet, look on your orbit MFD. On the bottom of the MFD there is going to be a number like (.46) 1.0 means that you are entirely in the planets SOI. When this number increases to .50 (say your on your way back to Earth) then the Map MFD will start displaying lines of your current orbit path, showing your inclination. If you are on the right trajectory, you could just click Normal +/- to change your inclination. Which one you click manages which way you point and if you add or subtract to the inclination.

hope that helps,
Happy orbiting

 

[agentgonzo]

http://flytandem.com/orbiter/tutorials/lunar_return/index.htm

 

[flytandem]

It's been 7 months since I have fired orbiter up (busy with life ) but I think I can still take a stab at some input.

If I were orbiting the moon and wanted to drop back to earth and rendezvous with the ISS there are a couple of things I would consider.
1. A lot of plane change can be done back at Earth while aerobraking. This assumes you have both some aerodynamic lift and won't burn up pulling a couple or 3 G's while inverted. The stock DG works well.
2. I would look at it from the ISS point of view. Change to being in the ISS and bring up Map. If the moon isn't currently sitting in a position in plane with the ISS orbit then something dropping back from the moon at that time won't be able to exactly be in plane with the ISS.

So you could sit there in orbit at the moon for the days it takes to be in plane with the ISS. Or just bring it back and plan on the plane change while aerobraking.

 

[Andy44]

I have used flytandem's method (2) in the past. Switch to the ISS cockpit, bring up Map MFD and look at the Moon's position, the actual Moon, not it's ground track.

About once every two weeks you will notice the Moon will lie in the orbit plane of the ISS. About 3 days before this happens, you will want to make your eject burn from lunar orbit and fall towards Earth. Switch back to your moonship and do so.

As you are falling towards Earth, you can set up the Align Planes MFD so that Earth is the primary body, and the target vessel is the ISS. By thrusting plus normal or minus normal you should be able to get pretty close to being in the ISS's plane, since you should've been within a few degrees to begin with. Until you get very deep in the Earth's SOI, you will have to make corrections to stay in the ISS's plane.

See if this works for you.

 

[flytandem]

Hi Andy,
Are you sure that you want to leave the moon 3 days before it crosses the plane of the ISS? I get the impression that leaving lunar orbit as it exactly crosses the ISS plane might be better. The trick would be to leave the moon in a direction to be falling with the correct inclination to stay in plane with the ISS through the entire return to earth. It might be better (easier) to start by sitting parked on the lunar surface so you could choose the best orbit inclination at the moon instead of already orbiting the moon.

Anyway, I would start sitting in the ISS, Map, target moon, advance time until the moon is just about to cross the ISS orbit, slow to real time.

Then switch to sitting the ship orbiting the moon. Set up a TransX escape, stage 2 target ISS, scale to view target, graph projection plan, and have the plan with some negative prograde to drop the Pe to the Earth so you can see it, then some plane change to rotate the ISS orbit fairly circular, (keep adding or removing prograde to keep the Pe correctly touching the Earth atmosphere.

After the plan is set up, back at stage 1 the plan will show up as the yellow dashed line. Drop the Pe of the plan to match the ship orbit, and the orientation of the plan to bring it in plane with the ship. if graph projection is plan, the ship orbit will look circular (or at least whatever ellipse it actually is). Then set up a maneuver so that visually the yellow dashed line of the maneuver matches the size and position of the plan as close as you can see. The two yellow lines will appear as one line pretty much if you set it up well. Burn the maneuver and once free of the moon perhaps a couple of MCC maneuvers to arrive in phase (just behind) the ISS to reduce the number of orbits to intercept after aerobraking. Do fine tuning of the alignment with ISS during aerobraking.

I set this up (first TransX work in 7 months) and saved but for some reason the save didn't keep the TransX plan when I fired the saved scenario up. If I had more time I would try to find out why that happened. I wanted to post the scenario but,... oh well... something about mice and men.

best regards,

rob

 

[flytandem]

scenario

I went back and found how to get the saved scenario in TransX. Here is a random orbit (launched Brighton about heading 070 degrees. Warped ahead until the moon was about to cross the plane of the ISS at Earth. Then set up the lunar orbit ship with escape to Earth and set up a maneuver to approximately match the plan. Completing the maneuver burn and not doing any MCCs I found it was a fairly close match (3 or 4 degrees) with the ISS but the Pe was about 3M above the atmosphere. A couple of small MCC would easily drop the Pe into the atmosphere and the plane alignment is easily fine tuned while aerobraking.

I attached the scenario but don't know if it worked so here's the scenario in text (bold) to copy paste.


BEGIN_DESC
From a random orbit at the moon, TransX set up to eject to match the ISS orbiting the Earth.
END_DESC

BEGIN_ENVIRONMENT
System Sol
Date MJD 52019.1753720304
END_ENVIRONMENT

BEGIN_FOCUS
Ship GL-NT
END_FOCUS

BEGIN_CAMERA
TARGET GL-NT
MODE Cockpit
FOV 50.00
END_CAMERA

BEGIN_HUD
TYPE Surface
END_HUD

BEGIN_MFD Left
TYPE User
MODE TransX
Ship GL-NT
FNumber 2
Int 1
Orbit True
Vector 1314966.54883 1269676.2101 -164879.878311
Vector 3.99933223772 214.39752582 1623.90164804
Double 4.90279493298e+012
Double 52019.1750979
Handle Moon
Handle NULL
Handle NULL
Select Target
0 Escape
Autoplan
0 0
Plan type
0 0
Plan
0 1
Plan
0 0
Plan
0 0
Select Minor
0 None
Manoeuvre mode
0 1
Base Orbit
0 0
Prograde vel.
1 866
Man. date
5 52019.2033779
Outward vel.
0 0
Ch. plane vel.
1 -131
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 1
Scale to view
0 0
Advanced
0 0
Pe Distance
0 1867696.14366
Ej Orientation
0 -0.841248699461
Equatorial view
0 0
Finvars
Finish BaseFunction
Int 2
Orbit False
Handle Earth
Handle Moon
Handle ISS
Select Target
0 ISS
Autoplan
0 0
Plan type
0 2
Plan
0 0
Plan
0 0
Plan
0 1
Select Minor
0 None
Manoeuvre mode
0 0
Base Orbit
0 1
Prograde vel.
0 0
Man. date
0 52019.175372
Outward vel.
0 0
Ch. plane vel.
0 0
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 3
Scale to view
0 1
Advanced
0 0
Prograde vel.
1 -918.253743905
Eject date
0 52019.1728053
Outward vel.
0 0
Ch. plane vel.
1 165
Finvars
Finish BaseFunction
END_MFD

BEGIN_MFD Right
TYPE User
MODE TransX
END_MFD


BEGIN_SHIPS
ISSrojectAlpha_ISS
STATUS Orbiting Earth
RPOS -1143204.49 -6329661.84 2008146.92
RVEL -7446.515 1648.948 977.635
AROT 30.00 -0.00 50.00
IDS 0:588 100 1:586 100 2:584 100 3:582 100 4:580 100
NAVFREQ 0 0
XPDR 466
END
GL-NTeltaGlider
STATUS Orbiting Moon
RPOS 1314768.67 1274472.21 -126377.20
RVEL -20.701 190.500 1626.637
AROT -125.61 37.67 -119.37
PRPLEVEL 0:0.912 1:0.997
NAVFREQ 0 0 0 0
XPDR 0
END
END_SHIPS

BEGIN_ExtMFD
END

 

[Enjo]

You can also do the same in IMFD. While sitting on Moon, bring up Course -> Planet approach and set:
Src = Moon
Ref = Earth
Target = ISS

Manipulate the TEj to get RIn to 0. You probably know the rest.