Problem cant transfer back to earth

[thethedev]

If I am say orbiting the moon and want to head back to earth, the transfer MFD wont let me select earth, neither will the align planes MFD?
I can only select the moon under the earth sub menu, I tried only highlighting earth and pressing enter but that did nothing. Is their a patch or something I'm missing?
Thanks

 

[Urwumpe]

Use a different MFD there, the Transfer MFD is extremely limited and not really suitable for lunar transfers. Aligning planes is not needed for returning to Earth, since you are already in Earth orbit (since the moon is in Earths orbit). You only need to align planes to reach a desired landing site on Earth, and like all plane changes, you should do that when you are slow - and the slowest point during the voyage from Moon to Earth happens where you leave the gravity well of the moon and start accelerating towards Earth by gravity.

I recommend InterplanetaryMFD, there is also transX for such transfers included in the default orbiter installation. Not sure if LunarTransferMFD handles the return to Earth (called TEI or Trans-Earth Injection in spaceflight terms).

 

[blixel]

I'll shamelessly plug my own video here. I don't believe in short videos , so it may be too long for your taste. But if you watch it, you'll have all the information you need to return to Earth orbit. (I have other videos that cover reentry and landing.)

 

[sorindafabico]

Lunar Transfer MFD TEI is very precise if you know what you are doing.

 

[statickid]

If you want to do a hack job of it you can use this rather inefficient method, it's pretty fail safe, though.

when the Earth is at your Azimuth, Launch westward from the moon and establish a decent AP (500km or so). At The AP, fire moon orbit prograde (location A) to create a very eccentric orbit that sends you traveling towards earth (the green line). At some arbitrarily far point, a decent distance from the moon (pretty far away), fire Earth Orbit Retrograde (location B) to fall to earth (blue orbit). You can make course adjustments along the way, at your nearest pass of Earth, Fire retro again (location C) to circularize or land. With skill, you can substitute the last retro burn with an atmospheric braking maneuver.

The diagram is not to scale and does not show the TRUE path of the spacecraft, it only illustrates the logic behind the maneuvers.

This is how I learned to do it before I could use the MFD's very well or better more precise ways, so again, inefficient, but not bad with the delta glider and other such overpowered spacecraft

 

[Cras]

I find Lunar Transfer to be easy enough to use, so dont feel intimidated by it. Can even just use it to see how it goes about the burn then try it yourself.

For just getting back to earth it is as simple as selected the TEI program then asking it to come up with a solution then hit auto burn and it will go.

Of course you can take it several steps further and really get it to do some things, much like IMFD.

 

[kuddel]

@ statickid: Interesting method! I am tempted to give it a try

 

[kamaz]

My take on this -- basically the same method as statickid's. Takes 7 days instead of 3, but doesn't require advanced navigation:

1. Left MFD - Orbit, reference: Moon.

2. Right MFD - Map, reference: Moon.

3. When crossing 180 deg. longitude burn prograde raising your apoapsis above 100Mm or so. (It helps if your initial lunar orbit is retrograde and equatorial). You have entered a highly elliptic lunar orbit, with apoapsis in the direction of Earth, past the Lagrange point.

4. Right MFD - Orbit, reference: Earth.

5. Sit down and relax. When you near apoapsis, observe the G-indicator in the left MFD going down, while the G-indicator in the right MFD will be going up.

6. If you did everything right (i.e. went past the Lagrange point), Earth's gravity will capture you and you will enter an Earth orbit.

7. Burn retrograde to lower periapsis. If you want to do a direct entry, lower periapsis to be inside atmosphere (typically 60-70km) and aerobrake. Be careful though, you will enter the atmosphere pretty fast...

8. If you don't want to do a direct entry, lower periapsis to ~1000 km and then burn retrograde at periapsis to circularize.

9. Do a normal orbital reentry.

A video illustrating the concept:

Another method -- TransX + direct entry with XR2:

[ame="http://www.youtube.com/watch?v=S-hedEal3ko"]Orbiter: Moon to Earth with Direct Entry - YouTube[/ame]

 

[statickid]

Try flying around the other planets to learn about flying from the Earth to the Moon. Flying around Mars helps with understanding the moons are rather like large space craft (with gravity).

Saturn and Jupiter help to understand interplanetary travel and what it means to be in orbit around a moon but also influenced by the planet.