The case for a Munar way station?

[ajburges]

So I became intrigued by the concept of a gate orbit (https://en.m.wikipedia.org/wiki/Gate_orbit) and did some scratch work...

I approximated infinite velocity of a Duna transfer orbit to be approximately 815 m/s. That puts the gate orbit at a radius of 1e7 m. Transfer window calculator verifies this. Know what else is fairly close to that radius? The Mun! (1.2e7 m). Better yet, a retrograde ejection will bring you back towards that optimal altitude.

Doing this, your ejection burn only needs to add 580 m/s to Munar velocity. Under this plan, no leg (LKO -> Mun and Mun <-> Duna) needs more than 1300 km/s to complete. This allows greater mass fractions on a Duna transport. The Mun also allows for quicker rendevous because of the shorter orbit (vs the gate orbit)

The obvious weakness is the requirements of Mun based fueling and the relative simplicity of Duna transfers, but it does seem like an interesting concept.

Note: Duna (and possibly Eve) are the only compelling choices for a Munar way station. The higher your required infinite velocity, the smaller your gate orbit.

[cantab]

That can certainly work. Mun orbit makes a decent fuelling stop for interplanetary vessels in general for the reasons you mention, and its shorter orbital period compared to Minmus reduces problems with timing for transfer windows.

For further destinations than Eve and Duna you're better off departing Mun to get a low Kerbin Pe then burning there to eject. That will save about 600 m/s over a departure from LKO. It is also worth noting that even Mun>Jool direct actually requires a little less delta-V than LKO>Jool, it's just rather worse than Mun>LKO-Mun Transfer>Jool.

[maltesh]

For what it's worth, though, based on the edit dates of the Wikipedia "Gate Orbit" article, I strongly suspect that the guy who wrote the sole document linked in the references for the article also wrote the Wikipedia article. Not saying that the math is wrong, mind you.

[magnemoe]

This makes sense if you have good refueling operations on Mun.

Yes dropping from Minmus down to LKO make the burn trivial however its harder to plan and can easy require over an month planning time, not worth it for Duna, For Eeloo and Moho it does.

[FlyingPete]

If your mission includes a heavy fuel load due to a large delta-V budget, you also now have the advantage of being able to launch with the tanks nearly empty (just enough to get to the Mun) and refuel there using Munar ISRU. You can be constantly running mining excursions to keep the fuel station supplied.

[KerikBalm]

Basically, the same thing that was said here:

http://forum.kerbalspaceprogram.com/threads/136036-Oberth-effect

these orbits only make sense if you have a fuel depot there, and are less efficient than hohmans because you need to get to them first.

There is the limited case of which orbit you capture into at another planet, before departing again.

Also... that wikipedia article is terrible, and I'd recommend deleting it... or heavy revision.

A lot of stuff is poorly phrased, misleading, or wrong.

The English itself isn't great either.

Edited November 7, 2015 by KerikBalm