As seen in this
NASASpaceflight forum thread, the main benefits of staging a lunar mission at a halo orbit around the Earth-Moon L2 point instead of low lunar orbit are:
- line-of-sight communications from a landed spacecraft on the far side of the Moon, without the need for extra relay satellites
- "global access" to just about any landing site on the Moon (with minimal variance in the delta-v requirement), with a better "anytime return" capability because to do that with a low Lunar orbit rendezvous would require major orbital plane changes, which is why that mission profile is only limited to near-equatorial or polar landing sites.
The stationkeeping requirements are 400 ft/s (120 m/s) of delta-v per year. I haven't tried it yet, but maybe [ame="http://www.orbithangar.com/searchid.php?ID=4582"]this MFD[/ame] can be used to "teleport" the vessel (as described [ame="http://www.orbithangar.com/searchid.php?ID=4581"]here[/ame]) instead of having to switch to the vehicle all the time.
Getting to the lunar surface from the L2 point
requires 2520 m/s of delta-v compared to 1870 m/s for low Lunar orbit.
Also, a
lunar swing-by would be required to reduce the delta-v of arriving at the L2 point. Direct insertion would need 1230 m/s, while a lunar swingby would involve a 184 m/s maneuver at closest approach, and a 148 m/s maneuver at L2 arrival (total of 332 m/s). But does anyone know how to do that in Orbiter?