Anyone familiar with or can provide studies on Lunar SEP?Everything I've read focuses on either deep-space missions or LEO to EML/LLO, but I haven't seen anything on using SEP for only Lunar orbit maneuvers or just EML to LLO. In these instances, cargo would be launched to or through EML where SEP would direct it into its final Lunar orbit, then return for the next. This severally cuts down transit time, avoids Van Allens, reduces thrust requirements and I think is the best use for tugs. Thank You.
LEO to LLO is one of the standard examples where a SEP tug can be used.VASIMR is a suggested engine for the tug, so are Hall thrusters.This Wiki article can point you are some references.