What we should do next 2.0 ?

(A)(1) Investigate with ground-based systems miscibility of noble ullage gases with cryogenic LH2, LO2, and LCH4

(A)(2) investigate mixing of noble gas ullage with Cryogenic propellants over hours, days and  weeks

(B)(1) investigate in space liquefaction/fractionation machinery in conjunction with a zero boil-off unit.

(B)(2) this machinery would be used to process gasses H2 and O2 out of noble ullage/ion propellant in hybrid chemical ion powered systems; investigate with ground-based experiments a Liquid air fractionation unit

(B)(3) removal of noble elements out of LH2 and LO2 in the case of a chemical refueling of a hybrid-powered stage

(C)(1) investigate with ground-based experiments with removing Noble gasses from Nitrogen oxygen gases in the case of the habitat’s being re-purposed as ion propellant tank. This is also done with an in-space liquid air liquefaction/fraternization system.

https://yellowdragonblog.com/2015/03/30/sls-skylab-iieus-deployed-pressurized-with-argonxenon-after-a-chemical-burn-sep-variant/ 

And;

https://yellowdragonblog.com/2015/04/11/liquefactionfractionation-unit-to-remove-gases-xenonargon-from-a-gases-hydrogen-or-methane-propellent/

(D)(1) We need to use a ground-based experiment to study of Noble gas ullage/Ion propellants with hypergolic propellants; If these behave better on longer-term missions and behave better on miscible issues then Hyperbolic chemical/ion powered hybrid stages then we could in future do trades with cryogenic ion powered hybrids

(E)(1) The ground-based Air liquefaction/fractionation unit leads the way to IRSU of rocks. Imagine the system at work on a landed hybrid propellent Xues/Centaur lander coupled to an Oxygen production system.

(F)(1) Air Liquefaction/Fractionation unit allows for the GH2/GO2/GCH4 in the propellant tanks to be separated from one another and fed to both The IVF and Ion propulsion systems since we envision that both systems are present and that both use the same propellant and oxidizer tanks.

EDIT 16 March 2016

(G) (1) Does Noble element ice sink or float in cryogenic oxidizers or propellant? I think if large Noble element ice forms it sinks