A post by Stewart Money about NASA undermining a technology that threatens the SLS: Detailed NASA Budget Bad News for Europa, Propellant Depot Advocates – Innerspace.net

Arguably, there is no greater enabling technology to be achieved with less overall investment than cryogenic propellant storage and transfer.  While we currently have the ability to conduct long term deep space missions using storable hypergolic propellants, their relatively low performance is a critical limiting factor in both robotic and crewed space missions.   Developing and demonstrating the ability store high performance cryogenic propellants in space for long periods of time without significant boil-off is nothing less than a necessity for long term exploration.  Taken together with the closely related challenge of transferring cryogenic propellants from one container to another in zero-g, as well as accurately measuring the amount of fluid in a storage vessel, the net result is leveraging effect with stunning capacity.  In fact, as the Augustine commission determined,

“In the absence of in-space refueling, the U.S. human spaceflight program will require a heavy-lift launcher of significantly greater than 25 mt capability to launch the EDS and its fuel. However the picture changes significantly if in-space refueling is used.” Furthermore “Studies commissioned by the Committee found that in-space refueling could increase by at least two to three times the injection capability from low-Earth orbit of a launcher system, and in some cases more. Thus, an in-space refueling capability would make larger super-heavy lift vehicles even more capable, and would enable smaller ones to inject from low-Earth orbit a mass comparable to what larger launchers can do without in space refueling.”

For a nation and an agency serious about exploring space, it is difficult to think of a single justifiable reason why proceeding with an orbital demonstration of this enabling technology should not be a priority. It is very easy to come up with an unjustifiable reason however.  It represents a viable alternative to SLS.

NASA, driven by Congress, studiously ignored Augustine’s findings when formulating plans for the Space Launch System, and as other websites have established, effectively buried internal studies showing that propellant deports offer a lower cost alternative on a much quicker time frame.   With a planned sub-scale flight demonstration now off the table, supporters of the “mega booster” will continue to be able to point to the absence of an actual demonstration of cryogenic transfer and storage as the circular justification for pressing on.

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