Why has this not been proposed, developed or patented before?
This solution requires ~50% more fuel than other concepts that use various forms of capture. Previously would have added $Ms to a mission, but with low cost SpaceX Rideshares to orbit, cubesats can carry significant fuel with no cost penalty. If water is used for fuel, then additional fuel is very inexpensive. We were also surprised that this had not been proposed before, but after some research it was felt it was truly unique. Being granted a US Patent proved it.