I’d be fine cutting our manned space program entirely and spending the savings on propulsion research. I do think we need to reach for the stars, but it makes no sense to waste resources getting to places (like the Moon or Mars) just to get there. If we can’t take useful things (and people) there, or bring resources back – why go? We need propulsion advances so we can lift big things to space as well as build big things in space.
Ion Propulsion, described in this NASA article, is the sort of idea I’m talking about:
Using solar arrays spanning 65 feet, Dawn collects power from the sun to ionize atoms of xenon. These ions are expelled by a strong electric field out the back of the spacecraft, producing a gentle thrust. The weightless and frictionless conditions of space flight allow this gossamer force effect to build up, so the spacecraft gains speed slowly and continuously.
Most of our space program, IMHO, wastes money and resources (brain talent especially) in support of efforts that may be exciting to be part of but are of little long term use to the nation or humanity.