In fact, the "manned" aspect of space travel is the single biggest weakness of the whole process. Look at the space shuttle, for example. The elements of the shuttle that were needed to safely deliver humans into space and then bring them back safely made the whole thing so unwieldy and cumbersome that it ended up being a very expensive (and ultimately dangerous) boondoggle.
Trump tried to get this included in last year’s National Defense Authorization Act. It was opposed by virtually the entire DOD, including Mattis. The idea of a separate Space Corps was killed in conference. Instead, the 2018 NDAA boosts the position of Air Force Space Command, by extending the term of its commander to six years, and making it the sole command for all Air Force space forces.[24][25]
https://en.m.wikipedia.org/wiki/United_States_Space_Corps