can't see it, you infer it is there by the effect it has on surrounding objects...
wiki: dark matter refers to matter particles, not directly observed and of unknown composition, that do not emit or reflect enough electromagnetic radiation to be detected directly, but whose presence can be inferred from gravitational effects on visible matter. According to the Standard Model, dark matter accounts for the vast majority of mass in the observable universe.
supposively makes up 5/6ths of the mass of the known universe, yet we can't see or observe it directly....
so can we touch it? will it hinder possible space flight?
it keeps galaxies from spinning apart
is it....God??
g