Just describe ghosts as some kind of sci-fi tech gone awry!
"We tried to beam back to our ship, but some freaky-deaky space storm did some shenanigans and now our molecules are floating around in a cloud. Help!"
A spectro-temporal entity, designated as 'Echo-1-alpha,' has been detected in the vicinity. This non-corporeal being is characterized by a persistent quantum flux anomaly, indicative of an unstable vortex in the space-time continuum.
Further analysis reveals a matrix of chrono-displaced energy patterns, which we're terming 'psi- waves.' These psi-waves are oscillating at a frequency of 3.14 terahertz, consistent with known manifestations of paranormal activity in subspace.