Not to be mistaken as being rude but a sincere question. Aren’t numerous comets contain ice?
I've heard this claim.
I wonder where they were supposed to have originated?
https://www.google.com/search?ei=8SBRXqDNCcS8sQXXs6SADQ&q=sublimation+of+ice+in+a+vacuum&oq=sublimation+of+ice+in+a+vacuum&gs_l=psy-ab.3..0i22i30l2.21299.25972..26404...0.2..1.712.7139.0j6j2j3j0j7j1......0....1..gws-wiz.......0i71j0i67j0i273j0j33i22i29i30.nJ4PktYbT9I&ved=0ahUKEwjgiZ_nluXnAhVEXqwKHdcZCdAQ4dUDCAo&uact=5