Frozen volatiles which include h2o ice are way more reflective to S-band radio waves than lunar rocks. Radio waves also have unique features when mirrored off ice than off silicate rock. An Assessment on the indicators returned from orbit 234 confirmed reflection features suggestive of h2o ice for your forever https://rafaelsjxgs.blogunteer.com/28170240/detailed-notes-on-ice-caps-moonrock