I remember wondering way back when (60s or 70s?) why the heck did radio astronomy get so much funding - so much money was poured in. Only later was it revealed

I remember wondering way back when (60s or 70s?) why the heck did radio astronomy get so much funding - so much money was poured in. Only later was it revealed that once in a blue moon (heh), things were aligned so that the US could use bounces off the moon to detect and analyze a certain class of Soviet radars. Those periods of use for the radio telescopes in question were booked well in advance.